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It’s the Pits with Dr. Andrei Smertenko

Posted by Blythe Howell | July 20, 2020

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Show Notes & Resources Mentioned:

Contact Information:

Contact Dr. Andrei Smertenko via email at or via phone at (509) 335-5795.

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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 from 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. Andrei Smertenko. Andrei is a cell biologist at the Institute of Biological Chemistry in the College of Agricultural, Human, and Natural Resource Sciences. Andrei joined WSU over six years ago. Andrei wants to understand how cells respond to drought stress, and how we can harness processes inside cells to improve crop yields in arid climate. Hello, Andrei.

Dr. Andrei Smertenko: Good morning, Drew.

Drew Lyon: So, our last guest was Dr. Sanguinet, your collaborator and so very interesting work that was talked about in the Spokesman Review back in– in May, which I found very interesting, so that’s why I invited you to come. Can you tell us a little bit about this new work?

Dr. Andrei Smertenko: Yeah, so in broader sense, our work addresses the mechanisms of plant movements through plant body. We all know that water is important for plant life. In particular it– it is an essential component of photosynthesis. So, plants use a lot of water and without water plant life will stop. We use water in quite a lot by irrigating our fields and we can substantially increase the yields by putting more water on plants. And the way it works, the more water the higher is yield. But then, we– we have very little understanding what happens after water is soaked into the soil. And so, this is work that we are trying to address in collaboration with Dr. Karen Sanguinet’s lab.

Drew Lyon: Okay, so this water is kind– and how it moves through a plant is kind of similar to how blood moves through our bodies. Is that an appropriate analogy or are there important differences?

Dr. Andrei Smertenko: Yeah, we can probably say so; there are a lot of similarities. In a human body, blood moves through blood vessels and carries together with it nutrients and oxygen and it takes away carbon dioxide and products through their metabolism. In plants, water and minerals move through specialized cells that are called vascular cells. So, water is uptaken into plants through roots. And then in roots get into the vascular cells inside roots, and these cells are connected to the very wide web of vascular cells in all plant organs through which water and minerals will get there. But then there are also quite a number of significant differences. And first of all, how extensive is muscular system within plants? So, if you put together all blood vessels and capillaries if they have in the human body, we will have about 100,000 miles of vessels. That’s pretty impressive number.

Drew Lyon: That is a large number.

Dr. Andrei Smertenko: But if you add all muscular cells in plant body, we will have about 90 million miles, which is almost the distance between earth and sun. And it exemplifies how important is water movement in a plant body. So, they invest so much energy to construct very extensive system of water supply vessels.

Drew Lyon: Okay. These vascular cells, are they easy to see in plants?

Dr. Andrei Smertenko: Yeah, in fact, yes. So, if we will cut through a tree, we will see wood, and wood, in fact, made of vascular cells. In a way, plants are very clever with using these cells. So, on the one hand, they use vascular cells to transport water and minerals through their body. But on the other hand, they use them to support the weight of their body, because in order for tree to grow and keep the weight of the shoots it has to be pretty strong, and vascular cell, in addition to being able to– to conduct liquids they’re all very tough cells; they make plant body very strong.

Drew Lyon: Okay, so, again, they transport things, but they’re a little bit different than our blood vessels because they– our blood vessels don’t give us any strength. So, can we still apply our knowledge about blood circulation to understanding water movement in plants?

Dr. Andrei Smertenko: Not quite. Despite lots of similarities between how the blood is moved through human body and how is water moved through plant body, there are a number of profound differences. And the first one is what drives the movement of liquids. In our body we have heart that works very hard to pump blood through all the vessels. And in plants they have transpiration. Transpiration is evaporation of water from the leaf surface through very tiny openings called stomata. Evaporation of water creates negative pressure inside the vascular cells and then this negative pressure drives water movement through the whole vascular system from root all the way up to the– to the shoots. And another important difference is morphology of the vessels. In human body, blood vessels are hollow, and so it doesn’t obstruct the movement of blood, whereas, in plant cells, vascular cells are actually individual cells, just connected to each other. And in order to move through plant body, water has to passage through cell to cell by a specialized force, which are called pits.

Drew Lyon: Okay, so if the vascular– if the vascular system consists of these individual single cells, how can water move such long distances within a plant?

Dr. Andrei Smertenko: Yeah, so the pressure generated by evaporation is a very important factor. And another one of those small connections between vascular cells, which are called pits. So, pits is a– in a way, is modification of the cell wall that surrounds the plant cell and they’re much thinner than the rest of the cell wall. And inside the pit we have like a tiny mesh. This mesh allows both minerals to move through plant body, but it prevents passage of microbes, say that could accidentally get inside the– the vascular cells. In– in the human body, we have immune system that would deal with all bugs, all like microbes or viruses if they get inside the– the blood vessels, but plants don’t have immune system. So, the way to protect themselves from spreading all the kind of pathogenic organisms is reducing the– the passage through the vascular cells.

