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I am trying to identify this plant

I am trying to identify this plant


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I am trying to identify this medium arching shrub growing to about 1.5m high x 2m wide in the subtropical climate of the Mt Coot-tha Botanic Gardens in Brisbane, Australia. Unfortunately there was no label with it. The inflorescence is about 3cm across, a greenish yellow, and made up of many tentacle-like florets. I don't think it is an Australian native plant.


It looks like combretaceae, or a species related to it.


Is anyone able to identify this organism? Sorry if this isn't the right place to post this, I will also be putting this in r/biology . I'm trying to identify this for a paper I'm writing on a local wetland here in Tampa, FL (Lettuce Lake Park)

You'll probably need flowers or botanical-fruits to know the species. Justicia americana (American Water Willow) grows in that kind of habitat but it could be an aquatic grass or perhaps a sedge. There is a subreddit r/whatsthisplant but theyɽ need more information too. Grasses & similar plants do flower. If you can not identify the species then you could maybe say there are aquatic grasses and sedges, & there are (or, you know, for a scientific paper they'll use some dry phrasing like "the presence of specimens of Poaceae and Cyperaceae was observed", but oy vey, let's get away from that kind of phrasing!)

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I used to monitor wetland plant communities in that area (including this location) for a former client.

The grass in the photo is not readily identifiable without reproductive structures (most grasses are not) but there are basically two real possibilities:

Maidencane (Panicum hemitomon) no long after wet-season emergence - if that is the case this grass will get much taller (2-3 feet more in this area, depending on how the water depth fluctuates between now and October).

Dicanthelium (Dicanthelium sp.) - within this genus, and in this area, species ID is almost impossible without reproductive structures. A member of this genus will not get much taller than what is shown in the photo.


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Abstract

In natural environments, plants are exposed to diverse microbiota that they interact with in complex ways. While plant–pathogen interactions have been intensely studied to understand defense mechanisms in plants, many microbes and microbial communities can have substantial beneficial effects on their plant host. Such beneficial effects include improved acquisition of nutrients, accelerated growth, resilience against pathogens, and improved resistance against abiotic stress conditions such as heat, drought, and salinity. However, the beneficial effects of bacterial strains or consortia on their host are often cultivar and species specific, posing an obstacle to their general application. Remarkably, many of the signals that trigger plant immune responses are molecularly highly similar and often identical in pathogenic and beneficial microbes. Thus, it is unclear what determines the outcome of a particular microbe–host interaction and which factors enable plants to distinguish beneficials from pathogens. To unravel the complex network of genetic, microbial, and metabolic interactions, including the signaling events mediating microbe–host interactions, comprehensive quantitative systems biology approaches will be needed.


Cindy Malone - genetic and epigenetic regulation of gene expression

Professor & Director CSUN-UCLA Bridges to Stem Cell Research Program
Ph.D. University of California, Los Angeles
email: [email protected]
Phone: 818-677-6145
Fax: 818-677-2034
Office: Chaparral Hall 5421
Malone website

My research program focuses on gene regulation or the process of how genes are turned on and off. Controlling when and where genes are turned on and off is critical for normal cell function. Without this strict control of gene expression, organisms would not develop properly or be able to sustain life. The study of gene regulation is a fundamental part of the search for more effective treatments for a wide range of diseases including heart disease, diabetes, autoimmune disorders, and cancer. Using standard molecular biology techniques, we dissect both the genetic factors and the epigenetic factors affecting the expression of several different gene promoters. Genetic factors involved in gene regulation include transcriptional activators and repressors whose interaction with gene promoters and enhancers are dictated by the DNA sequence, or changes in DNA sequence that occur through mutations. Epigenetic factors involved in gene regulation consist of chemical modifications to the DNA, like CpG methylation, and modifications to the chromatin, like histone acetylation, but do not involve DNA sequence changes.


Part 2: Nicotiana attenuata’s Responses to Attack from a Nicotine-tolerant Herbivore

