Plant & Animal Genomes XIV Conference Plant & Animal Genomes XIV ConferenceJanuary 14-18, 2006
Town & Country Convention Center
San Diego, CA
Georgia Davis , Michael Gerau , Douglas Davis , Ryan Dierking , Courtney Morriss , Theresa Musket
Roots are the first plant organ to sense soil moisture deficits. Their response significantly influences the plant’s ability to survive under conditions where water is limiting. Identification of maize genes that affect root architecture and influence drought response is essential for development of drought tolerant maize. The Intermated B73 X Mo17 mapping population was used as a first step in identifying maize root architecture genes. Young maize plants were evaluated for primary root length, overall root branching, number of primary branches, and root mass. Traits were evaluated under well-watered and water-stressed conditions as measured by soil moisture and leaf relative water content and data were standardized for developmental differences based on leaf number. Thirty-seven QTL were identified. Numerous studies have demonstrated the link between abscisic acid level and drought response. Six maize abscisic acid biosynthesis genes map to the location of the drought associated root architecture QTL. Independent studies with these mutants confirm that they have altered root architecture under water stress. In a second study, brace root number, position and angle were measured on mature plants of the same population. Brace roots form the bulk of the root system in adult plants. Studies suggest that brace root angle may be predictive of drought response. Eighteen QTL were identified on chromosomes 1, 2, 5, 7, 8, 9, and 10. Several of these QTL coincide with genes that regulate epidermal cell identity or cell fate. Studies are underway to test the effect of these mutations on brace root development.