蒙古莸幼苗干旱致死过程中非结构性碳水化合物的变化

Changes of non-structural carbohydrates in Caryopteris mongolica seedlings during the process of drought-induced mortality

以一年生蒙古莸幼苗为对象,设置适宜水分、慢速干旱致死和快速干旱致死3个处理,研究不同干旱强度致死下蒙古莸幼苗各器官中非结构性碳水化合物(NSC,包括可溶性糖和淀粉)的含量变化及其分配规律.结果表明:慢速干旱致死胁迫下各器官可溶性糖含量与适宜水分组无显著差异.随时间的推移,茎可溶性糖含量先增加后减少,淀粉和NSC含量增加;粗根可溶性糖含量减少,淀粉和NSC含量增加;叶可溶性糖含量增加,淀粉和NSC含量减少.致死时(80 d),叶、茎、粗根和细根的NSC含量分别为6.2%、7.8%、8.3%和7.4%.快速干旱致死胁迫下,各器官可溶性糖含量均高于适宜水分处理组,而淀粉和NSC含量均低于适宜水分组.随时间的推移,根可溶性糖含量下降,淀粉和NSC含量上升;茎可溶性糖、淀粉和NSC含量均上升;叶可溶性糖含量上升,淀粉和NSC含量下降.致死时(30 d),叶、茎、粗根和细根的NSC含量分别为5.9%、6.6%、8.9%和7.7%.应对不同的干旱致死情况,蒙古莸幼苗各器官间非结构性碳水化合物呈现出不同的动态变化.在慢速干旱致死胁迫下,NSC优先为维持各器官生理代谢活动提供能量;而在快速干旱致死下,NSC主要以可溶性糖形式维持植物代谢,调节渗透势,促进吸水,应对急剧的干旱胁迫.

The changes and distribution of non-structural carbohydrate (NSC, including soluble sugar and starch) content in different organs of one-year-old Caryopteris mongolica seedlings were investigated under suitable water condition (CK), slow-dying drought stress, and fast-dying drought stress. There was no significant difference in soluble sugar content of all organs between slow-dying drought stress and CK. With the extended duration of drought, the soluble sugar content in stem increased firstly and then decreased, while starch and NSC contents decreased. The soluble sugar content in coarse roots decreased, while starch and NSC contents increased. The soluble sugar content in leaves increased, while starch and NSC contents of leaves decreased. The NSC content of leaves, stems, coarse roots and fine roots were 6.2%, 7.8%, 8.3% and 7.4% at the death time (80 days), respectively. Under fast-dying drought stress, soluble sugar content in all organs was higher than that in CK, while starch and NSC contents were lower than that in CK. With the increasing time, soluble sugar content of roots decreased, while starch and NSC contents increased. The soluble sugar, starch and NSC contents in stems increased. The soluble sugar content of leaves increased, while starch and NSC contents decreased. The NSC content of leaves, stems, coarse roots and fine roots were 5.9%, 6.6%, 8.9% and 7.7% at lethal time (30 days), respectively. Under different drought stress, non-structural carbohydrates among different organs of C. mongolica seedlings showed different dynamics. Under slow-dying drought stress, NSC gave priority to allocate energy for maintaining physiological metabolism of organs. Under fast-dying drought stress, NSC mainly maintained plant metabolism in the form of soluble sugar, regulated osmotic potential, promoted water absorption, and coped with drastic drought stress.