00:00:13.05 My name is Ian Baldwin and I'm delighted, here, to be presenting Part 2 in a three-part
00:00:18.15 story on how to study the plant ecological interactions in the genomics era.
00:00:24.18 I'm a Director of the Max Planck Institute for Chemical Ecology.
00:00:28.16 And in Part 2, here, I'll be talking about Nicotiana attenuata, the plant that is right
00:00:35.12 here, it's ability to be able to respond to attack from a nicotine-tolerant herbivore.
00:00:42.12 And I just want to remind you this is Part 2 of a three-part series and in the third
00:00:48.04 part I'll be talking about the plant's perspective on sex, seeds, and microbes.
00:00:54.24 In Part 1, I talked about how the Max Planck Institute for Chemical Ecology came about
00:01:03.01 and how it fits into the rich history of the field of plant-herbivore interactions, and
00:01:06.24 how Ernst Stahl, in 1888, really started the field.
00:01:11.19 I also talked about the process of training genome enabled field biologists and how to.
00:01:18.05 how they are trying to phytomorphize themselves and understand what plants are doing with
00:01:23.00 this incredible chemical prowess that they have, and how they use those chemicals to
00:01:28.10 solve ecological problems.
00:01:30.09 I also introduced the "ask the ecosystem" approach, which combines both field and laboratory
00:01:36.02 studies of transgenic plants, and introduced the important process of silencing genes to
00:01:43.15 understand their function at a Darwinian level in an organismic context.
00:01:55.05 These field experiments are conducted with these genetically modified plants in their
00:01:59.16 native habitat in a nature preserve in the southwestern deserts of the United States,
00:02:05.14 in Utah, in a collaboration with Brigham Young University.
00:02:10.04 What I want to do here in Part 2 is talk about this particular interaction that's unfolding
00:02:15.24 to you right here.
00:02:17.22 This is an interaction of the plant that we work, Nicotiana attenuata, and the hawk moth,
00:02:25.24 Manduca sexta and Manduca quinquemaculata.
00:02:28.23 It's a remarkable interaction filmed here in fast motion, fortunately enough, by the
00:02:35.03 team of Volker Arzt from the movie Kluge Pflanzen, and they were so kind for letting us use their
00:02:40.09 outtakes.
00:02:41.09 This is a remarkable interaction because the plant is chock-a-block full of one of the
00:02:47.01 most toxic compounds for human beings, and for almost any animal with a neuromuscular
00:02:52.17 junction, namely, nicotine.
00:02:54.11 Now, many of us have had an addictive relationship with nicotine as smokers, but if any smoker
00:03:01.23 had ever tried to eat a Nicotiana plant you'd realize just how poisonous this plant is.
00:03:08.21 Nicotine poisons the neuromuscular junction, the acetylcholine receptor called the nicotinic
00:03:15.07 acetylcholine receptor, and that receptor mediates how muscles move.
00:03:21.03 Now, if you were a plant and you wanted to design a chemical defense which would poison
00:03:28.09 animals that moved with muscles, this would be an ideal defense compound to produce.
00:03:33.17 And this is exactly what Nicotiana attenuata and some of the other tobacco plants have
00:03:38.08 done -- they've evolved this molecule.
00:03:40.07 Now, this molecule evolved from two primary metabolic pathways, the NAD pathway and the
00:03:45.21 polyamine pathway, that produced the two rings that both contain a nitrogen and then they're
00:03:50.16 fused together to form the molecule. the molecule nicotine.
00:03:55.11 Nicotine is synthesized, as I said, from these two primary pathways, and its biosynthesis
00:04:00.02 has been worked out by a number of researchers over time.
00:04:03.07 But what is more recent is its understanding of the evolutionary history of this biosynthetic
00:04:08.08 pathway.
00:04:09.08 And this was done recently by Shuqing Xu in our department and a number of his colleagues
00:04:15.17 in the informatics group that is involved in assembling the genome of Nicotiana attenuata,
00:04:21.03 which is currently under review.
00:04:22.13 And what Shuqing Xu and colleagues found out was that umm. all of the genes that are
00:04:28.02 involved in nicotine biosynthesis are genes that are part of a whole genome triplication
00:04:35.13 event that happened with the Solanaceae, namely, all the plants that are of the group of plants
00:04:42.03 that are called solanaceous plants: potatoes, tomatoes, eggplant.
00:04:48.06 All went through a genome triplication event.
00:04:50.22 Those extra copies of the genes were therefore given the evolutionary privilege to be able
00:04:56.02 to be combined in novel things other than their primary metabolic pathways.
00:05:00.09 And potatoes and tomatoes and tobacco all produced nicotine, but tomatoes and potatoes
00:05:06.24 produce them at much lower levels -- about three orders of magnitude lower than tobacco
00:05:11.12 plants.
00:05:12.20 Tobacco plants' remarkable ability to produce enormous quantities of nicotine, to really
00:05:17.21 make it defensive, and smokeable, has to do with the ability of the plant to have corralled
00:05:25.11 the biosynthesis of those pathways into the roots, and to have fused the two rings in
00:05:30.16 a very efficient way, and funnel a lot of reduced nitrogen into the biosynthetic pathway.
00:05:36.08 That's described in this paper that is currently under review.
00:05:39.24 Now, nicotine biosynthesis can be inhibited by silencing a single gene.
00:05:45.14 This gene, here, putrescine methyltransferase, which we have silenced by RNAi and been able
00:05:51.13 to produce plants that are relatively nicotine-free.
00:05:55.01 And when you make a plant that's relatively nicotine-free and you take it back out into
00:05:59.06 the native habitat and plant it in some natural habitats, you realize just how effective this
00:06:04.00 defense is.
00:06:05.00 Because every deer, every rabbit, every gopher in the neighborhood finds out about it, and
00:06:11.11 here's an example of a gopher that's coming up, has dug a special tunnel up underneath
00:06:16.13 this nicotine-free plant and is pulling it down to its burrows.
00:06:20.00 So, without nicotine, the plants become quite defenseless and are stripped bare of their.
00:06:27.13 of their phloem by rabbits and other mammal. mammalian browsers them, and usually don't
00:06:32.17 last very long.
00:06:34.16 Now, Manduca sexta, which was gobbling, devouring those plants in that first video that I showed
00:06:39.21 you, is able to do it because it is. well, it basically holds the world's record for
00:06:45.14 nicotine tolerance.
00:06:47.00 If you compare the LD50 -- the lethal dose at which 50% of an experimental population
00:06:52.15 dies -- you realize that even the most hardcore, [unknown], carton-a-day smoking human being
00:07:00.23 still has an LD50 that is 750 times lower than that of Manduca sexta, which is about
00:07:08.18 1500 milligrams per kilogram that it's able to tolerate.
00:07:12.11 Now, it's been known since the '60s that Manduca sexta's tolerance of nicotine is based on
00:07:19.11 a physiology that allows it to excrete all the nicotine that it ingests without any apparent
00:07:26.04 metabolism at. or any apparent effect on its nervous system.
00:07:30.22 How it does that is still very much an active area of discovery, but, as we look at a caterpillar
00:07:38.05 eating a plant, we've been interested in asking the caterpillar, transcriptomically, what
00:07:44.10 is it doing inside of its gut to be able to handle those many human doses of lethal doses
00:07:50.22 of nicotine that it's ingesting almost on an hourly basis.
00:07:55.00 And when you ask the caterpillar, transcriptomically, there is consistently one cytochrome P450
00:08:02.09 which is constantly being regulated in direct proportion to the amount of nicotine that
00:08:06.00 is ingested by the caterpillar.
00:08:07.07 And this is a cytochrome P450 with a long complicated name called 6B46.
00:08:14.11 And you can see it regulates at a high level when it's eating nicotine-containing plant
00:08:18.15 and downregulates when it's eating nicotine-free plants.
00:08:22.02 So, to understand what this particular gene was doing in the caterpillar and why it was
00:08:28.04 being up-regulated every time the caterpillar ate a high-nicotine-containing plant, two
00:08:33.13 scientists in the department, Pavan Kuma and Sagar Pandi, designed a procedure that allowed
00:08:44.06 the study of this particular gene to occur in the natural environment of both the insect
00:08:48.21 and the plant.
00:08:50.03 And what they did was they took that gene, made a double-stranded contract, which is
00:08:53.14 depicted here in yellow in the plant, transferred it into the plant so that was consistently
00:08:58.10 expressing this double-stranded piece of the gene that they wanted to silence, and then
00:09:03.23 they planted it out in Utah and let free-ranging caterpillars feed on them.
00:09:09.16 And, in that process of feeding on these particular plants, the caterpillar ingests double-stranded
00:09:15.04 and then the gene in the caterpillar gets silenced.
00:09:18.19 And in those genes silence caterpillars they were able to understand the function of that
00:09:24.22 particular cytochrome P450, which is up-regulated during the defense process.
00:09:31.08 And what they discovered was really remarkable, but let me show. first show you some data
00:09:35.04 on just how effective this plant-mediated RNAi process is.
00:09:40.08 Here on the y axis is the transcript levels for the particular gene that they're looking
00:09:44.21 at in the various tissues of the caterpillar.
00:09:47.15 And I want you to focus particularly on the midgut, which shows that caterpillars eating
00:09:54.18 nicotine-containing plants have very high levels of that transcript.
00:09:58.14 But if the caterpillars are feeding on a nicotine-free plant, the transcript levels are quite low.
00:10:04.07 But if the caterpillars are feeding on one of these PMRi.
00:10:08.03 PMRi plants that are expressing a double-stranded construct of that cytochrome P450, and those
00:10:14.15 plants contain normal high levels of nicotine, you would expect the transcript levels to
00:10:19.16 be this high, but instead they're that low.
00:10:22.21 And they're that low because the gene is being silenced by that plant. by the plant's food,
00:10:31.01 and the caterpillars are ingesting that gene and that RNAi process is happening in basically
00:10:36.19 free-living, free-ranging caterpillars in the field.
