Physiological Genomics of Maize Nodal Root Growth under Drought

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PI: Robert E. Sharp (University of Missouri)CoPIs: David M. Braun, Felix B. Fritschi, Trupti Joshi, Scott C. Peck, Jonathan T. Stemmle (University of Missouri) and Melvin J. Oliver (USDA-ARS/University of Missouri) Developing drought-tolerant corn varieties that make efficient use of available water is vital to sustain the estimated 9 billion global population by 2050. Corn takes up most of its water through a particular set of roots called the nodal roots. Under drought, the nodal roots must grow through dry soil to reach available water to sustain the plant. However, very little is known about the mechanisms that allow nodal roots to achieve this essential feat. This project will use a combination of physiological and genomics approaches to define the molecular mechanisms underlying how the nodal roots are able to maintain growth under drought. The information generated by the project will lead to the development of innovative approaches to enable corn and other cereal crops to access more water and increase yield under drought, and will thereby contribute to the essential goals of increased food security and stability. In addition to the training of students and postdoctoral associates, the project will provide summer research training internships for undergraduate students from Fort Valley State University, a Historically Black University (HBCU) located in Fort Valley (GA). The project will also disseminate research findings and provide information to the general public through various communication, technical training and outreach activities. These include but are not limited to science communication workshops involving journalism students and hands-on training workshops on metabolomics and the use of bioinformatics tools to analyze and integrate multi-omics datasets. This project integrates root physiology and functional genomics [transcriptomics, plasma membrane proteomics, and metabolomics (including hormones)] to deliver a comprehensive understanding of nodal root growth responses to water deficit stress in both controlled laboratory studies and in the field. The project focuses on a maize inbred line that has been shown to exhibit superior ability for nodal root growth under water-limited conditions. A collaborative interdisciplinary team will address the following specific objectives: 1) elucidation of the physiological and molecular basis of nodal root growth responses to water stress using a novel divided-chamber model system for precise imposition of water deficit conditions around the growing roots; 2) characterization of nodal root growth and root growth zone transcriptomic responses in response to water stress in the field, using "drought simulators" for precise imposition of the timing, intensity and duration of drought; and 3) integration and analysis of all datasets using a suite of informatics tools to identify candidate genes that will be genetically validated in plants. This multidisciplinary strategy provides unique opportunities to greatly improve basic understanding of root biology under drought, and to broadly train the next generation of plant scientists. Data and biological materials generated by this project will be accessible to a project website (to be developed) and through deposition to long-term repositories such as the Maize Genetics Cooperative (for germplasm), and MaizeGDB, Gramene and the NCBI's GEO and SRA (for sequence and phenotypic datasets).