When it came to studying the physiology and function of nodal roots of corn, Bob Sharp knew it was going to take an army. Fortunately, it did not take him very long to assemble an interdisciplinary team — six of whom are members of MU’s Interdisciplinary Plant Group (IPG) — that was up to the task of tackling a topic that has been relatively unexplored due to its complexities.
After working on the initiative for several years, this past spring marked the announcement of a four-year project being funded by a $4.2 million grant by the National Science Foundation under the name of “Physiological Genomics of Maize Nodal Root Growth under Drought” — with Sharp, director of the IPG and professor of Division of Plant Sciences, serving as the principal investigator. News of the grant was first released on March 10 when Missouri Gov. Jay Nixon visited with members of the MU plant sciences community at the Bradford Research Center in Columbia.
Out of the six co-principal investigators, three reside within the College of Agriculture, Food and Natural Resources: Felix Fritschi, associate professor in the Division of Plant Sciences; Scott Peck, professor in the Division of Biochemistry; and Melvin Oliver, adjunct professor in the Division of Plant Sciences and a supervisory research geneticist with the USDA Agricultural Research Service. “It is rare for a grant project of this scope and length to have all principal investigators on one campus,” Sharp said.
“It’s certainly unusual to have the entire team in one place, and it’s partly because this is what the IPG is all about,” Sharp said.
The other members on the multidisciplinary team are Jon Stemmle, associate professor of strategic communication at the School of Journalism; David Braun, associate professor in the Division of Biological Sciences in the College of Arts and Science; and Trupti Joshi, assistant research professor and director of translational bioinformatics in the Department of Molecular Microbiology and Immunology in the School of Medicine.
“I think we all buy into this idea that we can do something really important by working together,” Peck said.
Between now and 2020, the team will look at how corn plants maintain root growth in drought conditions by analyzing all aspects of their nodal roots, which serve as the pathways for m0st of the plant’s water uptake.
“These are important roots, and we know almost nothing about them,” Sharp said.
There have only been two previous publications on the physiology of corn nodal root growth under drought: one that Sharp co-wrote in 1979 as a doctoral student at Lancaster University in England, and one that was co-written in 1985 by John Boyer, Distinguished Research Professor in the Division of Plant Sciences, who at the time worked at the University of Illinois Urbana-Champaign (when Sharp was at Illinois as a postdoctoral fellow).
Although Sharp continued to devote his research to roots and their responses to drought, he shifted his focus away from the nodal roots to primary root of young seedlings for the past 30 years because of their suitability for lab-based studies.
“You can say this is a multidisciplinary extension of my long-term research,” Sharp said. “I decided at this stage in my career, we should now build on that foundation. For me, it’s like full circle. We can now build on this knowledge to study the more complex nodal root system.
“In the real world, it’s how nodal roots adapt to drought which is most important.”
Nodal roots, known also as “brace” or “prop” roots for helping stabilize the plant at the bottom of the stem, form the major framework of a corn plant’s mature root system. Sharp said 90 percent of that root system is dependent upon successful growth of the nodal roots, which go deep into the soil and then produce lateral roots that take up water and nutrients in the soil.
During a drought, though, it becomes imperative for the nodal roots to dive down deeper into the soil profile to find the needed water. However, soil can become so dry that it can cause nodal root growth arrest resulting in “rootless corn syndrome,” which impedes the roots from taking up water and leaves the plant susceptible to lodging (being blown over).
Fritschi, who specializes in research aimed at understanding crop responses to abiotic stress, has developed a strong interest in root architecture and growth as related to drought stress. “It is surprising, yes,” said Fritschi about the lack of research in this particular subject area. “I think it’s more about the complexity associated with studying roots, especially physiology. Morphology and architecture of the root system are a lot easier to study than the function of the roots.”
Fritschi saw the project as a means of conducting translational work that would eliminate the initial constraints of isolated laboratory and field work.
“A lot of things that are done in the lab don’t readily translate to the field, so it’s important to understand how discoveries made in the lab can be leveraged so that they can be put to use for farmers,” Fritschi said. “There are a lot of people who only work under controlled-environment conditions. It is not easy to translate findings from the lab to the field, but that’s why it’s exciting that we can have a group here where we can do that.”
In this project, the traditional roles are blurred, as plant biology and biochemistry students work with close to 3,500 plants on a 0.1-acre plot at Bradford Research Center. Fritschi oversees the field research along with Shannon King, a doctoral student in biochemistry, and Nicole Niehues, a research specialist. The operation includes two drought simulators that Fritschi and Sharp have used at the center since 2011.
In order for the project to run smoothly, the root systems of plants being grown at Bradford will continually be compared to the plants that are growing in state-of-the-art growth chambers that were installed earlier this month in Sharp’s lab.
“The whole goal of this is nobody sits in comfort,” said Peck, who specializes in the study of how plants respond to abiotic stresses like drought and heat. “We have to get past this barrier that we sort of stay in the lab and say ‘that’s probably the way it works.’”
