IDENTIFICATION OF QUANTITATIVE TRAIT LOCI FOR PLANT HEIGHT, LODGING, AND MATURITY IN A SOYBEAN POPULATION SEGREGATING FOR GROWTH HABIT

The use of molecular markers to identify quantitative trait loci (QTLs ) has the potential to enhance the efficiency of trait selection in pl ant breeding. The purpose of the present study was to identify additio nal QTLs for plant height, lodging, and maturity in a soybean, Glycine max (L.) Merr., population segregating for growth habit. In this stud y, 153 restriction fragment length polymorphisms (RFLP) and one morpho logical marker (Dt1) were used to identify QTLs associated with plant height, lodging, and maturity in III F-2-derived lines from a cross of PI 97100 and 'Coker 237'. The F-2-derived lines and two parents were grown at Athens, Ga., and Blackville, S.C., in 1994 and evaluated for phenotypic traits. The genetic linkage map of these 143 loci covered a bout 1600 cM and converged into 23 linkage groups. Eleven markers rema ined unlinked. Using interval-mapping analysis for linked markers and single-factor analysis of variance (ANOVA), loci were rested for assoc iation with phenotypic data taken at each location as well as mean val ues over the two locations. In the combined analysis over locations, t he major locus associated with plant height was identified as Drl on l inkage group (LG) L. The Drl locus was also associated with lodging. T his locus explained 67.7% of the total variation for plant height, and 56.4% for lodging. In addition, two QTLs for plant height (K007 on LG H and A516b on LG N) and one QTL for lodging (cr517 on LG J) were ide ntified. For maturity, two independent QTLs were identified in interva ls between R051 and N100, and between B032 and CpTI, on LG K. These QT Ls explained 31.2% and 26.2% of the total variation for maturity, resp ectively. The same QTLs were identified for all traits at each locatio n. This consistency of QTLs may be related to a few QTLs with large ef fects conditioning plant height, lodging, and maturity in this populat ion.