Inheritance and fine mapping of a major barley seed dormancy QTL

A major barley seed dormancy locus, SD1, was previously identified along wi th three others by quantitative trait locus (QTL) analysis in a Steptoe x M orex mapping population. Located in the centromere region of barley chromos ome 7 (5H), SD1 shows the largest and most consistent effect on dormancy. S teptoe contributes the dormancy allele at SD1. The objective of this study was to determine the inheritance of and a more precise map location for SD1 . A segregating population was designed and generated by marker assisted ma ting in which only SD1 segregated. The segregation ratio suggested a single Mendelian gene in which the dormancy allele is dominant to the non-dormanc y allele at SD1. In addition, near isogenic lines (NIL) for the SD1 chromos ome region were generated by molecular marker assisted backcrossing. Statis tical analysis of germination percentages of these NIL revealed that there may be a gene cluster of at least three genes in the SD1 locus region. The dormancy locus, presumably SD1 or a part of the SD1 complex, was resolved i nto a approximate to 4.4 cM region. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.