Exploring the genetic basis of transgressive variation in rice.

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PI: Susan r. McCouch (Cornell University-State)CO-PIs: Carlos D. Bustamante (Cornell University), Georgia C. Eizenga (University of Arkansas/ARS), Anna M. McClung (Texas A&M University) Rice (Oryza sativa) is a complex species consisting of at least five, genetically distinguishable sub-populations that inhabit diverse ecological and geographic zones throughout Asia. Evidence to date suggests that these groups are indicative of general combining ability, similar to the heterotic groups of maize. This project is designed to test the hypothesis that sub-population structure in rice is predictive of transgressive variation and to begin to characterize the underlying genetic basis of this phenomenon. To do this, the Investigators will 1) document the genome-wide differences in allelic variation within and between the different subpopulations of O. sativa and O. rufipogon using a high resolution SNP assay, 2) undertake association mapping in rice using phenotypic evaluations for 26 core agronomic and grain quality traits, 3) systematically develop genetic materials that will allow us to explore the relationship between diversity and transgressive variation that occurs when subpopulations are crossed and 4) establish a dataset for rice that can be compared with that of the maize diversity project and ultimately with other cereal species. As part of a targeted educational outreach effort, the Investigators will conduct hands-on genomics exercises in local high schools, host high school and undergraduate students as summer interns with an emphasis on broadening participation of underrepresented groups, and will develop a multi-media video presentation exploring the culture of rice in America and in Africa to be shared with K-8th graders.A better understanding of the genetic basis of transgressive variation in inbred crop species will have an immediate impact on the global research agenda for crop improvement. Presently, there is a great deal of interest in breeding hybrid rice as a mechanism for delivering superior varieties to farmers. But without a sound scientific understanding of the genetic mechanisms that underlie superior performance in naturally inbreeding species, some of the most promising opportunities to capture superior performance in the world's inbred crop varieties may be overlooked. The knowledge to be gained from this project will help inform thinking about how to best characterize and manage Oryza gene pools and about the relative investments that we, as a society, choose to make in developing inbred and/or hybrid varieties of our most important food staples. The genetic stocks produced as part of the project will augment the collection available through the Genetic Stocks-Oryza (GSOR) located at the Dale Bumpers National Rice Research Center (DBNRRC) in Stuttgart, Arkansas and the National Center for Genetic Resources Preservation (NCGRP) facility in Fort Collins, CO. Information on rice diversity will be available over the project web-site, the GRIN database and will be integrated into the Gramene database (www.gramene.org).