A genetic model and molecular markers for wild oat (Avena fatua L.) seed dormancy

Seed dormancy allows weed seeds to persist in agricultural soils. Wild oat (Avena fatua L.) is a major weed of cereal grains and expresses a range of seed dormancy phenotypes. Genetic analysis of wild oat dormancy has been co mplicated by the difficulty of phenotypic classification in segregating pop ulations. Therefore, little is known about the nature of the genes that reg ulate dormancy in wild oat. The objectives of our studies were to develop m ethods to classify the germination responses of segregating wild oat popula tions and to find molecular markers linked to quantitative trait loci (QTL) that regulate seed dormancy in wild oat. RAPD markers OPX-06 and OPT-04 ex plained 12.6% and 6.8% respectively, of the F-2 phenotypic variance. OPF-17 was not significant in a simple regression model, but it was linked in rep ulsion to OPT-04. A three-locus model of seed dormancy in wild oat is prese nted based on the 41-day germination profiles of F-1, F-2, F-3, BC1P1F1, BC 1P1F2, and BC1P2F1 generations, and the 113 day germination profile of 126 F-7 recombinant inbred lines. Loci G(1) and G(2) promote early germination, and the D locus promotes late germination. If at least one copy of the dom inant G(1) or G(2) alleles are present regardless of the genotype at D locu s, then the individual will be nondormant. If the genotype is g(1)g(1)g(2)g (2)D_, then the phenotype will be dormant.