Trehalose-6-phosphate phosphatase-mediated trehalose metabolism shapes sorghum grain domestication for brewing adaptation.

Grain length-to-width ratio (GLWR) is a crucial trait influencing sorghum grain quality, particularly in brewing applications such as Baijiu production. However, the genetic basis of GLWR remains poorly understood. Here, we performed a genome-wide association study (GWAS) on 255 Chinese sorghum accessions and identified a gene, encoding trehalose-6-phosphate phosphatase, named SbTPP1, as a principal modulator of GLWR. Population structure analysis revealed three distinct subgroups, with Chishui subgroup exhibiting the roundest grains. SbTPP1, located on chromosome 7, contains 2 InDels and 5 SNPs in the coding sequence that differentiate long-grain and round-grain alleles, which shows strong selection signatures in Chishui germplasm and higher expression in round-grain accessions. Overexpression of SbTPP1 in transgenic sorghum significantly increased GLWR but reduced thousand grain weight. Haplotype analysis of 737 global sorghum accessions traced the round-grain allele (Hap1 and Hap3) to African origins, while the long-grain allele (Hap2) arose during sorghum's migration to China. This study establishes SbTPP1 as a candidate gene controlling GLWR underlying grain shape variation and population-specific selection in Chinese sorghum, via the trehalose metabolism pathway. These insights provide molecular insights into sorghum grain shape determination and offer valuable genetic markers for breeding programs aimed at optimizing grain morphology for industrial uses.