Deciphering genetic architecture and regulatory mechanism underlying the accumulation of seed storage proteins in wheat

Wheat seed storage proteins (SSPs) are an important source of nutrients and also greatly affect human health. SSPs form a polymer complex conferring wheat dough elasticity and extensibility, and their variations in components and abundance determine processing quality. Therefore, deciphering the genetic machinery and regulatory mechanism underlying SSP variation will facilitate wheat quality improvement. Development and application of efficient genome assembly, genotyping, transformation and multi-omics technologies in wheat during recent decades, greatly accelerates research progress in this field. Here, we performed a comprehensive characterization of the genetic architecture underpinning SSP accumulation and identified major genetic clusters by genome-wide meta-analysis of SSP genes and modulators as well as loci for grain protein content and processing quality traits. SSP modulators from different regulatory hierarchies were further elaborated. Considering that the highly active endosperm-specific expression of SSP genes is mainly controlled at the transcriptional level, we constructed a regulatory network by integrating trans-acting regulators, cis-acting elements and chromatin modifiers. Research strategies to mine SSP modulators and future perspectives on major challenges and research orientations were also proposed. Overall, this review delineates the molecular regulatory mechanism underlying SSP accumulation and specifies genetic resources contributing to wheat quality.