Wednesday, November 15, 2006
270-2

Targeted genomic mapping of a wheat red seed color gene using wheat ESTs and synteny with rice.

Vasu Kuraparthy, Shilpa Sood, and Bikram S. Gill. WGGRC, Department of Plant Pathology, Kansas State University, Manhattan, KS 66506-5502

Seed dormancy is either tightly linked or pleiotropically controlled by seed color in wheat because most of the red-seeded wheats are tolerant to pre-harvest sprouting in comparison to white seeded-wheats. Seed color in hexaploid wheat is controlled by dominant red seed color genes R-A1, R-B1, and R-D1 that are located in orthologous positions on chromosome arms 3AL, 3BL and 3DL, respectively. Previous mapping efforts showed that R loci were mapped in an 8-12 cM interval flanked by orthologous alleles of RFLP markers Xbcd131 and Xabc174 on chromosome arm 3L. By using wheat ESTs and synteny with rice, we identified one co-segregating STS marker and one closely linked EST marker to R-A1 in an RIL population of Langdon x Langdon (dic 3A). Physical mapping of the R-A1 gene using tightly linked markers on a set of deletion lines specific to the long arms of group-3 chromosomes indicated that the red seed color genes are located in the distal region (less than 10% of the chromosome arms 3L), which is a high-recombination, gene-rich region in wheat. A high-resolution mapping population of 1,200 F2 plants from the above mentioned cross and 450 F2 plants from a cross between Langdon x Langdon (dic 3B) is being used for fine mapping of the red seed color gene(s) in wheat.