木薯高、低粉品种贮藏根生长关键期的生理生化特性比较

Comparison of Physiological and Biochemical Properties of Storage Roots Between High and Low Starch Cultivars of Cassava during the Critical Growth Period

通过研究木薯Manihot esculenta高粉和低粉品种贮藏根在发育关键期(形成–膨大期)主要生理生化性质的差异及其动态变化,为木薯栽培管理和育种改良提供理论基础。对高粉木薯品种‘辐选01’(FX01)和‘Kasetsart 50’(KU50)以及低粉品种‘华南124’(SC124)和‘9I’于种植后120、130、140、151和165 d五个时期分别取贮藏根样品,测定淀粉、可溶性糖、脱落酸(ABA)、保护酶、活性氧(ROS)、丙二醛(MDA)等生理生化指标并分析变化规律。结果表明,可溶性糖含量在贮藏根皮层中始终高于淀粉储藏区;高粉品种中总可溶性糖含量在贮藏根膨大期快速增加,且表现出较高的抗氧化酶活性和较低的ROS及MDA含量;ABA含量呈现出高粉品种比低粉品种低的趋势。木薯低粉和高粉品种中可溶性糖的分布与其转运后合成淀粉的规律相一致,高粉品种中淀粉的积累速率始终高于低粉品种,其较高的抗氧化酶活性和较低的ROS及MDA含量有利于木薯贮藏根中淀粉的积累。

This study explored the differences and dynamic changes in the main physiological and biochemical characteristics of roots in high and low starch cultivars of cassava(Manihot esculenta)at key developmental stages(storage root formation and bulking),providing a theoretical basis for cassava management and breeding improvement.Storage root samples of high starch cassava varieties‘FX01’and‘KU50’and low starch cassava varieties‘SC124’and‘9I’were selected at 120,130,140,151 and 165 days after planting,respectively.The physiological and biochemical indexes of starch,soluble sugar,abscisic acid(ABA),protective enzyme,malonaldehyde(MDA)and reactive oxygen species(ROS)were measured and analyzed.The results showed that the soluble sugar content in the cortex of storage root was always higher than that in starch storage area.The soluble sugar contents of the high starch varieties increased rapidly during the expansion period of storage root,and showed higher antioxidant enzyme activities and lower ROS and MDA contents.ABA contents of high starch varieties were lower than those of low starch varieties.Analyzing the effects of these physiological and biochemical parameters on starch accumulation,it was found that the distribution of soluble sugar in low starch and high starch varieties was consistent with the law of starch synthesis after transportation.The starch accumulation rate in high starch varieties was always higher than that in low starch varieties.Their higher antioxidant enzyme activities and lower ROS and MDA contents were conducive to the starch accumulation in cassava storage roots.