棉花叶片衰老过程中激素和膜脂过氧化的关系

以陆地棉品种辽棉9号的去根幼苗为材料,对其进行暗诱导衰老培养.在培养液中分别加入6-BA、ABA、GSH、H2O2、CaCl2、A23187 和A23187 CaCl2,测定在不同培养条件下棉花去根幼苗叶片内源激素、SOD酶活性和MDA含量的变化.结果表明:棉花叶片衰老表现为细胞分裂素含量的下降和ABA含量的上升.6-BA、GSH和钙离子均延缓叶片的衰老,ABA和H2O2促进叶片的衰老.

The Relationship Between Hormone and Membrance Lipid Peroxidation in Cotton Leaf During Senescence

Roots were removed from seedings of cotton cv. Liaomian No 9. Then the rootless seedings were cultured in darkness with a solution containing 6-BA, ABA, GSH, H 2O 2, CaCl 2, A23187, A23187+CaCl 2. The endogenous hormone content, SOD activity and malondialdehye (MDA) content in leaves of the cotton seedings were measured during dark -induced senescence. The dark-induced senescence of the rootless seedings was characterized by a decrease in chlorophyll and protein levels (Fig.1). Since protein loss was prior to chlorophyll loss, the senescence of rootless seedings was monitored by the decrease of protein in the present study. Treatment with 6-BA, which retarded dark-induced leaf senescence, increased cytokinin contents and SOD activity, and decreased ABA contents and MDA level in the leaves of rootless cotton seedings (Table 1). Treatment with ABA was contrary to 6-BA. Although GSH and calcium ions did not affect the content of cytokinin and ABA, and SOD activity, they delayed dark-induced senescence. H 2O 2, which accelerated dark-induced leaf senescence, increased MDA level, but it did not affect endogenous hormone content and SOD activity (Table 1). The above results suggested that endogenous hormone and free radical scavengers, such as GSH and SOD enzyme, might be involved in regulating dark-induced leaf senescence. Evidence was presented to show that the dark-induced leaf senescence of the rootless cotton seedings might attribute to decreased cytokinin content.