It was four years ago when the University of Missouri and the Donald Danforth Plant Science Center entered into a collaborative agreement that would lead to the hiring of four new researchers, each of whom would enhance the plant biology research not only in the state, but also across the globe.
Three of those positions are now filled, with the recent additions of R. Keith Slotkin and Bing Yang, joining Blake Meyers, who was the first collaborative hire in 2016.
“Plant biology is a major strength of this campus – and a major strength in St. Louis,” said Bob Sharp, a professor in the Division of Plant Sciences and director of MU’s Interdisciplinary Plant Group (IPG). “Linking the MU plant community with the St. Louis plant community was an obvious strategy. The objective was to build a formal link between the two institutions to facilitate partnerships, collaborations, graduate student and post-doc training, and grant opportunities. The opportunities were there anyway, but to have people linking the two institutions is key to greater collaboration. They create a bridge that everyone can cross. We’re thrilled to now have three of those individuals on board.”
Before the formal agreement for joint hires, MU and the Danforth Center were already familiar with each other. Several Danforth scientists are adjunct professors at Mizzou, and the two institutions had collaborated on various grants as well. The joint hires were part of a push for several targeted and strategic hires in plant biology at MU. All of the hires would be Mizzou professors, but with two to be located at the Danforth Center and two at Mizzou.
“These were strategic hires targeted toward specific scientists who could choose their academic home, so there was an obvious role for the campus-wide IPG to play in their recruitment,” Sharp said.
Meyers, whose MU appointment is as a professor in the Division of Plant Sciences, was on the initial shortlist of individuals MU and the Danforth Center wanted to bring in. Meyers was serving as the Edward F. and Elizabeth Goodman Rosenberg Professor in the Department of Plant and Soil Sciences at the University of Delaware before taking the first of the four positions.
“It was a combination of factors that led me to take the position,” Meyers said. “The joint nature of the position was extremely attractive. The fact that I could be a bridge for both institutions was a key. I had always worked as a faculty member at a university, so coming to a private non-profit was kind of a leap for me. The opportunity to keep one foot in a traditional university department was appealing. Overall, I was thrilled to work with both institutions and their faculty, students and scientists.”
Meyers’ research focuses on genome-scale studies of ribonucleic acid (RNA) and components of RNA silencing pathways. His recent emphasis has been on plant reproductive biology and fertility, with the main work of the lab on the evolution and function of plant small RNAs.
“The experience has been fantastic so far,” Meyers said. “There have been some challenges, as the first joint hire, but these have been minor, and people at both institutions have been quite helpful. I’m thrilled to have Keith and Bing join as colleagues. I’ve known them both for awhile, and I’m excited to have them join us, as there are many opportunities for collaboration.”
Slotkin officially began on August 1; Yang began on September 1. Slotkin will serve as an associate professor in the Division of Biological Sciences. Yang’s appointment is as a professor in the Division of Plant Sciences.
“To have Keith and Bing join us is really exciting,” Sharp said. “We’ve been working hard to recruit additional key scientists ever since we hired Blake, and we feel very fortunate to now have three of the positions filled.”
Slotkin’s research centers on the area of epigenetics – understanding how plant cells determine which regions of their DNA should be active or repressed. Slotkin said if you think of DNA as a blueprint or instruction booklet, epigenetics serves as the legend that informs you how to use that blueprint.
“Epigenetics is not the ATGC letters of the DNA, but it’s the information that is associated with the DNA,” Slotkin said. “How does an individual plant cell know what to become, to become a leaf or become a root? Those instructions come along with the DNA information from the previous cell.”
Slotkin was an associate professor in the Department of Molecular Genetics at The Ohio State University before joining MU and the Danforth Center.
“For me, I had never heard of such a unique opportunity,” Slotkin said. “In my world, individuals want to be associated with universities because that brings a certain set of tools to the game. Being a part of an institute brings another set of tools. This joint position looks like the best of both worlds.”
Yang served as an associate professor in the Department of Genetics, Development and Cell Biology, College of Liberal Art and Sciences at Iowa State University. His research focuses on advanced biotechnologies that provide genetic and molecular tools to help with the basic understanding of plant biology.