00:10:39.15 It's a remarkable experimental tool that allows us to study plant-insect interactions in nature
00:10:45.04 using genetic tools to manipulate not just the plant, but also the insects that are feeding
00:10:50.01 on the plant.
00:10:51.04 Now, what's remarkable about this story is that it was actually a wolf spider occurring
00:10:56.04 in the natural habitat of the plant that told us the function of this particular gene in
00:11:03.12 the caterpillar.
00:11:05.09 And now I'm going to show you a series of videos and here's a video of a wolf spider
00:11:09.14 attacking a nicotine-free plant and you can see from that video that it just gobbled it
00:11:14.21 up.
00:11:15.21 So, if the caterpillar is feeding on a nicotine-free plant it has no nicotine in it and the wolf
00:11:21.05 spider finds it as food.
00:11:23.21 Now, here is, in the next video, a spider attacking a caterpillar that is fed on one
00:11:30.01 of these PMRi plants.
00:11:31.14 Now, remember those have are full of nicotine but they are silencing this particular gene
00:11:36.17 in the caterpillar.
00:11:37.18 And you can see from this video that the caterpillar is attacked and eaten as if it was nicotine-free,
00:11:44.06 and this was discovered by the two scientists who had placed caterpillars on plants out
00:11:51.04 in the field, having them feeding on these particular plants that silence the gene in
00:11:55.05 the caterpillar, and all the caterpillars disappeared at night.
00:11:58.12 And the wolf spider hunts at nighttime and that's how they found the wolf spider.
00:12:02.18 Now, here is the key moment, the key observation that allowed them to understand what was going
00:12:08.09 on, because in the next video here is a spider attacking a nicotine-containing plant, that's
00:12:17.01 a normal empty vector wild-type plant, and you can see all it did was go up and palpitate
00:12:22.21 the spider. the caterpillar and then it immediately backed away.
00:12:26.06 And what was going on in that palpitation, that little moment when the caterpillar being
00:12:31.07 assessed by the spider and the spider decided, oh.
00:12:33.15 I'm not gonna eat this, was that the caterpillar was, through its spiracles. caterpillars
00:12:40.16 have 17 spiracles, they are basically the lungs of the caterpillar. caterpillars have
00:12:46.06 all these tubes and that's how they exchange air. and through the spiracle the caterpillar
00:12:51.01 is puffing out a load of nicotine into the face of the caterpillar. into the face of
00:12:57.06 the attacking spider.
00:12:58.06 And that's why the attacking spider jumped away.
00:13:01.11 And what this gene is doing is mediating that process, in a way that we don't really understand
00:13:06.08 biochemically, allowing the caterpillar to basically divert a lot of. some portion
00:13:11.13 of that massive amount of nicotine that's flowing through its gut, that it's excreting
00:13:15.02 out, but then it moves it into the spiracles and it uses it defensively when a spider comes
00:13:20.03 up and says, are you good food?, and the caterpillar then just puffs out this thing of nicotine
00:13:23.23 and repels it, okay?
00:13:26.10 So, that shows you that, actually, the caterpillar, even though it's excreting most of its nicotine,
00:13:32.16 is using it defensively, it's co-opting just a small fraction of what's going through its
00:13:36.19 gut for its own defensive purposes.
00:13:38.09 But, now, what I'm going to tell you, for the rest of this talk, is what happens when
00:13:43.20 the plant recognizes that it's being attacked by that particular nicotine-tolerant caterpillar.
00:13:50.21 Because that recognition process results in six changes in the plant that all involve
00:13:58.07 how the plant deals with a caterpillar that has broken through one of its major defenses
00:14:04.00 and has to figure out something else to do with this guy that's going to eat it, and
00:14:08.18 that's going to make lunch of it.
00:14:10.08 And that recognition process starts right here.
00:14:13.15 And if you look right at that cut leaf edge, there, you can see a little bit of green slimy
00:14:18.10 stuff that the caterpillar is leaving on the edge of the leaf.
00:14:21.19 Now, it turns out it's not doing that intentionally, that's just part of the eating process, it's
00:14:25.13 part of its oral secretions, that's part of the process of masticating the leaves to be
00:14:29.06 able to digest it, but in those oral secretions are a group of compounds that are called fatty
00:14:35.07 acid amino acid conjugates.
00:14:36.24 FACs is what we call them, and the structures of those FACs are right here.
00:14:41.11 They're very simple molecules -- they're just fatty acids esterified to amino acids.
00:14:45.16 There's two of them, there's five fatty acids, and they make basically eight different structures,
00:14:50.04 and those eight structures are what the plant uses to say, aha I'm being attacked by Manduca
00:14:57.24 sexta and I know that it's nicotine resistant in some way or another.
00:15:00.23 And those are.
00:15:01.23 I'm anthropomorphizing but that's basically the message.
00:15:04.20 Now, what I'm going to do. this is, by the way. this fatty acid amino acid conjugates
00:15:09.06 were discovered by Rayko Halitschke in his thesis and published back in 2001.
00:15:13.14 What I'm going to do now is to take you through those six layers of defense, avoidance, and
00:15:19.24 tolerance that the plant goes through when it recognizes this. that it's being attacked
00:15:27.01 by this. this particular caterpillar.
00:15:31.00 And those six layers are both an up and down regulation of direct defenses, a bunch of
00:15:35.23 indirect defenses, an interaction between indirect and direct defenses, tolerance responses,
00:15:41.07 and avoidance responses.
00:15:43.02 So, follow with me and we're going to go through this remarkable journal. journey of what
00:15:47.23 happens to the plant as it reorganizes its metabolism, physiology, to deal with the fact
00:15:54.19 that it's got a predator that it really has to deal with.
00:15:58.11 Okay.
00:15:59.11 Now, first I want to talk a little bit about the recognition process.
00:16:02.15 So, umm. we've been able to, because we have these synthetic fatty acid amino acid
00:16:08.23 conjugates, we have the elicitors. we're able to start the interaction between plant
00:16:14.05 and its responses without having to have a caterpillar.
00:16:17.06 So, we simply just take a pattern wheel and we add these oral secretions to spit to the
00:16:21.10 leaves, to the holes that are made in leaves with the pattern wheel, and that elicits a
00:16:25.05 very complicated set of signaling responses.
00:16:28.14 We haven't identified the elicitor. the. the receptor yet for the elicitor.
00:16:32.03 We know the elicitor -- those are the FACs, the receptor is unknown, but that that elicits
00:16:38.12 a very complicated signaling network that involves MAP kinases, SIP and WIP kinases,
00:16:43.19 the jasmonate signaling cascade, and a lot of modulation of that jasmonate signaling
00:16:50.11 cascade through other kinases, the activation of CDP kinases as well, and the perception
00:16:59.04 by other receptors, LecRK, that it basically involves a regulation of jasmonate signaling.
00:17:06.05 And, because caterpillars do not brush their mandibles when they eat a plant, they also
00:17:11.14 contain bacteria and other sorts of bacterial signals, and the plant has to make sure that
00:17:16.18 it's activating a jasmonate signaling cascade and not a salicylate signaling cascade, so
00:17:22.17 all of this signaling has to do with being able to make sure that the caterpillar doesn't
00:17:28.09 fake out the plant with its bacterial signals, but rather generates a nice clean jasmonate
00:17:35.07 response, which activates five out of the six layers that I'm now going to talk to you
00:17:39.10 about.
00:17:41.03 Now, that was a lot of work, and that work was done by some remarkable group leaders
00:17:48.00 and a remarkable number of talented students that I wish I could talk about in greater
00:17:52.16 detail -- but here are their pictures.
00:17:55.13 It also illustrates another important message that I want to bring up in this talk and that
00:17:59.17 is that interplay between mechanism and function, that if you understand the details by which
00:18:06.00 these responses come about, you have the very tools that you can manipulate genetically
00:18:11.13 to be able to create plants that are not able to show the response, and all of those steps
00:18:17.00 in those signaling pathways have been very useful tools to allow us to be able to manipulate
00:18:22.23 some aspects of these six responses in different combinations, and test them functionally in
00:18:27.15 the field, in the actual habitat in which the plant evolved.
00:18:31.23 Now, let me go through the six responses.
00:18:34.00 The first response was the up- and down-regulation of these, what we call, direct defenses.
00:18:39.07 Now, direct defenses basically can be categorized in two groups.
00:18:43.05 They're either toxins, things that poison animals that eat plants, without poisoning
00:18:49.10 the plant too much, and are specifically targeted against the things that are different between
00:18:54.15 animals and plants, like nervous systems plants don't have a nervous system, so it's
00:18:58.19 really easy for plants to make nervous system poisons that are not toxic to them, but are
00:19:04.18 very toxic to the animals that want to eat them.
00:19:07.01 So, in addition to toxins, there's also another type of direct defense that are called digestibility
00:19:12.08 reducers.
00:19:13.08 They're basically interfering with the main reason why a caterpillar wants to eat a plant
00:19:18.11 in the first place, which is to turn caterpillar protein. plant protein into caterpillar
00:19:23.23 protein, to turn caterpillar. plant energy substances like glucose and sucrose and starch
00:19:30.02 into energy substances that the caterpillar can use.
00:19:33.11 So, that digestibility process can be interfered with lots of different ways.
00:19:40.00 Interfering with all the steps of ingestion and digestion. for example, there are protease
00:19:45.06 inhibitors we're going to talk a little bit about, there are tannins and amylase inhibitors
00:19:48.11 that are basically affecting the digestive enzymes that take apart plant proteins and
00:19:52.21 starches, and make them available to be uptake. taken up by the guts of caterpillars.
