关键词: 水稻, 胚乳细胞, 淀粉体, 糊粉层, 糯稻, 籼稻

Abstract: 【Objective】The objective of this research is to clarify the difference of rice endosperm of different varieties during the development process.【Method】Four rice varieties, Nipponbare, Yangdao 6, Wuyunuo16 and Yangfunuo 4 were used as the experimental materials, and their caryopsis development days precisely were precisely recorded and their caryopsis development was closely observed. Starch accumulation and physiological activities were observed by I₂-KI and TTC staining. Structure changes of rice starch endosperm cells were observed by applying spur resin embedding and semi-thin sectioning, and light microscopy. The ultrastructure and element analysis of full ripe rice caryopsis were observed under scanning electron microscope and EDS. 【Result】Four stages occurred in caryopses development of all the rice varieties tested: formation stage, milky stage, dough stage, and full maturity stage. Compared to development stages of the endosperm, formation stage runs in parallel to the coenocyte and cellurization stages, which are the initial stage of endosperm formation; milky stage corresponds to the differentiation stage of endosperm cells, while the last two stages, dough and full maturity stages, are equivalent to that of the endosperm maturity stage. The shape of two rice sub subspecies, japonica and indica, varies significantly. Of the four rice varieties tested, two indica varieties showed a relatively faster growth rate than two japonica cultivars; Wuyunuo16 and Yangfunuo 4 had almost identical growth rate of dry matter accumulation. Nuclei of starch endosperm cells degenerated with the extension of amyloplasts, while amyloplasts were still enlarging and growing. Amyloplasts in the endosperm cells were compound granules, and their development pattern possibly affected a certain quality of endosperm. Amyloplast in endosperm cells was spherical or elliptic in shape during early developmental stage, but turns to polyhydric during the late development stage. Two glutinous rice cultivars tended to have a loosely stacked endosperm and as a result, caused the appearance to be less transparent. Aleurone cell volume of two indica cultivars were bigger than japonica ones, mature aleurone cells were rich in minerals like P, K, Mg, and S. Cultivar Yangfunuo 4 had some single amyloplast detected in aleurone cells and, showed a higher level of O element content.【Conclusion】The development of starchy endosperm is autonomous and is independent of the existence of endosperm nuclei. The two non-glutinous rice cultivars have a more densely packed endosperm, The types of starch contents in cells from scutellum, pericarp and endosperm are relatively distinct in two glutinous rice cultivars, which stresses the disparate set of mechanism of starch synthesis between maternal tissue, endosperm and embryo.

Key words: rice, endosperm, amyloplast, aleurone, indica, japonica