“This is a great opportunity to work with numerous distinguished individuals at both institutions,” Yang said. “The environment at both MU and the Danforth Center is exceptional. Being a joint hire between the two opens up great opportunities for successful research and a chance to make bigger impacts on the world.”
Yang is the first of the hires to be housed at MU, and is located in the Bond Life Sciences Center. Meyers and Slotkin are both located at the Danforth Center.
“I’m excited to work on campus,” Yang said. “There is great technology at MU, and I’m excited to utilize that technology. It’s a great plant community and I’m thrilled to be a part of it.”
While the joint hires will serve as a bridge for extended opportunities for collaborations, MU and the Danforth Center are already making an impact with two recent grants through the National Science Foundation. The grants total nearly $5 million.
How Plants Sense Iron
When David Mendoza-Cozatl joined the University of Missouri in 2011, he began researching how plants accumulate nutrients. While Mendoza-Cozatl was primarily interested in how nutrients move within plants, he happened upon another discovery – how plants sense nutrients, like iron.
“We don’t really know how nutrients are sensed,” said Mendoza-Cozatl, an associate professor in the Division of Plant Sciences. “Zinc and iron, for example, are critical for life and are both reactive, meaning you need them but only in the correct amount. High concentrations of either can be toxic.”
Traditionally, it was thought that iron sensing happened in the roots of the plant. The roots are in close contact with the iron sources in the soil, making it seem as though the sensing would happen in that area. Preliminary data found in Mendoza-Cozatl’s laboratory, and other laboratories, shows that iron sensing also happens in specialized cells, known as companion cells, located in the leaves.
“There are some dead tubes inside the plant, xylem, that help move nutrients and other molecules from the root to the leaf,” Mendoza-Cozatl said. “These tubes move things in only one direction, meaning the items only go from the roots to the leaves. But, there are other tubes that are alive, phloem. Those tubes move more complex nutrients, such as sugars. As a live tissue, the tubes need a helper to load things in. Companion cells are attached to the tube and help move the items for long-distance transport. You can also think of them as loading cells.
“It was exciting because it was something, in a way, unexpected, but at the same time needed. We were hitting the wall so many times, and we think we now know why. This is getting us closer to the answer we’ve been after. It’s exciting, too, because I was mainly interested in how nutrients move. I wasn’t after the sensing part of the equation. It was a happy accident. This protein that we characterized in another project turned out to be part of the sensing mechanism. Once you start digging, you can’t stop.”
Mendoza-Cozatl is working with Scott Peck and Dmitri A. Nusinow on the recently-funded grant from NSF. The awarded amount is nearly $1 million. Peck is a professor of Biochemistry at MU. Nusinow is an assistant member and principal investigator at the Danforth Center. Mendoza-Cozatl is the principal investigator on the grant. Peck and Nusinow are co-principal investigators.
Mendoza-Cozatl and Nusinow know each other from their work as post-docs at the University of California, San Diego.
“It’s critical on a project like this to have a strong team,” Mendoza-Cozatl said. “I could have taken on the entire project in my lab and maybe had an answer in 10 years. Partnering with Scott and Dmitri brings more power to the equation. It’s a competitive field and speed is important. I’m not the only one who wants to know how iron is sensed. Thankfully, our team is incredibly strong.”
The goal of the research is to identify the mechanisms responsible for iron sensing and homeostasis in plants. It’s vitally important that plants be able to sense the amount of iron and regulate it, mainly to avoid overload and cell damage.
“We know the main sensing takes place in the leaves, and we know the veins are where the magic happens,” Mendoza-Cozatl said. “We’re now looking at where it happens at the mechanistic level. The uptake of iron has to be regulated. Plants can turn it on when they need iron and shut it down when they have enough. We’re looking at the sensing mechanism that is key in all of this.
“We don’t know for sure which proteins make the process happen. The little plant that we work with has 25,000 parts. We don’t know the function of 50 percent of them. We are focused on finding the parts that are important for nutrient uptake and sensing.”
The research has a human health component as well. Iron deficiency in humans affects nearly 2.2 billion people, according to the World Health Organization.
“If we understand how plants handle iron, we can help make crops more nutritious,” Mendoza-Cozatl said. “We can make new lines that could handle excess iron or a smaller amount of iron. This information will help us make plants better for humans.”