Drew Lyon: Okay. So, do bigger pits allow faster water movement, which in turn might support faster plant growth, better photosynthesis?

Dr. Andrei Smertenko: Yeah, so ab– absolutely. Under good irrigation conditions, bigger pits would facilitate water movement through the plant, resulting in a more efficient photosynthesis, more efficient carbon dioxide assimilation and greater yield.

Drew Lyon: Okay, so under well water conditions, but what about dry climates, like we have here in Eastern Washington?

Dr. Andrei Smertenko: Yeah, under arid climates, big pits could spell a significant problem for plants. This is because of the negative pressure that is created inside the vascular system through evaporation cannot be compensated by the supply of water through roots in drought conditions. And this negative pressure inside vascular cells would create air pockets, which are also called embolism. So, embolism blocks the particular vessel and it prevents water movements. Of course, as we discussed, plants have millions and millions of vessels, so if one vessel is blocked it’s not a big problem. But then the– the problem is that air pockets can spread from one vascular cell to another vascular cell through pits, and the size of the pits is proportional to the efficiency of spread of these air pockets. In another word, the bigger pits the faster is going to be spread of the air pockets. And then if, eventually, all vascular cells will be blocked, then the water passage through plant body will be completely inhibited. And then even if the drought period will be over and the rain will start, plant will not be able to recover.

Drew Lyon: Okay. Reminds me of syphoning– I should say that– syphoning gas or syphoning something and getting an air bubble in there and not being able to move water because of it. So, the same sort of thing happens inside the– inside the plant.

Dr. Andrei Smertenko: Yeah, absolutely.

Drew Lyon: Okay.

Dr. Andrei Smertenko: And so, under arid climate, having smaller pits can offer significant advantage. And, in fact, research shows that plants grow in a well irrigated area have larger pits, whereas plants which are adapted to grow in arid climate have much smaller pits.

Drew Lyon: Okay, so– so, can we use this knowledge to make plants more drought tolerant? In other words, make plants with smaller pits, would that make them more drought tolerant?

Dr. Andrei Smertenko: Yeah, indeed. So, now we come in to understanding that drought tolerance is a very complex trait and it requires adjustment of many different aspects of plant physiology. And of course, one very important aspect to increase efficiency of photosynthesis under drought, but another important aspect is optimizing plant body morphology, so it can handle water more efficiently. And in combination with other biochemical processes could sustain greater yield under used water availability. And I think morphology of pits is a very important aspect of this engineering work.

Drew Lyon: Okay, so is it really possible to manipulate or control the structures in a plant?

Dr. Andrei Smertenko: It would be very tempting possibility. At the moment we are learning about how pits are made. We identified one of the components in collaboration with Dr. Karen Sanguinet’s lab. Other labs in the world have also been very successful finding genes that are important for the construction of pits. And now we are trying to build a general picture about how plants do it. And once we have mechanistic understanding of this process then we will be able to develop technologies for engineering pit size to optimize it for particular environmental conditions. And certainly, for varieties that we develop for the central Washington state, reducing pit size would provide a lot of benefits.

Drew Lyon: Fascinating. That– the whole idea of pit size and drought tolerance, I’ve not seen those two things come together before, so it’s– to me, it’s fascinating how complex drought tolerance is and how the more we learn about plants and basic physiology the more we can understand how plants adapt to– to this stress.

Dr. Andrei Smertenko: Yes, absolutely. I think our goal is to develop a set of technologies that we can apply to solving particular problems in adapting varieties to particular growth environments. And once we have one of this portfolio of tools we will be able very efficiently to apply to all necessary situations.

Drew Lyon: Well, thank you very much for sharing your– your research on this fascinating topic. If our listeners want to learn more, is there a website they can go to or a particular place they can visit to see more of what you’re doing?

Dr. Andrei Smertenko: Yes, they can visit my website at the Institute of Biological Chemistry.

Drew Lyon: Okay, and how– do you know the URL for that site?

Dr. Andrei Smertenko: I will provide the site later.

Drew Lyon: We’ll get that in our show notes for our listeners [Background Music].

Dr. Andrei Smertenko: Right.

Drew Lyon: Thank you very much for your time Andrei.

Dr. Andrei Smertenko: Thank you very much for having me here on the podcast, Drew. It was very– it was a pleasure to talk to 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 –( You can find us online at 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.

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