Genetic Analysis, Transcriptome Analysis, and Candidate Major Genes Screening of Peduncle Length Trait in Brewing Sorghum [Sorghum bicolor (L.) Moench]

Objectives: Peduncle length (PL) is a critical agronomic trait in sorghum [Sorghum bicolor (L.) Moench], influencing mechanical harvesting efficiency. Exploration of the PL genetic mechanism and the PL major genes of sorghum can provide a reference for breeding of sorghum suitable for mechanization and PL genetic research of other graminaceous crops. Methods: Here, we conducted genetic analysis, transcriptome analysis, and candidate major gene screening of PL using long-peduncle (KY133B) and short-peduncle (KY123B) parents, as well as their constructed F2 segregated populations. Results: Genetic analysis revealed that PL trait may be controlled by two major genes with additive-dominant effects, showing a heritability of 69.638%. At the early stage of sorghum peduncle elongation, the young panicle of the parents was sampled and performed transcriptome analysis. DEGs 3603 genes were obtained. With the short peduncle parent (F) as the control, 2204 upregulated genes and 1399 downregulated genes were expressed in the long peduncle parent (M). We compared the 1161 genes obtained by BSA-seq from the laboratory in the early stage with the DEGs obtained by RNA-seq, and obtained 148 co-localized genes. Through the high DEGs screening criteria (|Log2FC(M/F)| ≥ 5, p < 0.0001), we further identified 36 genes with highly significant expression differences between parents. Functional annotation identified four candidate major genes strongly associated with PL: LOC8056900 (MIZU-KUSSEI 1), LOC8065075 (ethylene-responsive transcription factor WIN1), LOC8083493 (GDSL esterase/lipase), and LOC8085367 (auxin-responsive protein IAA21). qPCR validated their expression trends, corroborating RNA-seq results. Conclusions: The comprehensive information presented here provides a reference for understanding the PL mechanism of sorghum and provides some important candidate major genes related to PL. This study laid the foundation for subsequent gene functional verification and mechanism analysis of sorghum peduncle length major genes.