不同淀粉含量木薯品种块根淀粉粒结构观察比较

目的]探讨不同淀粉含量木薯品种块根淀粉粒结构差异及其与淀粉含量的潜在关系,为研究木薯块根淀粉存储状态及品种选育提供理论依据.方法]以高淀粉木薯品种GR891、辐选01和低淀粉木薯品种华南124为材料,通过块根形态解剖、石蜡切片观察、电镜扫描等方法比较不同淀粉含量木薯块根淀粉粒的结构特点.结果]苗期时木薯块根淀粉主要存在于次生木质部.块根形成期淀粉粒大量存在;淀粉储藏区是木薯块根淀粉储藏的最主要区域,皮层部分少量分布,储藏区淀粉粒密度高于皮层;靠近中柱的次生木质部区域,其淀粉粒呈放射线状排列分布.不同淀粉含量木薯品种在淀粉粒形态上无明显差别,多数为一面不规则的半球形、椭球形.高淀粉品种的淀粉粒直径小于低淀粉品种,但差异不显著(P>0.05).结论]木薯块根淀粉积累的主要位置是淀粉储藏区,导管内部及临近区域的淀粉粒数量多、直径小、填充程度高,且在块根膨大期高淀粉木薯品种淀粉粒聚集程度高于低淀粉木薯品种.

Starch grain structure in root tuber of cassava varieties with different starch contents

Objective]Starch grain structure in root tuber of cassava varieties with different starch contents and its re-lation to starch content were studied, so as to provide theoretical basis for starch storage and breeding of cassava.Method]Taking high-starch cassava varieties GR891,Fuxuan 01 and low-starch cassava variety SC124 as materials, the starch grain structure in root tuber of different cassava varieties were studied by morphology anatomy ,paraffin section and scanning electron microscopy of root tuber. Result]At seedling stage, starch was mainly stored in secondary xylem. At root tuber formation stage, starch grains were abundant. Most of them were stored at starch storage area and a small amount were distributed at cortex, but starch grain density in starch storage area was higher than that in cortex. In secondary xylem region near the middle column,starch grains were distributed in a radial arrangement. There was no significant difference in morphology of starch grains between different cassava varieties,and most of them were irregular semicircle and elliptical. Starch grain diameter of high-starch varieties was smaller than that of low-starch varieties , but the difference was insignif-icant(P>0.05). Conclusion]The main position of starch accumulation in root tuber of cassava is starch storage area. In catheter interior and adjacent areas, the number of starch grain is large, grain diameter is small, and filling degree is high. Aggregation degree of starch grain in high-starch cassava varieties is higher than that of low-starch cassava varieties at root tuber formation stage.