Positional mapping and identification of novel quantitative trait locus responsible for UV-B radiation tolerance in soybean [Glycine max (L.) Merr.]

The amount of ultraviolet-B radiation (UV-B: 280–320 nm) reaching Earth’s surface is expected to increase due to stratospheric ozone depletion. This could cause significant biological damage in plants, and serious yield losses in crops. Soybean [Glycine max (L.) Merr.], a major legume crop, is known to be sensitive to UV-B radiation. Thus, developing a UV-B-tolerant soybean is an efficient and economical strategy to avoid putative yield losses through increased UV-B irradiation. The objective of this study is to identify the novel quantitative trait loci (QTLs) for UV-B tolerance in the soybean using high-density genetic linkage mapping. One hundred and fifteen F8-derived F12 recombinant inbred lines developed from a cross between the UV-B susceptible cultivar, Keunol, and a tolerant breeding line, Iksan 10, were used. Three categories of phenotypic traits were scored: degree of leaf color change, degree of leaf shape change and degree of total plant damage. A genome-wide molecular genetic linkage map containing 8691 single nucleotide polymorphism markers was constructed using the recently developed genotyping platform, the 180K Axiom SoyaSNP assay. Using composite interval mapping analysis, one major candidate QTL on chromosome 7 was identified and designated qUVBT1, and is located between two flanking makers, AX-90437826 and AX-90317546, within 1.6 cM, corresponding to a ~24-kb physical region with six annotated gene models. One of them is a homolog of yeast RAD23, which has previously been reported to be a UV excision repair protein. This result could be valuable in breeding new UV-B-tolerant soybean cultivars and elucidating the UV-B response mechanism in soybean plants.