00:19:57.24 But there's also abrasives, things that wear down the mandibles and the teeth of the herbivores,
00:20:02.20 because, you know, if an herbivore doesn't have a pair of teeth, a set of mandibles or
00:20:08.18 a set of teeth, it can't chew a plant.
00:20:10.24 And plants fill themselves with silica and other sorts abrasives that just wear down
00:20:15.18 the teeth.
00:20:16.18 And there is no easier way to starve an ungulate than to wear out its teeth, and plants do
00:20:22.17 that all the time.
00:20:23.17 Now, I just want to talk about the down-regulation, as well as the up-regulation, because the
00:20:28.09 first thing that happens when those FACs are recognized by the plant is the plant has an
00:20:34.02 ethylene burst and shuts down the very gene that we silenced to make a nicotine-free plant.
00:20:38.24 And that's in fact the reason why we did it, because we learned from the caterpillar how
00:20:43.17 it was shutting down nicotine biosynthesis in the plant.
00:20:48.02 And it's very clear, now, that since the caterpillar is co-opting a certain portion of the nicotine
00:20:53.13 for its own defense, the plant is most likely down regulating its nicotine production so
00:20:59.00 that the plant. so the caterpillar can't co-opt the extra nicotine it produces.
00:21:02.23 If it was a deer or a rabbit producing. doing the damage rather than a Manduca sexta
00:21:08.14 larvae, nicotine production would be operated 5- or 6-fold and the. you know, the plant
00:21:14.17 would become even more full of nicotine than it already is, so that a single leaf would
00:21:20.00 have the same amount of nicotine in it as half a carton of [unknown] cigarettes.
00:21:24.13 So, that massive up-regulation process is just basically stopped and the. the plant
00:21:30.01 is down-regulating nicotine production when it knows that it's being attacked by a nicotine-resistant
00:21:34.10 caterpillar.
00:21:35.10 Okay.
00:21:36.10 Then it produces a whole bunch of other types of compounds, many of which we had no idea
00:21:41.06 what they did.
00:21:42.06 And I just want to talk, just briefly, about a group of compounds called diterpene glycosides.
00:21:47.03 This is some work done by a PhD student who's just finishing enough, Sven Heiling, and he's
00:21:51.06 done some beautiful analytical work characterizing these molecules that were basically unknown.
00:21:56.15 There were 46 of them in Nicotiana attenuata and they are basically produced in the chloroplast
00:22:05.23 by what's called the MEP pathway and the DOX pathway, to produce a basic backbone diterpene
00:22:13.02 structure, and that backbone diterpene structure is depicted there.
00:22:17.10 It's hydroxylated and then sent out to the plant and decorated further by enzymes that
00:22:24.11 add different types of sugars to them -- I'll talk about that a little bit later.
00:22:29.12 But, because this is a secondary metabolic pathway, the main enzyme that's involved there,
00:22:35.22 this NaGGPPS that is highlighted in bold, there, also has three copies, because of that
00:22:43.12 trip. the genome duplication event, and, if you silence the one that's dedicated for
00:22:48.04 the production of these pathways, you can completely take out the whole biosynthetic
00:22:52.03 pathway by one gene silencing step.
00:22:54.20 So, by silencing that particular gene, we're able to make DTG-free plants and if you fed
00:23:01.07 them to caterpillars you can see that the caterpillars basically were able to increase
00:23:06.19 their growth rate almost fivefold when they're feeding on these DTG-free plants.
00:23:11.19 So, even though we had no idea that these were toxic or defensive when we looked at
00:23:17.07 the structures and figured out their structures, when we silence them and produce plants that
00:23:21.05 were where DTG-free the caterpillars told us that, oh. this is really a pretty nasty
00:23:26.17 defense compound.
00:23:28.18 And what Sven has been able to do is to identify all the different enzymes that are involved
00:23:33.22 in decorating them with sugars of various sorts, glucose and rhamnose, here, and then
00:23:40.18 they are malonated in addition, and that's what generates all those 48 different.
00:23:43.19 48 different structures.
00:23:44.20 Now, it turns out that if you look at the. the poop of a caterpillar, the frass that
00:23:50.04 comes out the busi. the other end of the caterpillar after it's eating leaves, Spoorthi
00:23:54.15 Poreddy, who is a PhD student who just finished up, along with Sven and Jianciai Li, have
00:23:59.21 been discovering that there's a very interesting dynamic that's going on in the caterpillar's
00:24:06.13 gut as it's trying to remove particular sugar groups from these DTGs, in a way so as not
00:24:13.07 to expose the toxic backbone, which is toxic to the plant also, but also not remove all
00:24:18.00 of them, which produces other toxic compounds.
00:24:21.07 So, this is a story that is ongoing, we're going. we're still working on it, but there's
00:24:25.22 this wonderful digestive duet that's occurring as the caterpillar is removing certain sugar
00:24:31.03 molecules and putting them back on, and putting other molecules back on to protect it and
00:24:36.02 detoxify this molecule as it goes through -- an example of direct defenses.
00:24:41.03 Now, I want to switch to indirect defenses.
00:24:45.05 Now, indirect defenses are based on a concept that probably every politician knows.
00:24:51.06 Now, here's the basic scenario.
00:24:53.22 Here's the plant.
00:24:54.22 And the plan is attacked by Manduca sexta, which is its enemy, right?
00:24:59.02 Now, Manduca sexta is, in turn, attacked by other predators that are all depicted here,
00:25:04.22 there are six of them right here, and they of course are the predators of the herbivore.
00:25:11.11 Now, anyone knows that the enemy of your enemy is your friend.
00:25:17.02 And that is the basis of how indirect defenses work.
00:25:22.09 Indirect defenses, in contrast to the direct defenses, are signals or traits that the plant
00:25:29.24 produces that help predators or parasitoids find and feed on the herbivores that are feeding
00:25:37.02 on them.
00:25:38.23 And that's what that indirect defense looks. how that works.
00:25:41.23 Now, the way it works in Nicotiana attenuata is that, when Manduca sexta begins to feed
00:25:47.06 on an attenuata plant, the plant recognizes it from those FACs that are in the caterpillar's
00:25:52.07 spit and it activates a series of transcription factors, and it activates the production of
00:25:57.05 a beautiful, volatile bouquet, like a Chanel No. 5 that's released not just from the attack
00:26:02.14 leaf but the entire plant.
00:26:04.15 And it's basically just producing this signal that includes a number of molecules, the most
00:26:10.00 important of which is a sesquiterpene called trans-alpha-bergamotene, and trans-alpha-bergamotene
00:26:15.22 attracts this little predator that's down here called Geocoris pallens, a little predator
00:26:20.13 that lives around in the soil on the plant, and it's basically listening, smelling in
00:26:25.06 the air, and when it senses that molecule it knows there's a caterpillar feeding on
00:26:29.17 a plant somewhere.
00:26:30.23 But that little Geocoris also needs local information.
00:26:34.18 Once it arrives on a plant, the plant is big, the caterpillar could be anywhere in the plant,
00:26:39.07 and it utilizes other compounds like these green leafy volatiles on the top there, and
00:26:43.12 particular. particularly the change in a double bond in those green leafy volatiles
00:26:47.23 that gives it local information and allows the Geocoris to be able to localize where
00:26:52.22 on the plant that particular caterpillar is feeding.
00:26:55.07 And, when it gets there to the caterpillar, it just plunges its beak inside the caterpillar
00:27:00.17 and sucks it out and it does that many times.
00:27:04.03 And so what this process is just like calling the police.
00:27:08.12 It doesn't have to do anything more than simply provide accurate, honest information about
00:27:14.20 where a caterpillar is feeding on it, how it's being attacked, and then the predators
00:27:19.05 take it from there.
00:27:21.10 It's a wonderful evolutionarily stable way of dealing with defense because the evolutionary.
00:27:26.19 coevolutionary loop between plant and herbivore is broken by this predator link.
00:27:33.04 Now, we discovered that thanks to the brilliance, really, of the graduate student in the group,
00:27:38.23 Andre Kessler, who is now professor at Cornell, and he invented a predation assay that allowed
00:27:44.04 us to monitor the behavior of this predator in the field under natural conditions.
00:27:48.13 And the predation assay was beautifully simple.
00:27:51.00 He simply just glued eggs of this Manduca onto the bottom of leaves and used those eggs
00:27:59.03 as a monitor for whether or not the predator had come up to the plant.
00:28:02.24 The predator is a very skittish predator.
00:28:05.16 It's called the big eyed bug. it has big eyes, it pays attention to a lot of things,
00:28:10.03 you can't walk up and see, it runs away. and so you need an indirect way to know whether
00:28:14.06 or not it's been around.
00:28:15.21 And yet, when the predator feeds, you can see that it sucks out the egg and it leaves
00:28:19.23 the egg in a nice state behind, and by gluing eggs onto the plant you can see how many predators
00:28:27.06 have come up and visited the plant.
00:28:29.01 And that predation assay had allowed us to be able to work out the transcription factors
00:28:32.17 that regulate volatile production, which volatiles are important, the long- and short-distance
00:28:36.12 signals, all the details of this particular process.
00:28:39.14 Now, it turns out that these indirect defenses don't work alone they work in synergy with
00:28:46.09 the direct defenses.
00:28:48.04 So, when the cater. when the caterpillar attacks a plant and it causes the plant to
00:28:52.16 produce this wonderful volatile bouquet that is functioning as an alarm call, bringing
00:28:57.24 in predators from long distances away, that will then attack the caterpillars, there are
00:29:03.05 other things going on too, namely that the plant is also producing compounds that are
00:29:08.24 interfering with the digestive process.
00:29:11.06 And these are the protease inhibitors that Jorge Zavala worked on, and the protease inhibitors.
00:29:16.00 here's a seven-domain protease inhibitor. and what they do is they inter. interact
00:29:20.16 with the digestive enzymes of the caterpillar's gut and keeps the caterpillar from digesting,
