MOLECULAR MARKERS ASSOCIATED WITH WATER-USE EFFICIENCY AND LEAF ASH IN SOYBEAN

Water use efficiency (WUE) is an important trait that has been associa ted with drought tolerance of crop plants, and leaf ash (LASH) is gene rally related to WUE, A restriction fragment length polymorphism (RFLP ) map was constructed from a soybean [Glycine max (L.) Merr.] populati on of 120 F-4-derived lines from a cross of 'Young' x PI 416937. The p urpose of this research was to identify quantitative trait loci (QTL) associated with WUE and LASH in 36-d-old, greenhouse-grown plants, The experimental design was a randomized complete block with six replicat ions. Significant (P < 0.01) phenotypic differences were detected amon g the lines for both traits, A total of four and six independent RFLP markers were associated with WUE and LASH and if combined each group o f markers would explain 38 and 53W of the variability in the respectiv e traits, One marker locus (cr497-1), on USDA Linkage Group J, explain ed 13.2% of the variation in WUE indicating the presence of a major QT L, The LASH was negatively correlated with WUE (r = -0.40*), and two QTL were associated with both WUE and LASH, For each of these QTL, the allele for increased WUE was associated with reduced LASH.