Observational studies on amyloplasts with single-starch granule in rice endosperm

Abstract

Rice is one of the most important cereal crops worldwide. Grain chalkiness has been reported to decrease rice quality and to be associated with starch biosynthesis and accumulation. In order to explore mechanism of chalky starch formation, microscopic and submicroscopic techniques were adopted in this study to observe the amyloplast morphology of rice endosperm cells. These techniques used serial semi-thin sections of rice caryopsis endosperm cells and chalky rice kernels at different development stages after anthesis. Amyloplasts with single-starch granule existed in both developing and mature endosperm cells from their appearance to degradation. In addition, particle size analysis of the chalky and normal starch granules showed that the circularity of the chalky single-starch granule was greater than that of the normal starch granule. Given the loose arrangement of single-starch granule caused by undesirable development, its granule is different from that of the normal endosperm cell. Therefore, the defective development of starch might be related to the chalky formation.