PAG-IV Plant Genome IV Conference

Town & Country Conference Center, San Diego, CA, January, 1995.

W38
Molecular Mapping of Drought Resistance Genes in Grain Sorghum

WENWEI XU(1), Oswald Crasta(1), Darrell Rosenow(2), John Mullet(3) and Henry Nguyen(1)
1. Department of Plant and Soil Science, Mail Stop 2122, Texas Tech University, Lubbock, TX 79409, USA
2. Texas A&M University, TAES, Route 3, Box 219, Lubbock, TX, 79401 USA
3. Crop Biotechnology, Texas A&M University, College Station, TX, 77843 USA

Drought is a major limiting factor for sorghum production. Stay green is an important trait associated with the post- flowering drought resistance in grain sorghum. Under the post-flowering water deficit stress, stay green trait delays the rapid premature death of leaves and plants, reduces the incidence of stalk lodging and incidence of charcoal rot disease, and helps normal grain filling. Objectives ofthis study were to identify QTLs associated with the stay green trait and to study the effect of genetic background on the QTL tagging. The F7 recombinant inbred lines (RILs) from B35 x Tx7000 and B35 x Tx430 were genotyped with RFLP markers and evaluated for their drought resistance in the replicated field trials at three locations of West Texas for two years. B35 is a stay green line,Tx7000 and Tx430 are non-stay green lines. The current RFLP linkage maps of the RIL populations have over 150 loci.Three major chromosomal regions have been found to control the stay green trait consistently in different environments and together explained about 50% of the pheno- typic variation. The chromosomal region of linkage group 3 alone accounted for up to 36% of the phenotypic variation. The genetic background did not affect the expression of major QTLs for stay green trait in both populations.
(This project is supported by USDA-NRI Grant No. 9300872.)

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