QTL mapping and candidate genes prediction for plant height and brix content in sorghum [Sorghum bicolor (L.) Moench]

By constructing a high-density genetic linkage map using a recombinant inbred line (RIL) population from two sorghum lines with distinct variations in plant height and brix content, eight genetic loci were identified, and candidate genes associated with these traits were predicted. Sorghum, recognized as a crucial forage and energy crop, exhibits yield and quality influenced by plant height and sugar content traits. Considering the complex genetic architecture of plant height and sugar content, this study utilized a sorghum recombinant inbred line population comprising 250 lines to elucidate the phenotypic variation and genetic foundations of these traits. Utilizing streamlined genome sequencing technology, the genotypes of each line were scrutinized, culminating in the construction of a sorghum genetic linkage map spanning 1129.97 centi-Morgans (cM) and encompassing 2101 bin markers. This population was planted in Liaoning during the growing seasons from 2014 to 2020, and the phenotypes of plant height and brix content were characterized across six different environments. Simultaneously, optimal genetic models for sorghum plant height and brix content were analyzed. Eight QTLs significantly associated with plant height and brix content were identified on chromosomes 1, 5, 6, 7, and 8, using QTL mapping. In this study, two QTLs associated with plant height and one QTL associated with brix content were identified across at least two different environments. The confidence intervals of the identified major effect QTL loci were utilized to predict candidate genes. Sobic.007G163200.1 was identified as a significant candidate gene for plant height, involved in tryptophan metabolism. Two genes associated with ABC transporter-related pathways were also identified as significant candidate genes for plant height. Furthermore, three genes involved in carbon fixation in photosynthetic organisms were identified as significant candidate genes for brix content.