Unveiling new insights into integrated effects on in vitro digestibility and fine molecular structure of wheat starch...

The impact of sowing date on wheat starch digestibility remains incompletely understood, particularly regarding its fine molecular architecture (chain-length distribution and molecular weight) and the transcriptional regulation of starch synthase genes. This study systematically examined the effects of normal and delayed sowing on starch digestibility, granule morphology, chain-length distribution, crystalline structure, molecular weight, expression of eight key starch synthase genes, and functional characteristics. Delayed sowing elicited cultivar-specific alterations in gene expression, suppressing short amylopectin chains and long amylose chains while promoting long amylopectin chains, thereby increasing overall molecular weight. These structural modifications enhanced crystallinity and compacted the amorphous zone. All four wheat cultivars maintained yield while improving starch quality under delayed sowing. These results provide a mechanistic framework for optimizing showing schedules to enhance starch functionality under climate change.