00:29:25.06 which means that the caterpillar can eat and eat and eat but it doesn't grow, because it's
00:29:28.15 not getting the nutrients.
00:29:30.03 Now, when a caterpillar goes through the stages from being small to large, it becomes pretty
00:29:36.01 immune to this predator, because it's a bratwurst-sized caterpillar at the end and it pretty much
00:29:41.00 can thumb its nose at this little predator who is trying to attack it.
00:29:44.21 But if the plant keeps the caterpillar in a nice, small, vulnerable stage longer, the
00:29:49.20 indirect defense of the predator works much better.
00:29:52.14 So, it's the synergy between direct and indirect defenses that really helps to bruise the.
00:29:58.02 lower the population of caterpillars.
00:30:01.05 Now, there's another type of synergy that occurs as well, and this is depicted very
00:30:05.08 nicely in some videos by Mary Schuman, who is pretending to be a Geocoris predator, sticking
00:30:10.22 a little blue pin up the butt of the caterpillar.
00:30:13.02 And you can see, on a caterpillar that's feeding on a wild-type plant, a wild-type plant that's
00:30:17.11 full of defenses, it's behaving pretty sluggishly -- it's not moving at all when she's poking
00:30:23.17 it, she picks it up with the forceps, it doesn't do any wagging, it just hangs there limp like
00:30:28.01 a doornail.
00:30:29.02 Now, remember this caterpillar is spending a lot of metabolic energy detoxifying the
00:30:34.13 defenses that are in the leaves, the direct defenses.
00:30:39.01 And it doesn't have a whole lot of energy to fight back when it's attacked by predators.
00:30:45.00 Compare that when Mary tries to poke a caterpillar that's feeding on a protease-inhibitor-free
00:30:50.21 plant -- it's got plenty of energy.
00:30:52.11 It's banging around, it's thrashing, and it's defending itself quite well.
00:30:56.24 And that's another example of the synergy between direct and indirect defenses, is that
00:31:04.00 caterpillars that are feeding on toxic plants are lethargic.
00:31:06.15 They are having to spend a lot of energy detoxifying all those metabolites that are going through
00:31:11.22 them, and that slows them down and makes them much more vulnerable to their predators.
00:31:18.00 We so frequently forget because we eat defenseless plants in our normal food supply, we made
00:31:24.09 them defenseless through our agricultural practices, that we forget that eating native
00:31:28.11 plants that are full of chemicals is actually hard, metabolically demanding work.
00:31:34.24 Now, there's another type of direct defense. indirect defense that I want to tell you about.
00:31:39.08 And that's an indirect defense that occurs in the trichomes, which are these little hairs
00:31:43.03 on the surface of the leaves, and you can see as a little droplet appearing here from
00:31:47.11 this magnification of a trichome on the surface of an attenuata leaf.
00:31:50.22 Now, in the trichome is. is a particular type of compound called an acylsugar.
00:31:55.18 Now, acylsugars were thought to be direct defenses, toxins, and there's a good bit of
00:32:01.00 evidence that they are sticky substances that catch insects and sort of tie them up.
00:32:06.13 But. and this was actually first worked on by Alexander Weinhold in the group, and
00:32:11.23 Alexander characterized the structures of these things, and that these acylsugars basically
00:32:17.02 consists of a sucrose molecule and then on each of the hydroxyl groups of the sucrose
00:32:21.10 molecule is esterified a small, short-chain fatty acid.
00:32:26.03 Here are the characteristics of these short. short-chain fatty acids, and these short-chain
00:32:31.06 fatty acids have the smell of baby barf. they're sort of an unpleasant smell and that's the
00:32:36.15 reason why Alexander actually started the project in the beginning, because he had to
00:32:40.08 take care of the caterpillar colony, and he always thought that the caterpillars smelled
00:32:44.15 fairly bad, and. and noticed that when they were feeding on these leaves they were of
00:32:51.03 course eating acylsugars.
00:32:53.02 And when we took these plants to the field. took plants to the field and noticed what
00:32:57.03 caterpillars did when they first hatch out of their egg, we noticed that these. these
00:33:01.05 acylsugars are not defensive at all, they're in fact the first meal of a caterpillar.
00:33:05.11 A caterpillar hatches out of its egg and it begins to lick these. these tops like they're
00:33:10.07 little lollipops, and they get their first meal, and, in the process of getting that
00:33:15.00 first meal, they end up getting a body odor.
00:33:19.00 And the body odor comes from eating those acylsugars and having those fatty acid groups
00:33:24.16 deesterify and come off the body.
00:33:27.09 And so the caterpillar begins to smell of those baby barf fatty acids that are esterified
00:33:33.12 to those sugars.
00:33:34.13 Now, we were very interested to know whether or not smelling attracted the attention of
00:33:39.11 predators that were on the plants.
00:33:41.04 And so we looked at all the predators that occur on plants and none of them cared about
00:33:45.03 this. these baby barf smells -- they didn't seem to respond more to caterpillars that
00:33:48.23 were scented or non-scented.
00:33:50.02 So, we investigated some more.
00:33:52.08 But it turns out that there was another thing that these compounds did to a caterpillar's
00:33:58.21 body odor.
00:33:59.24 Not only did it change the body odor, but it also changed the smell of its poop.
00:34:04.24 There was a caterpillar just pooping there.
00:34:07.03 And poop, when it happens, when it falls, usually falls according to the laws of gravity.
00:34:16.03 It falls down.
00:34:17.03 It doesn't always hit the fan as. as the metaphor goes.
00:34:20.20 And the caterpillar, when it poops, produces a smelly, fresh, redolent poop that falls
00:34:27.14 directly on the ground, and this is Utah where the ground is hot, it's frequently 50 degrees,
00:34:32.16 and those are short-chain fatty acids, so they immediately volatilize, and after five
00:34:36.20 minutes or so they become scent-less and they no longer have that smell.
00:34:41.01 But for five minutes, when the fresh poop has fallen on the ground, it's providing beautiful
00:34:46.01 information to a whole other group of predators.
00:34:49.23 And those are the predators that are walking along in the ground, the lizards and the ants,
00:34:54.19 and it turns out that the lizards and the ants use that volatile information to know
00:34:59.07 that, oops, there's a caterpillar above them, they can just climb up the plant.
00:35:03.03 And you can take fresh frass and dried frass, or you can just isolate the. that. that.
00:35:09.07 those fatty acids and make your own little perfume, which will be available in duty-free
00:35:13.19 shops soon, and call it the scent of the caterpillar, and you can spray it on the ground and spray
00:35:17.16 it on sticks in front of ant nests, and the ants will just come charging up after you've
00:35:21.23 sprayed them, looking for caterpillars.
00:35:24.06 And so, in the end, these trichomes may well be the first meal for the caterpillar, and
00:35:32.05 they're delicious, sugary lollipops, but in the process of scenting their bodies and scenting
00:35:38.10 their frass, they actually turn out to be evil lollipops because they tag them for predation.
00:35:43.16 And that's just another example of how a plant is utilizing indirect defenses to protect
00:35:49.22 themselves.
00:35:51.00 They have very clever ways of bringing in predators.
00:35:54.07 And that was the fourth layer.
00:35:55.23 Now, I'm going to go to the fifth layer, now, and the fifth layer activated by those fatty
00:36:02.06 acid amino acid conjugates that are in the caterpillar's spit.
00:36:05.07 In the fifth layer is a layer of tolerance responses that the plant activates.
00:36:10.15 We had talked earlier in Part 1 about how a plant is a growth machine, fixing carbon
00:36:15.23 dioxide, taking that carbon dioxide, making a whole bunch of metabolites for growth, reproduction,
00:36:21.03 storage, and defense, but at the same time it's also possible to use it to make the plant
00:36:28.10 more tolerant of herbivore attack.
00:36:31.07 Now, until this work, the whole tolerance thing was pretty much a trait-less concept,
00:36:36.01 something that you could look at in populations of plants, but not something you could really
00:36:40.02 nail down to a particular trait.
00:36:42.05 And here we've been able to nail it down to a particular trait.
00:36:45.06 And it came, again, from a field observation.
00:36:47.09 The field observation was that caterpillar-attacked plants, after they plants had senesced and
00:36:53.04 dried out, and then there was another rain, they frequently reflowered -- they produced
00:36:58.00 new flowers after a rain -- but the plants that were not attacked by caterpillars didn't
00:37:02.15 do this reflowering.
00:37:03.16 So, that was an interesting observation.
00:37:05.12 And you sort of wondered, where did these caterpillar-attacked plants get the resources
00:37:09.14 to reflower?
00:37:10.20 This is an annual plant it should have shut down life, made all the flowers that it could've,
00:37:14.22 and senesced and called it quits.
00:37:16.07 But that's not what they were doing.
00:37:17.21 And I think the answer comes in the life history of the caterpillars that feed on them.
00:37:23.20 Caterpillars go through two stages.
00:37:25.08 They have the eating machine stage, which is depicted right here, where Manduca.
00:37:29.24 Manduca sexta is simply just a larvae trying to consume as much plant material as possible,
00:37:33.18 but then it pupates and molts into this beautiful moth, and it becomes a sex machine.
00:37:39.21 And, as a sex machine, it's no longer eating the caterpillar. eating the plant anymore.
00:37:44.09 And that means that the caterpillar is out of its. out of the concerns of the plant,
00:37:49.13 and the plant, if it had waited and stored resources somewhere else, it was able to reflower
00:37:55.05 and start that whole process over again without having the tissues being lost.
00:37:58.24 And this is what is happening.
00:38:00.19 When. and this is work done by Jens Schwachtje, and his PhD project, and he discovered that
00:38:06.24 the FACs in caterpillar's spit, they elicit a bunkering of photoassimilates into the roots.
00:38:13.20 Now, a plant is a growth machine, right?
