高淀粉玉米胚乳淀粉粒度分布特征及其对水分胁迫的响应

Starch Granularity Distribution and Response to Water Stress in Endosperm of High-Starch Maize

以郑单21为试验材料,利用透射电镜(TEM:Transmission Electron Microscope)和激光粒度分析仪研究水分胁迫下玉米胚乳淀粉粒的形态和粒度分布。结果表明:水分胁迫导致玉米籽粒形态建成滞后,尤其是内、外珠被组织解体和胚乳淀粉粒积累的速度减缓。授粉后7天,水分胁迫处理的籽粒外珠被尚未退化消失,果皮、内珠被和胚乳细胞的界限模糊,几乎每个果皮细胞内都含有细胞核;而正常供水处理的玉米籽粒外珠被已退化消失,果皮、内珠被和胚乳细胞的界限清晰,果皮细胞内容物较少,细胞壁较薄,内珠被细胞明显较大,内容物少,绝大多数细胞无细胞核。授粉后11天,两处理的胚乳细胞的细胞壁明显变薄,细胞内容物显著增多,细胞内已明显可见大大小小的淀粉粒,但正常供水处理的淀粉粒明显大且多。水分胁迫处理的淀粉粒表面积、数目和体积分布均呈单峰曲线,而正常供水处理表现为淀粉粒数目分布呈单峰曲线,表面积分布和体积分布呈双峰曲线。水分胁迫可降低A型淀粉粒的表面积、数目和体积百分比,增加B型淀粉粒的表面积、数目和体积百分比。

With the maize cuhivar Zhengdan 21 as experiment material, the morphology and granularitydistribution of endosperm starch granules under water stress were studied with transmission electron microscope and laser particle size analyzer. The results showed that water stress made the morphogenesis of maize grain lag, especially made the disintegration of inner and outer integument and the accumulation of endosperm starch granules slow down. On the 7th day after pollination, the outer integument did not yet disappear under water stress; the boundary between pericarp, inner integument and endosperm cell was fuzzy; almost every pericarp cell had nucleus. But under normal water treatment, the outer integument of maize grain had disappeared; the boundary between pericarp, inner integument and endosperm cell was clear; for the pericarp cell, the content was fewer and the cell wall was thinner; inner integument cell was obviously larger, but had less content, andmost of them had no nucleus. On the 11 th day after pollination, the endosperm cell wall became thin obvious- ly, but their content increased significantly with many visible starch granules; the starch granules under nor- mal water treatment were obviously larger and more than those under water stress. All of the distribution of su- perficial area, number and volume of starch granules under water stress showed unimodal curve; under normal water treatment, the number distribution of starch granules showed unimoda｜ curve, while the distribution of superficial area and volume showed bimodal curve. Water stress could decrease the superficial area, number and volume of A type starch granules, but increase those of B type.