Confirmation of the location and the effects of a major QTL controlling pod dehiscence, qPDH1, in soybean

Pod dehiscence (shattering) is a major source of yield loss in mechanical harvest of soybean. To develop a marker-assisted selection system for a major quantitative trait locus (QTL) controlling pod dehiscence, designated as qPDH1, we confirmed the usefulness of flanking markers and the effect of qPDH1 under different genetic backgrounds. The progeny of a residual heterozygous line for the genomic region around qPDH1 was screened for four flanking markers to obtain various recombinants in the vicinity of the QTL. The analysis of the relationship between the pod dehiscence degree and the graphical genotype of these lines confirmed the presence of qPDH1 in the region between the SSR markers, Sat_366 and Sat_093, on linkage group J. At these marker loci, the alleles from a Thai cultivar, SJ2, the donor of the shattering resistance, were inherited by most of the shattering-resistant, SJ2-derived cultivars and were distinct from those of the shattering-susceptible cultivars tested. The effect of the allele from SJ2 at qPDH1 was confirmed by association tests under four genetic backgrounds derived from crosses with three susceptible cultivars in the northern to southwestern regions of Japan and a susceptible accession of Indonesian origin at three locations. These results suggest that the allele from SJ2 at qPDH1 and the linked markers could be widely used for the improvement of the shattering resistance in soybean.