00:38:15.22 It's assimilating carbon dioxide from the air and, normally, it would be fixing those.
00:38:20.24 that carbon dioxide into sucrose and sending it from source leaves up to sink leaves to
00:38:25.17 grow more leaf area to make more of a growth machine -- that's what plants normally do.
00:38:30.00 But if they're making more of a growth machine, they're also making more leaves for the caterpillar
00:38:34.03 to eat, grrr.
00:38:35.03 So, you need to stop that process.
00:38:37.12 And when you have a caterpillar on the plant, or you put FACs on a plant, and it doesn't
00:38:42.18 matter where on the plant, the plant, instead of taking that fixed CO2 and sending it up
00:38:48.07 to young sink leaves, it bunkers it down below ground.
00:38:51.15 And it. and Jens was able to show this with some beautiful experiments in collaboration
00:38:56.04 with the Phytosphere Julich, which has a synchrotron, is able to make C-11 carbon dioxide.
00:39:01.09 C-11 has a half-life of 15 minutes, so you have to be right close to the synchrotron
00:39:05.14 -- you can't ship it very far -- and it allows you to look at very short-term partitioning
00:39:10.21 of carbon in a plant after it's fixed and where is it moving and where it moves it around.
00:39:15.14 And here's just some of the data from Jens' work.
00:39:17.23 He was able to show that. up is transport of C-11-labeled CO2 into young leaves, and
00:39:26.03 you can see that it goes. when you just wound and water a plant. and you treat the
00:39:31.14 wounds with water. the fixed carbon dioxide goes up the plant, but if you add spit to
00:39:36.18 the wound it goes down.
00:39:39.08 And it's the specific FACs in that spit that cause it to go down.
00:39:45.13 And he was also able to show that there's a particular subunit of a SnRK kinase which
00:39:49.24 is regulating that.
00:39:51.01 This is this GAL83 subunit that is down-regulated by the FACs.
00:39:55.06 And that's sort of the. the master sink-source regulator, the genetic element that. that
00:40:01.21 is causing this response.
00:40:04.15 And that bunkering, having put that carbon down below ground into the roots, allows the
00:40:09.13 plant to reflower, make bigger flowers, after the caterpillar has gone.
00:40:14.21 So, in many ways this level, this response, this number five, is a man. is the kind
00:40:21.12 of response that Mahatma Gandhi would have against a predator.
00:40:25.17 You just sort of lay low and let it go by, and don't engage in a fight, but just regrow
00:40:32.18 and be able to start again.
00:40:36.17 Okay.
00:40:37.24 The sixth layer and the last layer is probably the most intriguing layer.
00:40:42.19 It's a type of avoidance of this herbivore and it's an avoidance response that has.
00:40:50.11 has to deal with a fairly common natural history problem that. that all organisms have.
00:40:55.16 And that is that some of their interactions are with good guys and some of them with bad
00:40:59.00 guys, and sometimes the good guy and the bad guy are a part of the same genome.
00:41:03.00 So, this moth is a good guy -- it's a pollinator for the plant -- but it lays eggs that are
00:41:09.05 bad guys, that grow into little herbivores that sometimes turn into very big herbivores,
00:41:13.12 that are very disastrous for the plant.
00:41:16.00 And the sixth response has to do with. with dealing with this herbivore by dealing with
00:41:22.07 its mother, its pollinator.
00:41:24.21 Now, I told you in session 1 that this is a plant that attracts that pollinator by producing
00:41:32.23 a compound called benzylacetone, which is depicted up there above the flower, and.
00:41:37.16 and what Danny Kessler discovered is that when the moth is attracted by that particular
00:41:44.22 structure of benzylacetone, not only is it attracted because of the nectar, it nectars
00:41:50.09 and then it oviposits.
00:41:51.17 So, nectaring and ovaposition are linked processes the more they get nectared by and more visited
00:41:58.16 by this pollinator, the more eggs show up on the plant.
00:42:02.08 The eggs of course turn into herbivores and therefore the more pollination services you
00:42:06.20 get, you might end up getting more herbivores, if the other types of defenses I've talked
00:42:11.12 about earlier aren't effective in cleaning out those herbivores and getting rid of them.
00:42:16.13 Now, we were able to silence benzylacetone production and when we do that we know that,
00:42:21.23 if the plant is not producing benzylacetone, it's pretty much ignored in terms of pollinator
00:42:27.19 activity, and also ovaposition activity by the moth.
00:42:32.05 And Danny Kessler, who is a remarkable photographer but also a remarkable observer of natural
00:42:39.06 history, noticed that attacked plants, when you looked at this. let's do it again at
00:42:43.18 this day night transition. that the plants were beginning to produce a different type
00:42:49.18 of flower after they were attacked.
00:42:52.07 They were producing their normal night flowers, but then they started, when they were attacked,
00:42:55.18 producing a different type of flower that was really only opening in the morning.
00:42:59.24 Now, here is the difference between the morning-open flower on the bottom and the night-open flower
00:43:05.12 at the top.
00:43:06.21 The normal flower is the night-open flower, the one here.
00:43:10.18 And you can see that it opens up in the first night open, and it opens and scents and attracts
00:43:15.22 the moth, and then it closes a little bit for the day, and then opens again and attracts
00:43:19.24 the moth again for the second night.
00:43:22.04 The morning-open flower stays closed that first night.
00:43:25.22 It doesn't scent.
00:43:27.04 And it doesn't attract any moths.
00:43:29.04 And then it opens up just slightly in the next morning, and it attracts a different
00:43:35.13 pollinator, and this is the pollinator -- a hummingbird.
00:43:39.10 And the hummingbird has a very nice characteristic that it lays hummingbird eggs, not caterpillar
00:43:46.08 eggs.
00:43:47.12 And by switching its sexual system to a different pollinator, asking for a different type of
00:43:53.20 postman to bring gametes to you, the plant has basically solved its herbivore problem.
00:44:00.21 And that's pretty remarkable.
00:44:03.07 So, what I've done is told you about all of these changes that occur in the plant when
00:44:10.10 it perceives these compounds here that are in the spit of the plant. the spit of the
00:44:15.13 caterpillar as it chews on. on the plant, and elicits this very complex defense avoidance
00:44:20.14 and tolerance responses.
00:44:22.10 And what I've also told you, I hope. there's basically three messages in behind this remarkable
00:44:28.22 transition that occurs in the plants when it sees these spit factors.
00:44:33.04 The first, of course, is that direct defense is not the only way of coping with herbivores,
00:44:37.10 and most of our agricultural practices dealing with protecting our crop lands have to do
00:44:42.01 with direct defenses -- insecticides that directly kill the crop press. the crop pests.
00:44:48.10 Now, as we've learned from this story, there's many other ways of dealing with your herbivore.
00:44:53.14 And we should be thinking about how to incorporate some of those many other ways into our cropping
00:44:58.11 systems, because some of them may well be much more evolutionary stable than just using
00:45:02.22 direct defenses alone.
00:45:05.10 The second main take-home message that I want to get from this is this interplay of the
00:45:09.08 importance of knowing mechanism so that you can use mechanisms to be able to manipulate
00:45:14.20 function.
00:45:16.12 And when you can manipulate function you can begin to ask, in an unbiased way, what is
00:45:21.03 actually happening in nature between plants and insects, and all the other interactors.
00:45:26.23 And the third main message I want you to get from this is that you can observe an awful
00:45:32.02 lot by just watching.
00:45:33.15 Now, this little tautology is something from Yogi Berra, but I think it applies so cogently
00:45:40.14 to biology today, because we don't teach our students how to watch, particularly not natural
00:45:49.06 interactions, anymore.
00:45:50.06 This is not part of our biological training programs.
00:45:53.08 And so much of the innovation that I've just shown you comes from simple natural history
00:46:00.11 observations.
00:46:01.23 Okay.
00:46:03.11 So, in the third part. that was the end of the second part, in the third part I'm
00:46:08.02 going to talk about seeds, sex, and microbes.
00:46:11.08 In Part 1, I told you that this is a plant that chases fires, it produces seeds that
00:46:16.13 have to live in the seed bank for hundreds of years before the next fire comes along,
00:46:21.09 and I'm going to be talking about how it uses sex to get the best genetic material, to be
00:46:25.24 able to survive that long-time period of. as it waits for the next germination event,
00:46:33.08 and also how it recruits microbes when it does decide to. to. to germinate in opportunistic
00:46:39.08 mutualisms to help protect it against all sorts of stresses that you could hardly predict
00:46:43.14 if you had been in the seed bank for hundreds of years.
00:46:46.07 So, I want to thank you for your attention, but I particularly want to thank both the
00:46:51.04 funding organizations that make this work possible, the long-term, patient funding of
00:46:56.00 the Max Planck Society, and the grants we received from these wonderful agencies that
00:47:01.02 are so unbureaucratic in their administration, and really promote curiosity-driven science
00:47:06.12 in the best way possible.
00:47:07.23 I want to thank the folks at Brigham Young University, particularly Dr. Larry StClair,
00:47:12.22 Ken Packard, and Heriberto Madrigal, that make this wonderful interaction with that
00:47:17.23 remarkable University work, and allow us to use their Lytle Ranch Preserve as a laboratory
00:47:24.09 to study, for the site of these field interactions.
00:47:27.01 And I want to talk.
00:47:28.01 I want to thank all the people who have provided the stunning pictures and movies, the talented
00:47:34.13 photographers and. and folks in the group who have helped support and make some of these
00:47:39.07 slides.
00:47:40.07 And, particularly, Erna Buffie and Volker Arzt, who are really masters of translating
00:47:47.22 science, making beautiful movies, and allowed us to use many of their outtakes from their
00:47:53.03 movies in this presentation.
00:47:55.08 And, you, for your attention.


