Michael Udvardi, Ph.D.
Senior Vice President & Division Director
Problem 1: Nitrogen (N) is essential for plant growth but is present at low concentrations in most soils. Therefore, agriculture in developed countries uses enormous amounts of nitrogen fertilizer to ensure high yields, albeit at great energy, economic and environmental cost. In contrast, farmers in many developing counties lack nitrogen fertilizers to ensure high yields and food security.
Problem 2: Plant organ senescence is a controlled developmental process that enables nitrogen remobilization from dying organs to growing organs, including new roots, leaves and seeds. Although it supports reproductive success, age-related or environmentally-triggered leaf senescence reduces the nutrient content of vegetative tissues and, therefore, quality of forage biomass. Untimely senescence can also reduce total biomass production.
Problem 3: Abiotic stress, such as drought, salinity and extreme temperature, severely effect plant growth and productivity. Periodic drought is a perennial problem in the rain-fed agriculture of our region.
Approach 1: Symbiotic Nitrogen Fixation (SNF), the reduction of atmospheric dinitrogen to ammonium by bacteria within plant cells, is a natural solution to the problems of too much or too little nitrogen in rich or poor farming systems, respectively. SNF in legumes enables them to be productive without the use of nitrogen fertilizers. The Udvardi group explores the genetic and biochemical basis of SNF in legumes using the model species Medicago truncatula, a close relative of the important forage species M. sativa (alfalfa). Over the past few years, we have discovered many genes that are essential for nodule development and SNF. Nodules are specialized organs that develop from roots to accommodate nitrogen-fixing bacteria within plants cells. While we continue to discover new genes required for SNF, we are also looking to identify genes that could be used to improve SNF in legumes and to extend this important process to nonlegume plants. The ultimate objective of this research is to increase yield and quality of forage and crop plant species without the use of nitrogen fertilizers.
Approach 2: Using switchgrass as a model system, we have characterized annual shoot senescence and nitrogen remobilization in this dual-purpose forage/biomass species using a physiological approach. Parallel genomic and molecular biology approaches have uncovered gene networks and potential regulatory genes that orchestrate senescence in switchgrass. Ongoing systems biology and genome editing approaches aim to enhance yield and quality of model and forage legume and grass species by altering the activity of key regulators of senescence.
Approach 3: Natural variation exists in all plant species for tolerance to abiotic stresses, with some genotypes performing better than others under different types of stress. Plant breeders utilize natural variation in stress tolerance amongst genotypes to improve cultivars for release in specific regions, typically without knowing the mechanistic and genetic bases of stress tolerance. We are utilizing natural diversity within model and forage species together with genomic, genetic, molecular and physiological approaches to gain insight into the mechanistic and genetic bases of abiotic stress tolerance in plants. The objective is to accelerate the development of stress-tolerant cultivars for regional and national use.
- Regulation of senescence and nutrient remobilization in switchgrass
- Genetic and cellular dissection of mutualistic plant-microbe symbioses in Medicago truncatula
- Engineering synthetic symbioses between plants and bacteria to deliver nitrogen to crops
- Plant Nitrogen Network (PlaNNet); Coordinating Research on Plant Nitrogen for Sustainable and Productive Agriculture
- Genome-wide analysis of small signaling peptides in Medicago truncatula with an emphasis on macronutrient regulation of root and nodule development
- Establishment to senescence: plant-microbe and microbe-microbe interactions mediate switchgrass sustainability
- Characterization of genes with potential to improve symbiotic nitrogen fixation in legumes
- Discovery of genes and mechanisms underlying abiotic stress tolerance in plants
- Characterization of transporters involved in nutrient exchange between legumes and rhizobia during symbiotic nitrogen fixation
- Discovery and utilization of senescence regulators to improve yield and quality of forage species