QTL Mapping and Data Mining to Identify Genes Associated with Soybean Epicotyl Length Using Cultivated Soybean and Wild Soybean

Soybean () plants first emerged in China, and they have since been established as an economically important oil crop and a major source of daily protein for individuals throughout the world. Seed emergence height is the first factor that ensures seedling adaptability to field management practices, and it is closely related to epicotyl length. In the present study, the Suinong 14 and ZYD00006 soybean lines were used as parents to construct chromosome segment substitution lines (CSSLs) for quantitative trait loci (QTL) identification. Seven QTLs were identified using two years of epicotyl length measurement data. The insertion region of the ZYD00006 fragment was identified through whole genome resequencing, with candidate gene screening and validation being performed through RNA-Seq and qPCR, and was ultimately selected as an epicotyl length-related gene. Through combined analyses of phenotypic data from the study population, expression was found to be elevated in those varieties exhibiting longer epicotyl length. Haplotype data analyses revealed that epicotyl data were consistent with haplotype typing. In summary, the QTLs found to be associated with the epicotyl length identified herein provide a valuable foundation for future molecular marker-assisted breeding efforts aimed at improving soybean emergence height in the field, with the gene serving as a regulator of epicotyl length, offering new insight into the mechanisms that govern epicotyl development.