Abstract
Heat stress during early ripening period cause abnormal maturing of seeds such as milky white kernels in rice. The aim of this study is to elucidate its mechanism. We harvested immature rice seeds with or without high temperature stress, and examined seed quality and activities of α-amylase and ADPglucose hydrolyzing enzyme NPPase that are relatively heat-stable compared with the other enzymes related to starch metabolism. Both activities were shown to increase in cultivars which exhibited poor quality of seed compared with the others. Proteome analysis showed that the expression of proteins related to glycolytic pathway, reactive oxygen species elimination, and chaperonin are affected by high temperature stress. Furthermore, we analyzed oxidation status of proteins in the immature seeds with biotinhydorazide that binds to carbonyl group of proteins, indicating that proteins oxidized under high temperature stress significantly increased in heat-susceptible cultivars.
