GhUGT84A1 underlying a novel locus qOC-A03-1 regulates cottonseed oil content revealed by integrated deep...

High-density linkage analysis using deep resequencing mapped a stable cottonseed oil content QTL qOC-A03-1, leading to the identification of UDP-glycosyltransferase gene GhUGT84A1 as a key regulator of cottonseed oil accumulation via fine mapping. As the main by-products of cottonseed, cottonseed oil and protein have great potential in economic value and edible applications. In this study, a high-density genetic linkage map was constructed with 3478 bin markers via deep resequencing method (14.11 ×) using a recombinant inbred line population. Among the 16 detected quantitative trait loci (QTLs) associated with cottonseed oil content (OC) and protein content (PC) in four environments, we focused on a stable novel QTL qOC-A03-1 responding for both OC and PC traits simultaneously and narrowed down its interval to 190 kb containing 19 genes, subsequently. Based on RNA-seq data of ovules at different developmental stages and other tissues, a UDP-glycosyltransferase gene, GhUGT84A1, showing significant differential expression during the rapid oil accumulation stage and exhibiting three non-synonymous SNPs and a 2-bp deletion causing premature translation termination in ND601 was identified. Heterologous expression in yeast confirmed that overexpression of GhUGT84A1^ND601 could significantly increase the triacylglycerol content. Interestingly, when changing the T^ND601 to A^NDM13 genotype at the 1357^th position of GhUGT84A1^ND601, the triacylglycerol content further increases. However, a 17.83%-33.55% increase in OC was detected in the silenced GhUGT84A1 cotton leaves, and the expression of genes related to fatty acid biosynthesis and metabolic pathways showed significant changes. Our investigations found that GhUGT84A1 might as a negative regulator fine-tune the cottonseed oil accumulation and could provide fundamental insights for comprehensive cotton valorization.