The interaction between amylose and amylopectin synthesis in rice endosperm grown at high temperature

•GBSSI is involved in amylopectin biosynthesis.•GBSSI has more effect on the synthesis of amylopectin with a DP greater than 60.•High temperature disequilibrates amylose and amylopectin synthesis.•Enzymatic experiment can verify the biological meanings of structural parameters. Starch is the abundant component in rice endosperm, and its microstructure determines the quality and functional properties of rice grain. It is well known that the starch fine structure is markedly influenced by high temperature during grain filling. However, it is poorly understood on the competition among starch synthesis related enzymes as well as the interaction between amylose and amylopectin biosynthesis under increased growing temperature. In this study, the non-waxy and waxy rice were planted under normal and high temperatures. Parameterizing analysis of the starch microstructure using mathematical models proved that amylose synthesis competed with the elongation of long amylopectin chains (DP＞60); Short chains of amylopectin can be used as the substrate for elongation of longer amylopectin chains; High temperature eliminated the consistency and regularity of the synthesis of amylose and amylopectin. In addition, enzyme assay proved the validity of fitting results from mathematical modeling analysis of starch.