Identify

Correctly identify ing such trends means being able to plan in advance and then taking advantage of heightened interest.

Reporters Sapien and Sanders worked with Willis to identify several high-ranking NYPD commanders who had been promoted again and again despite long records of serious civilian complaints.

First, the team worked to identify whether they had assigned the most relevant URLs for the keywords.

If scientists are able to identify an immune correlate of protection, however, “and you can demonstrate that kids get that with the vaccine, that’s even more satisfying,” O’Leary said.

The funds were to be transferred to the CPUC quarterly, but the CPUC didn’t try to identify whether any of that money was outstanding.

We have thousands of users who identify themselves as transgendered and they are welcome members of the Grindr community.

He loves the fact that, like on Grindr, users can identify as transgender.

But most likely it was linked to the way priests identify with the poor in the face of government and criminal abuses.

Certainly my instinct is to identify with the police, no matter the circumstance.

The others are difficult to identify , since they reacted with other oxygen-bearing molecules in the soil.

Ordinarily, no attempt is made to identify any but the tubercle bacillus and the gonococcus.

All the same, she was quite at a loss to know how she was to identify the General Maxgregor when he did come.

In some cases proper evidence may be used to identify things where the description in the will is ambiguous.

The thing bequeathed must be described with sufficient clearness to identify it, nothing more is required.

However, both let it pass, and no one through the whole school attempted to identify it.


Identify the wild Plants of Western North America

To appreciate the plants of western North America, one must become intimate with the landscapes in which they live. Let Mountain Nature Network be your source for the plants of western North America.

Learn to Identify Plants. The Rockies have a fabulous diversity of plant life. Let Mountain Nature Network help you learn the skills to become an expert and identifying these plants.

Identify a Plant. Mountain Nature Network offers more ways to identify the plants of the Rockies than any other web site. No book can compare with the simplicity you will find here.

Search for recent sightings. Our sightings database allows you to search for sightings of any of our growing list of plants. This can help you reduce the challenge of finding an new species for your life list.

Record your sightings. Any sighting worth having is also worth recording. Use our interactive sightings database to record your sightings, view your life list and contribute to the work of researchers studying the plants of the Rocky Mountains.


Carbohydrates

Carbohydrates are the most common type of organic compound. A carbohydrate is an organic compound such as sugar or starch, and is used to store energy. Like most organic compounds, carbohydrates are built of small, repeating units that form bonds with each other to make a larger molecule. In the case of carbohydrates, the small repeating units are called monosaccharides. Carbohydrates contain only carbon, hydrogen, and oxygen.

Monosaccharides and Disaccharides

A monosaccharide is a simple sugar such as fructose or glucose. Fructose is found in fruits, whereas glucose generally results from the digestion of other carbohydrates. Glucose(C6H12O6) is used for energy by the cells of most organisms, and is a product ofphotosynthesis.

The general formula for a monosaccharide is:

where n can be any number greater than two. For example, in glucose n is 6, and the formula is:

Another monosaccharide, fructose, has the same chemical formula as glucose, but the atoms are arranged differently. Molecules with the same chemical formula but with atoms in a different arrangement are called isomers. Compare the glucose and fructose molecules inFigure below. Can you identify their differences? The only differences are the positions of some of the atoms. These differences affect the properties of the two monosaccharides.

Sucrose Molecule. This sucrose molecule is a disaccharide. It is made up of two monosaccharides: glucose on the left and fructose on the right.

If two monosaccharides bond together, they form a carbohydrate called a disaccharide. An example of a disaccharide is sucrose (table sugar), which consists of the monosaccharides glucose and fructose (Figure above). Monosaccharides and disaccharides are also called simple sugars. They provide the major source of energy to living cells

Polysaccharides

A polysaccharide is a complex carbohydrate that forms when simple sugars bind together in a chain. Polysaccharides may contain just a few simple sugars or thousands of them. Complex carbohydrates have two main functions: storing energy and forming structures of living things. Some examples of complex carbohydrates and their functions are shown in Table below. Which type of complex carbohydrate does your own body use to store energy?


