LAUSR

BACKGROUND Drought stress (DS) is the main abiotic stress that maize suffered during its whole growth period, and maize is also sensitive to DS. It had been demonstrated that DS could improve the quality of normal maize starch. However, waxy maize that has special properties has not been explored in depth, which limits the breeding and cultivation of waxy maize varieties and the application of waxy maize starch. Therefore, in this study, we investigated the effects of DS on the biosynthesis, structure and functionality of waxy maize starch. RESULTS The results showed that DS decreased the expression level of SSIIb, SSIIIa, GBSSIIa, SBEI, SBEIIb, ISAII and PUL, whereas increased the SSI and SBEIIa. DS did not change the average chain length of amylopectin, while increased the relative content of fa chains (RCfa ) and decreased the RCfb1 and RCfb3 . Furthermore, DS decreased the amylose content, amorphous lamellar distance (da ), semi-crystalline repeat distance and average particle size, whereas increased the relative crystallinity, crystalline distance (dc ), the content of rapidly digested starch (RDS) in uncooked system and resistant starch (RS) content in both uncooked and cooked system. CONCLISIONS For waxy maize, DS could raise the relative expression level of SSI and SBEIIa, thus increasing RCfa . The larger number of RCfa could create steric hindrance, which can lead to producing more RS in waxy maize starch. This article is protected by copyright. All rights reserved.