Tillering in Wheat with Dr. Kulvinder Gill


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Show Notes & Resources Mentioned:

Contact Information:

Contact Dr. Kulvinder Gill via email at ksgill@wsu.edu or via phone at 509-335-4666.

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Episode Transcription:

Drew Lyon: Hello. Welcome to the WSU Wheat Beat podcast. I’m your host, Drew Lyon, and I want to thank you for joining me as we explore the world of small grains production and research at Washington State University. In each episode, I speak with researchers WSU and the USDA-ARS to provide you with insights into the latest research on wheat and barley production. If you enjoy the WSU Wheat Beat podcast do us a favor and subscribe on iTunes or your favorite podcasting app and leave us a review while you’re there so others can find the show too.

[ Music ]

Drew Lyon: My guest today is Dr. Kulvinder Gill. Kulvinder is a professor of genetics from the Department of Crop and Soil Sciences at Washington State University with a focus on wheat, his research program focuses on understanding genetic and molecular mechanisms controlling agronomic important traits of wheat and translating that information into developing novel technologies for crop improvement. Recently, he has been understanding traits controlling heat stress tolerance in wheat and developing germplasm and markers for its selection. Hello, Kulvinder.

Dr. Kulvinder Gill: Hello, Drew.

Drew Lyon: So, your groups kinda been working lately on understanding the tillering trait of wheat. Why are you interested in that trait?

Dr. Kulvinder Gill: Yeah, tillering trait is very important for yield because it allows fewer seed to make more spikes. But at the same time, more tillers are not always better. If you look at old varieties, they will set ten tillers, two or three will be productive, and then others non-productive tillers are wasting other very valuable resources. So, the ideal tiller number is that the fewer tiller, all equally productive. So that’s the way of understanding the trait and a mechanism will allow us to make sure that whatever tiller the plant sets they are equally productive and valuable.

Drew Lyon: Okay, so my understanding of tillering, it’s part of the plant’s plasticity. So, it’s reacting to the environment. So, if you limit that number, does the plant still adjust to the different — I mean, one reason wheat’s on so many acres is it’s able to handle all sorts of different environments and still produce. So, I’ve often discussed, are you better off with fewer tillers or more tillers? And I guess I’m kind of curious about that.

Dr. Kulvinder Gill: So, wheat is a grass, right? So, as we know, grass can set pretty much an unlimited number of tillers. And then the ancient day, the wild relatives of wheat there are in that category, they can set a lot of tillers. But that is not a good trade. If other tillers don’t produce as much as the main tiller. So, the question you raised out of the more or the less better, I say most important part is as many tillers as we can set that are equally productive without wasting our resources is an ideal number. And that ideal number may change in the end. The number may be different than in Palouse. So, and then if we grow wheat specific variety in a controlled condition, it is a highly stable trade. But in the natural environment, especially like in this year, number of tiller pretty much shrunk to half. So it’s very responsive to environment.

Drew Lyon: Okay, so what what’s your group been finding about the tillering trait?

Dr. Kulvinder Gill: So, we — our group, because wheat is such a complex genome, we try to use information from model systems like Arabidopsis or rice, and then see if we can know more about wheat trait. So in this case, we cloned a gene that actually controls tiller. So, what we have learned is that this gene expression is at the crown of the plant. That’s where the growing tip is. And we learned a lot about the wheat plant. Also, we always thought that wheat growers, as the plant grows, but no, the growth happens at the base and then the leaves just extend. And that’s why that you can keep cutting the leaves from the top and it keeps growing because the growing tip is hidden in the crown. So, this gene expresses there and a controlled number of dealers and the initiation of it. So it controls how many tiller parts are going to be made. And it has some role to play in the extension of that tiller, although many other hormones are involved in that process. We are a long ways to go before we completely understand, because the extension of the site tillers will determine how productive that tiller is going to be if it is a weak tiller, it is going to set weeks spike, and then that the energy it will take probably be the same as the good, healthy tiller, so we want the other energy going into good, productive tiller rather than a weakling.

Drew Lyon: Okay, so you’re trying to figure out how to get the plant not to develop those weak tillers.

Dr. Kulvinder Gill: So but once it is initiated or differentiated, then we want it to develop into a normal, fertile tiller.

Drew Lyon: Okay.

Dr. Kulvinder Gill: And we will I mean, I’ll take 20 tillers any day if they’re equally productive.

Drew Lyon: Okay.

Dr. Kulvinder Gill: That way we can cut the seed rate to one third or less.

Drew Lyon: Okay, so you’ve been talking, as we’ve been talking here about the number of tillers and the number of spikelet’s, or heads in the same sentence. What’s the connection between tillers and spikelet’s?

