Transcriptomic analysis of starch accumulation patterns in different glutinous sorghum seeds

Sorghum is a high-quality raw material for brewing white wine, and the starch content in seeds has a large impact on brewing quality. Transcriptomic data obtained from a glutinous variety (Liaonian3) and a non-glutinous variety (Liaoza10) at 3, 18, and 30 days after pollination were analyzed to identify genes associated with starch accumulation. The amylopectin content was significantly higher in Liaonian3 compared to Liaoza10, but the amylose content and total starch content were lower. There were 6634 differentially expressed genes found in Liaoza10 between 3 and 18 d after pollination, and 779 differentially expressed genes between 18 and 30 d after pollination. In Liaonian3, there were 6768 differentially expressed genes between 3 and 18 d after pollination, and 7630 differentially expressed genes between 18 and 30 d after pollination. Genes were grouped by expression profiles over the three time points and the profiles were analyzed for enrichment of gene ontology terms and biochemical pathways. Profile 1 (decreasing expression from 3 to 30 d) for Liaoza10 was enriched in ribosomes, metabolic pathways, and carbon metabolic pathways. Profile 0 (decreasing expression from 3 to 18 d and consistent expression from 18 to 30 d) was enriched in pathways related to sugar or starch metabolism. Although the starch accumulation rate in Liaonian3 and Liaoza10 showed a profile of increasing and then decreasing, the expression of genes related to starch synthesis gradually decreased with time since pollination, demonstrating the complexity of starch synthesis. According to orthologous gene alignment and expression analysis, 19 genes such as entrzID_8068390 and entrzID_8066807 were found to be the key genes for starch synthesis and glutinous and non-glutinous differentiation in sorghum grains.