Abstract
Drought is one of the abiotic stresses limiting the production of soybean (Glycine max). Elucidation of the genetic and molecular basis of the slow-wilting (SW) trait of this crop offers the prospect of its genetic improvement. A panel of 188 accessions and a set of recombinant inbred lines produced from a cross between cultivars Liaodou 14 and Liaodou 21 were used to identify quantitative-trait loci (QTL) associated with SW. Plants were genotyped by Specific-locus amplified fragment sequencing and seedling leaf wilting was assessed under three water-stress treatments. A genome-wide association study identified 26 SW-associated single-nucleotide polymorphisms (SNPs), including three located in a 248-kb linkage-disequilibrium (LD) block on chromosome 2. Linkage mapping revealed a major-effect QTL, qSW2, associated with all three treatments and adjacent to the LD block. Fine mapping in a BC2F3 population derived from a backcross between Liaodou 21 and R26 confined qSW2 to a 60-kb interval. Gene expression and sequence variation analysis identified the gene Glyma.02 g218100, encoding an auxin transcription factor, as a candidate gene for qSW2. Our results will contribute significantly to improving drought-resistant soybean cultivars by providing genetic information and resources.