Mendoza-Cozatl added that the project will provide training to undergraduate and graduate students on cutting-edge molecular biology techniques and emphasizes collaborative work between students from different disciplines, including computer sciences, biochemistry and plant sciences.
“It just makes sense to partner with the Danforth Center,” Mendoza-Cozatl said. “We both have great expertise, and it just makes sense to work together. It benefits everyone.”
Engineering Seed Oil Content
Plant oils serve as a renewable source of food, fuels and chemicals – and output of plant oils must double by 2030 to meet projected demand. A good portion of plant oils come from the seeds. Past research has led to improvements in seed oil quality and quantity – but that improvement has led to other issues. Oftentimes, plants bred to produce high seed oil have decreased protein content or make fewer seeds.
“Breeders have known for the better part of 50 years that when you try to increase oil, you get a tradeoff of lower protein, and vice versa,” said Jay Thelen, a professor of Biochemistry at MU. “No one really knows what the reason is behind this inverse relationship.
“Plant oils are integrated into the fabric of our daily lives, and we just assume that there is going to be this limitless pot of oil that we can pull from. With the amount of arable land decreasing and the population increasing, it’s critical that we find new ways to make or enhance the production of plant oils.”
Thelen is serving as the principal investigator on a $3.5 million NSF grant focused on researching the metabolic consequences arising in plants engineered to make higher seed oil, including that pesky inverse correlation.
“We’re looking at where that branch point is between protein and oil,” Thelen said. “We want to be able to increase the oil without compromising protein and vice versa. We’re hopeful that we can find scenarios where we can increase the oil and increase the protein.”
Thelen is working with four co-principal investigators on the grant: Dong Xu, professor of Computer Science at MU; Douglas Allen, USDA-ARS scientist and associate member at the Danforth Center; Abraham Koo, associate professor of Biochemistry at MU; and Philip Bates, assistant professor, Institute of Biological Chemistry, Washington State University.
“The assembled team really allowed us to take the grant to the next level,” Thelen said. “While we’re a skeptical group of biochemists, we’re optimistic about this research. That excitement came through in our writing for the grant.”
While protein has typically driven the price at market of plant seeds, the demand for oil continues to be on the rise.
“Reduced carbon is the most efficient form of energy on the planet,” Thelen said. “Plant oils represent the most reduced type of energy that one can make. The physical and chemical properties make those oils advantageous for feedstocks in the chemical industry including lubricants, nylons and cosmetics. Vegetable oils, of course, represent a big part of our diet as well and also represent a large source of renewable energy for the transportation industry.”
Thelen said that plant oils are packaged as a chemical structure called triacylglycerol, three fatty acid chains bound to a molecule of glycerol. While it looks simple chemically, Thelen said there are numerous metabolic pathways involved. There is an enzyme that sits at the top of the pathway for fatty acid biosynthesis. Carbon that goes through this pathway must first go through this enzyme.
“You can deregulate that enzyme, cut the brake lines so to speak, so that it can only accelerate,” Thelen said. “You can also put a little more weight on the accelerator. We did both. We learned that with both approaches we saw the same effect, which was higher seed oil. That suggests that we hit an important enzyme in the pathway to make fatty acids for triacylglycerol. There are obviously more steps, but it gave us a lot of confidence.”
Thelen’s lab discovered this new approach to engineer key metabolic steps in this pathway. He was able to then leverage the findings, in a biotechnological manner, to increase seed oil.
“We hope that if we spend more time with this enzyme that we can find more ways to engineer it,” Thelen said. “The goal down the line would be custom-tailored crops, where you could design crops with 50 percent oil, for example, or 10 percent oil with a bigger focus on protein. If we can understand this enzyme better, we can become better engineers of it.”
Allen’s USDA lab at the Danforth Center explores oilseeds that can provide the oil to replace some of our non-renewable dependencies. His research and background were a perfect fit for the grant.
“Doug brings a unique skillset to this problem,” Thelen said. “He’s been a great colleague and friend for a long time. We’ve worked together on projects in the past, and I’m excited to work with him on this grant. I think this is a model example of how MU and the Danforth Center work together to tackle fundamental, intractable problems in plant biology. I know there are going to be plenty of collaborations and opportunities in the future.”