Identification of the DCL family in Gossypium

The genome sequences of three cotton species, G. arboreum (BGI-CGB v2.0 assembly genome), G. raimondii (JGI assembly v2.0 data) and G. hirsutum acc. TM-1 (NAU-NBI v1.1 assembly genome), were downloaded from the Phytozone (http://www.phytozone.net/) and CottonGen (https://www.cottongen.org/) databases. Dicer-like protein sequence data were obtained for A. thaliana and O. sativa from the General Feature Format (GFF) le Arabidopsis Information Resource (TAIR release 10, http://www.arabidopsis.org) and from the Rice Genome Annotation Project Database (RGAP release 7, http://rice.plantbiology.msu.edu/index.shtml). Gene names and IDs are listed in Additional file 1 and in Additional file 2: Table S1).

The physico-chemical properties of cotton DCL proteins were predicted using the ExPASy Compute pI/Mw tool (http://au.expasy.org/tools/pi_tool.html Bjellqvistetal Bjellqvistetal, 1993).

Chromosomal location analysis and phylogenetic tree construction

The locations of the DCLs in chromosomes were assessed using Mapinspect software (http://www.softsea.com/review/MapInspect.html) using start and end position of each open read frame obtained from the genome database. .

A phylogenetic tree was constructed using MUSCLE (Multiple Sequence Comparison by Log-Expectation) alignment and the neighbor-Joining (NJ) method in MEGA 7.0 software [72], with the 1000-replicate bootstrap test. A keyword search of the Phytozome v12.1 database (https://phytozome.jgi.doe.gov/pz) and National Center for Biotechnology Information database - NCBI (https://www.ncbi.nlm.nih.gov) was further performed to obtain the DCL genes in different plant organisms.

Intron–exon and domain analysis of the DCL family

The Gene Structure Display Server (http://gsds.cbi.pku.edu.cn/index.php) was used to analyze the intron–exon structure by comparing the CDS of cotton DCL genes with their corresponding genomic sequences [45, 73]. The conserved domains in the DCLs were identified by SMART (http://smart.embl-heidelberg.de).

Plant materials

Two upland cotton G. hirsutum cultivars were used for the DCL expression assays and viral infection: acc. FiberMax966 (FM966) (Aventis Crop Science, Australia) and acc. Delta Opal (DO) (Delta and Pine Land Co., United States). Seeds were kindly provided by IMA, Instituto Matogrossense do Algodão, Primavera do Leste, Mato Grosso state, Brazil. Plantlets were grown under greenhouse conditions at 28 +/− 2 °C as previously described [49].

For cotton organ DCL expression, samples of leaves, shoots, flowers, and roots from independent plants at 30 days after germination (dag) were collected from each cotton acc. FM and DO. Samples were immediately frozen in liquid N2 and stored at − 80 °C until RNA extraction.

Plant aphid inoculation and virus infection

Cotton (Gossypium hirsutum) plants of cultivars acc. FM966 (susceptible to Cotton blue disease) and acc. DO (resistant to Cotton blue disease) grown in the greenhouse and at the 30 dag stage were infected with Cotton leafroll dwarf virus (CLRDV, polerovirus, Luteoviridae family) by viruliferous aphids (Aphis gossypii Glover) as described previously [56]. Full-developed leaves of plants with the same age from both cultivars were inoculated with non-viruliferous aphids (virus free aphids). Aphids were restricted at the inoculation site by double-side adhesive tapes (3MM Co.) and killed 24 h after inoculation with insecticide. Aphids were restricted to the inoculation sites at the inoculated leaves by surrounding the inoculation site with a double face tap.

Systemic leaves, localized 3–4 leaves above the inoculated leaf, were collected at 24 h post-infection (hpi) and 5, 15 and 25 days post-infection (dpi) with CLRDV aphids or non-viruliferous aphids. Leaves from the same position of uninfected plants were used as uninoculated controls. Leaves from 3 to 5 independent inoculated plants composed each biological replicate. Samples were stored at − 80 °C until RNA isolation and expression analysis.

All the samples recovered from aphid-free inoculated, CLRDV infected and uninoculated were assayed for CLRDV detection by a Nested RT-PCR assay that amplifies viral coat protein sequence following [53]. CLRDV susceptible infected plants were used as control.

Real-time quantitative RT-PCR (RT-qPCR)

Total RNA was isolated using the Invisorb Spin Plant RNA Kit (Invitek Molecular Co., Germany). The quality and concentration of each RNA samples was determined by agarose gel electrophoresis and using a NanoDrop 2000 (Thermo Fisher Scientific Co.) spectrophotometer. Only RNA samples with a 260/280 nm ratio between 1.8–2.1 and 260/230 ratio ≥ 2.0 were used. The c-DNA first-strand reverse transcription was conducted with the Revertaid First Strand cDNA, Synthesis Kit (Thermo Fisher Scientific Co.) in accordance with the manufacturer’s instructions. One microgram of total RNA from each sample was treated with DNAse I (Fermentas Co.), and cDNAs were synthetized by adding 100 μM of oligo dT24V primer. G. hirsutum DCL reverse and forward primers were designed using NCBI primer-BLAST (Additional file 2: Table S2). Maxima SYBR Green/ROX qPCR Master Mix (Thermo Fisher Scientific Co.) was used to perform RT-qPCR in a 7500 Fast Real-Time PCR System (Applied Biosystems), in accordance with the manufacturer’s instructions. The cycling conditions were 10 min at 95 °C for initial denaturation, followed by 40 cycles of denaturation at 95 °C for 15 s and annealing/extension at 60 °C for 30 s. Cotton GhmiR390 and GhPP2A (catalytic subunit of phosphatase 2A) were used as reference genes for the analysis of DCL expression in different organs, the results were obtained by △ CT method and the 2 − △ △ CT method was used to analyze DCL expression during viral infection and/or aphid inoculation [51, 52]. Cotton GhmiR390 and GhPP2A (PROTEIN PHOSPHATASE 2), which were previously identified as the best reference genes for CLRDV infected cotton studies [74], were used to normalize cDNA expression levels. Reactions were prepared in a total volume of 20 μL, which contained 10 μL of SYBR green master mix, 2 μL of cDNA template, 6 μL of ddH2O, and 2 μL of each primer to make a final concentration of 10 μM. Three biological replicates were performed, and three technical replicates were assayed per cDNA sample.

In order to show DCL expression in each organ, a heat-map of the DCLs expression pattern was established by complete clustering method analysis using Euclidean distance and calculated in the R software environment. The DCL Cts results are shown at Additional file 2: Table S3.

Sequencing of CAV sviRNAs by deep sequencing

Leaves of cotton infected with Cotton anthocyanosis virus (CAV) obtained in Mato Grosso state, Brazil, were used for total RNA extraction and small RNA purification and sequencing by Illumina plataform following procedures described by [54].

Statistical analysis

DCL relative expression levels determined for the different samples under herbivore attack and/or virus infection were compared with these controls: untreated plants (control) x aphid inoculated plants for herbivore expression analysis, and mock (virus-free aphids inoculated plants) x CLRDV-aphid inoculated plants for viral infection using the parametric one-way ANOVA test at P ≤ 0.05 and P ≤ 0.01. For checking if the different relative expression levels of DCLs, from FM and DO, are statistical significant T-student test were used.

Promoter region cis-acting element analysis

For the identification of cis-regulatory elements present in G. hirsutum DCLs, upstream sequences of 1500 nucleotides from ATG star codon were downloaded from the CottonGen website (https://www.cottongen.org) and cis elements predicted with PlantCARE software (http://bioinformatics.psb.ugent.be/webtools/plantcare/html/).


Watch the video: Τα TOP 5 Πιο Επικίνδυνα Και ΘΑΝΑΤΗΦΟΡΑ ΦΥΤΑ Στον Κόσμο. TopTenGR (February 2023).