Impact of TaFtsZ2 overexpression and mutation on wheat starch granule characteristics and quality

Starch granule size is strongly related to the physicochemical properties and quality of starch. This study used genetic engineering techniques to obtain mutants and overexpressing lines of the wheat amyloplast-division gene TaFtsZ2, to regulate the size and physicochemical properties of wheat starch granules. The results showed that the gene TaFtsZ2 was localized to the chloroplasts of wheat leaves. Although mutation of this gene did not result in unfavorable agronomic traits, it caused abnormal amyloplast division, leading to irregular starch morphology and increased granule size and number of micropores. Simultaneously, the mutation also led to a down-regulation in the expression of sucrose metabolism-related genes and starch-branching enzyme genes. As a result, the total starch content, amylopectin content, starch branching degree, and crystallinity all decreased compared with those of the non-mutated lines, and the contents of amylose, resistant starch, and proteins increased. The starch also exhibited lower peak viscosity and a higher gelatinization temperature. In contrast, overexpression of TaFtsZ2 promoted amyloplast division, increasing the number of small starch granules. It also up-regulated the expression of genes related to starch and sucrose metabolism, leading to an increase in starch-branching degree, amylopectin content, peak viscosity and a decrease in gelatinization temperature, ultimately improving the quality of wheat starch. This study will provide a new method for regulating the size and physicochemical properties of wheat starch granules by controlling amyloplast division and novel germplasm resources for the production of wheat starch with specific functions.