Dr. Kulvinder Gill: Yeah. I mean, before this project, personally, I always thought that, okay, tillers initiated two to three leaf stage and then the spikes differentiate much later. To our surprise, both happened pretty much at the same time. So even the spike differentiation or the spikelet’s, they also differentiate very early during the plant development. And why it is important? Those spikelet’s are sockets were grains will be filled. The more sockets means more an option to have more grain’s in the spike. Although the process that how many grains actually get filled is a separate discussion. But if we don’t even have room to set those seed then — So spikelet number it’s very, very important trait for yield. And what we found was the same gene control both traits. So, we didn’t know that before. We found that while we were studying to link to it.

Drew Lyon: Okay, so with this one gene, you can control both very important processes.

Dr. Kulvinder Gill: And they respond both ways. That in the same direction. That is if we get more to learn and then it has more spikes also. And although we found that the same gene by manipulating genes promotor, we can have it expressed more in the for spike development, less for fertilizer and vice versa. So there is room to manipulate and differentiate for these two very important traits versus the same gene.

Drew Lyon: Interesting, so explain to me how this finding translates into something that the growers can appreciate.

Dr. Kulvinder Gill: Yes. [ laughter ] So, as I said, that wheat is a very complex trait with 100,000 genes, and each gene, there are many different aspects of it. So, once we understand this gene, we will be able to manipulate what are the ideal number of tillers that come up with. So, we simply put initially, we may develop a marker that can tell us, okay, if we select this type of marker, the plant will have four tillers that will do good and say the Lind area. And that is possible once we understand this. Are we there yet? No, we are working on it. There we follow experiments. But that is the hope that when we understand this process completely, then not even completely early on, also as we learn. My focus is always on application. So, we look for ways how we can use that information for crop improvement while we are learning more about that trait. So initially, the focus is we will develop a marker that breeders can use to select ideal tiller number for different environmental conditions.

Drew Lyon: Okay. I could, you know, just thinking about it here briefly. I could see the world like an irrigated situation where, you know, you’re going to have so much water, you can kind of predict how many tillers or spikelet’s your plant — you want the plant to develop. And as you get into more drier environments, maybe it’s a little more difficult to predict, but you can pick a different number. Like, would irrigated be just one tiller? [ laughter ] Might be the optimum of just plant at a high seed rate and get a really productive tiller?

Dr. Kulvinder Gill: I mean, my personal preference would be a lot of tillers equally productive.

Drew Lyon: Okay.

Dr. Kulvinder Gill: So that we can cut the seed rate, because right now we need a lot of seed, which is expensive item for farmers. So, I mean, I’m always greedy. I want more tillers, but equally fertile. So, then we can actually reduce the seed rate and still harvest the same crop even better.

Drew Lyon: Okay, very good. So, what are the next steps in the project?

Dr. Kulvinder Gill: So, the first as I said, that application is a pretty important part with whatever we do in our lab. So I want to know what is an ideal tiller number in different environments and also especially under heat. We’ve been doing quite a bit of work under the seed project that how do tiller numbers respond at elevated temperature? And at the site do tiller growth to the same or does it get compromised? And one thing we learned that plant knows, which is meant to learn, which is site tiller, that was pretty exciting for us to know. And so that gives us that we can separate of the site tillers from mantle. So we will have to first understand how this gene respond under different environments. And that will give us a clue that can we develop a marker for this gene for breeders to use when they’re breeding for different environments, like, for example, of low rainfall, we may be able to develop there, say, okay, if you select for a plant having this much expression of this gene, then you are likely to find an optimal number tiller number for a particular environment. That’s the goal — immediate goal. And the longer term we want to understand the molecular mechanism is interaction with other hormones so that we can actually engineer an ideal plant with the ideal number of tillers and ideal number of spikelet’s.

Drew Lyon: That’s very interesting and exciting stuff. If our listeners wanted to find out more about this, is there a place they can go to learn about what’s happening in your lab?

Dr. Kulvinder Gill: The paper is under review, but they can always call me. And because the information we put on the website is very limited since it’s one page.

Drew Lyon: Okay.

Dr. Kulvinder Gill: But until the paper publishes and even like growers may not be interested in reading this 15-page paper, they can just the best way is probably just to call

Drew Lyon: Okay. And we’ll make sure to put your contact information in the show notes. Thank you, Kulvinder.

Dr. Kulvinder Gill: Alright. Thank you.

[ Music ]

Drew Lyon: Thanks for joining us and listening to the WSU Wheat Beat podcast. If you like what you hear don’t forget to subscribe and leave a review on iTunes or your favorite podcasting app. If you have questions or topics, you’d like to hear on future episodes please email me at drew.lyon — that’s lyon@wsu.edu –(drew.lyon@wsu.edu). You can find us online at smallgrains.wsu.edu and on Facebook and Twitter @WSUSmallGrains. The WSU Wheat Beat podcast is a production of CAHNRS Communications and the College of Agricultural, Human and Natural Resource Sciences at Washington State University. I’m Drew Lyon, we’ll see you next time.

The views, thoughts, and opinions expressed by guests of this podcast are their own and does not imply Washington State University’s endorsement.