玉米盾片发育过程中超微结构的变化

玉米授粉后10天,盾片处于组织分化期,细胞中已有少量脂体和淀粉粒,上皮细胞的细胞质明显浓于其内部的薄壁细胞,线粒体、质体、核糖体也较薄壁细胞中多。授粉后20天,盾片细胞中液泡消失,形成了大量脂体和淀粉粒,上皮细胞与胚乳相邻的壁及径向壁外段次生加厚,具内部的薄壁细胞中自上而下开始形成蛋白质体。授粉后35天,上皮细胞发育成径向略长的形状,径向壁加厚达细胞的2/3处,仍呈薄壁状态的壁处有发达的胞间连丝;其内部的薄壁细胞中形成了许多蛋白质体。成熟籽粒的盾片中,上皮细胞的细胞核明显,其径向壁的内段仍保持薄壁状态,外段的加厚壁有波状内突,胞质中含有大量脂体和少数淀粉粒,无蛋白质体但有许多蛋白质基质;上皮细胞以内的薄壁细胞中有大量球形蛋白质体、脂体和较多淀粉粒,脂体有规律地排列在蛋白质体周围。盾片发育后期,淀粉粒逐渐减少,蛋白质体增多。

Ultrastructure Changes during Scutellar Development in Maize (Zea may L. )

The maize scutellar cells started differentiation at 10 days after pollination (DAP), and a few lipid bodies and starch grains were found. The cytoplasm was more dense and more mitochondria, plastids and free ribosomes were found in epithelium than in parenchyma of scutellar. By 20 DAP, vacuoles disintegrated, many lipid bodies and starch grains formed. The outer wall and the outer parts of in radial wall thickened in epithelium, and protein bodies started to form from upper cells to basal cells in parenchyma. By 35 DAP, the epithelium developed to longer in cell redial, the radial cell walls thickened to take about 2/3 of these cells. The plasmod-esmata presented on the thin walls of these cells. The numerous protein bodies were formed in parenchyma cells. There were more clear nucleus, numerous lipid bodies and fewer starch grains, no protein bodies but protein radical were found in the epithelium of mature scutellar. The inner parts of radial wall in epithelium were still thin, and the thickened walls formed wavy ingrowths. But there were a great number of protein bodies, lipid bodies and many starch grains, in the parenchyma of scutellar, lipid bodies arranged regularly around protein bodies. The number of protein body was increasing with reducing of starch grains in scutellar development late stage.