LIGHT AND ELECTRON-MICROSCOPIC AND ENERGY-DISPERSIVE X-RAY-MICROANALYSIS STUDIES OF GLOBOIDS IN PROTEIN BODIES OF EMBRYO TISSUES AND THE ALEURONE LAYER OF RICE (ORYZA-SATIVA L.) GRAINS

To understand the differences in mineral nutrient storage within tissu es and organs of rice (Oryza sativa L.) grains, the distribution of gl oboids in rice embryo and endosperm tissues was examined using light a nd transmission electron microscopy and energy dispersive X-ray microa nalysis was used to study globoid composition. Globoids were found in most embryo tissues, including provascular cells, and their location a nd size in sections of protein bodies is described. While P, Mg, and K were commonly detected in all globoids, other elements such as Ca, Mn , Fe, and Zn were sometimes detected in globoids of specific tissues a nd (or) regions. High peak-to-background ratios for P were obtained in globoids of scutellar and aleurone cells, and moderately high values were detected in ground meristem regions of the mesocotyl and coleopti le. Relatively high K levels were found in globoids in parenchyma cell s of the scutellum and coleorhiza; in provascular cells of the radicle ; and in ground meristem cells from the mesocotyl, coleoptile, and plu mule. Calcium was mainly detected in globoids of the aleurone layer. I ron was mostly found in radicle tissue globoids. Zinc was commonly fou nd in globoids of the scutellar epithelium and in provascular tissues of the mesocotyl, coleoptile, and radicle. Manganese was distributed t hroughout most of the tissues examined, but the highest levels of Mn w ere detected in globoids from the coleoptile tip regions and the plumu le. A novel finding was that, in the provascular tissues of the coleop tile tip, distinctive differences were found in Mn, Fe, and Zn storage between globoids in the future xylem and the future phloem.