不同冷敏感型甘蔗茎尖Ca2+和Ca2+-ATP酶活性对低温的响应

摘要

为了探明不同冷敏感型甘蔗品种茎尖Ca2+和Ca2+-ATP酶活性对低温胁迫的响应机制,本研究利用植物组织化学技术结合电子显微镜观察了2个不同冷敏感型甘蔗品种茎尖在低温胁迫前后Ca2+和Ca2+-ATP酶的变化规律.供试品种为桂糖28号(抗冷型)和园林6号(冷敏感型),在0℃条件下,分别处理0、2、4和6 d后切取茎尖进行组织化学定位,获得如下结果:1)低温胁迫前后桂糖28号形态和细胞结构变化不明显,但园林6号发生质壁分离现象,线粒体空泡化,细胞崩溃,组织水溃状明显;2)低温胁迫开始,2个甘蔗品种细胞质和细胞核Ca2+沉淀颗粒均增多,但随着低温胁迫时间的延长桂糖28号细胞质和细胞核Ca2+沉淀颗粒减少,并维持在一个低稳态水平,而园林6号细胞质和细胞核一直维持在高Ca2+浓度水平;3)低温对桂糖28号Ca2+-ATP酶活性与分布影响不大,其活性一直维持在较高水平,而园林6号Ca2+-ATP酶活性随着低温胁迫时间的延长而变弱.结果说明,低温条件下细胞质和细胞核Ca2+浓度增高是导致甘蔗茎尖细胞受伤害的重要原因,维持较高Ca2+-ATP酶活性有助于避免Ca2+-中毒.%Low temperature in winter is an adverse abjotic stress to sugarcane industry,and caused significant lose. In order to investigate the response of Ca2+ and Ca2+-ATPase activity in the stem tip of different cold sensitivity sugarcane cultivars, Electron microscope (EMS) and phytohistochemistry technology were employed to detect the changes of Ca2+ level and Ca2+ -ATPase activity in the stem tips of two sugarcane varieties YL6 (cold sensitive) and GT28 (cold resistant) before and after low temperature treatment. The plants were treated at 0 ℃ in fridge and samples were taken after treatment at 0,2,4 and 6 d, respectively. The results showed that there was no significant morphological difference and cellular structures in the stem tip of GT28 before and after low temperature stress. On the contrary,the cells in the stem tip of YL6 showed plasmolysis with mitochondria vacuolization, the cells were distorted and broken down, and the tissues were fully hygrophanous with the ongoing of the stress. Both sugarcane cultivars showed accumulation of Ca2+ pellets in cytoplasm and nucleolus of the stem tip cells at the beginning of low temperature stress. The accumulated Ca2+ pellets in GT28 decreased and maintained at low level with the ongoing of the stress,but those in YL6 maintained at high level. Low temperature stress showed very little influence on the Ca2+-ATPase activity and its distribution in GT28, which kept high-level. On the contrary, Ca2+-ATPase activity in YL6 reduced with the ongoing of stress. In conclusion,high level of Ca2+ in cytoplasm is one of the important reasons that responsible for cell injury,while high Ca2+ -ATPase activity might play an important role in avoiding high Ca2+ toxicity.