Peck and his team have generated a multitude of data from a model plant, Arabidopsis, but said that the plant has its limitations. He welcomed an opportunity to switch his focus to a plant like corn that not only is an understudied crop plant with global implications, but also has its primary root structure well defined from a physiological standpoint by Sharp and his team.
Peck started working five years ago on protein dynamics of primary roots.
“The question now is ‘Does our knowledge of the primary root translate over to the nodal root?’” Peck said.
One of Peck’s graduate students, Xinzhou Liu, has taken water stress response data from the primary root and started building tools to further characterize the nodal roots. Peck said the goal is to be able to know exactly what happens at certain points in time. They find this by following the path of the protein and ribonucleic acid (RNA) inside the roots.
Liu’s initial findings in RNA isolation have produced a set of molecular markers, which should go a long way toward the end goal of defining all of the responses.
In order to collect the RNA from the field at Bradford, Liu and his fellow colleagues have been relying on liquid nitrogen to flash freeze the dissected roots of four-week-old plants. Once frozen, a basic mortar and pestle is used to grind the frozen sample into a powder.
From there, the sample goes into a special isolation buffer, which filters out proteins that degrade the RNA. A precipitate solution is then used to get rid of the DNA (deoxyribonucleic acid), resulting in a little white pellet at the bottom of an Eppendorf tubes that contains the sample’s RNA transcript — allowing researchers to measure RNA levels and know if it came from any particular gene that could control the plant’s ability to dig deeper into soil.
Science meets storytelling
Stemmle, who has worked on several communication projects with researchers at the Bond Life Sciences Center since arriving on campus in 2003, joined the team to include broader impacts within the grant by finding ways to make the research more accessible to the public.
The first phase happened this summer when he held a series of workshops with graduate students (working on their master’s and doctoral degrees) and postdoctoral fellows to help them become comfortable explaining the work they were doing to a lay audience — ranging from the general public to politicians to children. A group of those students, Stemmle said, practiced what they learned to all three audience types at CAFNR’s exhibit during Governor’s, Legislators’ and Judges’ Day at the Missouri State Fair on Thursday, Aug. 18.
“Normally scientists will talk about things in a very chronological manner and for a journalistic and pubic point of view, it’s ‘What’s the most important thing?’ so it’s really a paradigm shift for them in terms of how they think about their research in a way that would appeal to the public,” Stemmle said, who is the former director of the Health Communication Research Center.
This fall the program will fund three undergraduate students from the School of Journalism to work in laboratories and produce content (articles, videos, blogs, etc.). The content will appear on a website that is in the works.
In the future, the project will also provide summer research training internships for undergraduate students from Fort Valley State University, a historically African-American university located in Fort Valley, Georgia.
Engineering a solution
When it comes to the impact that drought conditions can have on the world as a whole, the narrative often implicates that profit will be lost. Peck, though, said those numbers often do not reflect how many people are farming for the sake of sustenance, not profit.
Instead, Peck said another statistic from the Food and Agriculture Organization of the United Nations best tells of the necessity of producing drought-tolerant corn and other crops: Agriculture accounts for more than 70 percent of fresh water removed from rivers and lakes. Furthermore, that number climbs to as high as 80 percent in developing countries.
“We don’t just need to produce more food,” Peck said. “We need to produce it with greater water use efficiency. We’ve got to get this number down, otherwise even if we’re trying to grow food right in those countries, there won’t be enough fresh water for the populations.”
South Africa, for instance, now experiences its worst drought in 30 years, and corn is its biggest crop. After conducting an initial symposium in June 2015 with the plant sciences community at the University of Western Cape (UWC) in Cape Town, Sharp and other members of the IPG hope to use international collaborative relationships to help tackle issue of drought and plant stress reactions.
At the recent celebration of the 30th anniversary of the partnership between MU and UWC this past May, Sharp spoke at the ceremony. His speech included an overview of the nodal root drought project. Sharp’s hope is to be able to have a UWC doctoral student come help with research for a year as part of the grant (and possibly vice versa), after initially striking up a partnership with Ndiko Ludidi, the chair of UWC’s biotechnology department a few years back.
“It’s a door not only to the UWC, but to the entire plant science community in South Africa,” Sharp said.
Fritschi said it is important to note that several cereal grain crops share a similar growth physiology with corn, including wheat, sorghum and millet. Any keys discovered in the project could unlock several doors down the road.
“This significant funding from the NSF exemplifies the excellence of CAFNR and the Interdisciplinary Plant Group and the commitment to solving hunger and providing the resources needed to sustain world growth,” CAFNR Dean Tom Payne said in a statement back in March. “We’re proud to be leading the effort and look forward to the results that will benefit the world.”
Peck added that when it comes to stress tolerance, every percent increase in the nodal roots’ ability to dig deeper equates to an improvement in overall yield under drought conditions — and possibly one day to a new line of seeds that will be genetically coded to address the rising issue of producing more food using less water.
“If we can understand the trait we’re really looking for,” he said, “not only might we be able to engineer it, but we can also help the breeders target something more rapidly.”