Monday, November 5, 2007
81-10
Identification of Quantitative Trait Loci for Delayed Wilting in Soybean.
Dirk Charlson1, Sandeep Bhatnagar2, C. Andy King1, Larry Purcell1, Jeffery Ray3, Clay Sneller4, and Tommy E. Carter5. (1) Crop, Soil, and Environmental Sciences, University of Arkansas, 1366 W. Altheimer Drive, Fayetteville, AR 72704, (2) Monsanto Company, 995 US Highway 19 N, Leesburg, GA 31763, (3) USDA-ARS, 141 Experiment Station Rd., Stoneville, MS 38776, (4) Horticulture & Crop Science, Ohio State University-OARDC, 1680 Madison Ave., Wooster, OH 44691, (5) Crop Science, North Carolina State University, 4411 Williams Hall, Campus Box 7620, Raleigh, NC 27605
Water availability is a limiting factor for soybean production and yield in areas of the United States prone to drought. An important aim of breeding efforts is identification of genes controlling traits, such as delayed canopy wilting, that maintain yield potential during water-deficit stress. Wilting is a quantitatively inherited trait and very little has been reported on the genetic mechanism of delayed wilting in soybean. Our objective was to examine the inheritance of delayed wilting using quantitative trait loci (QTL) analysis. Delayed wilting was examined in a recombinant inbred line (RIL) population of F5-dervied lines developed from the cross between KS4895 and Jackson. Wilting scores were collected on a scale of 1 (no wilting) to 5 (severe wilting). A randomized complete block design was used at each of three environments with three replications. Data were collected during water-deficit stress from the parents and 80 RILs at Arkansas in 2000 and 2003, and North Carolina in 2002. Although, the parents did not differ significantly in their wilting response to drought, transgressive segregation was observed in the RIL population. Therefore, a genetic map was developed for the population using 160 simple sequence repeats markers genetically spaced approximately 20 cM across all 20 molecular linkage groups (MLG). By associating the delayed wilting trait with the molecular markers, we have identified three QTLs for delayed wilting associated with MLGs A1, F, and K. Our preliminary findings suggest that several genes may be involved in the expression of delayed canopy wilting in soybean.