Abstract:

Short-day (SD) induced the plant senescence in pumpkin (Cucurbita pepo Linn.) strain 185. Structural assay, gene expression and a series of biochemical analyses were performed to analyze the senescence mechanism in pumpkin strain 185 exposed to SD. Two aspects of important changes initiated in SD exposure contributed to the senescence process. SD functionally led to the initiation of the apical transformation from vegetative to reproductive growth, and then programmed cell death (PCD) in the apical meristem, causing the loss of vigorous growth activity. Moreover, SD treatment resulted in the formation of a great number of dying cells in mesophyll tissue later in the development compared with the phenotype of plants under long-day (LD) conditions. During the senescence process, high expression of nuclease is an important molecular event. These results indicate that the initiation of senescence process in pumpkin stain 185 plants is closely related to the death of cells in apical meristem and mesophyll. 

光周期对西葫芦185品系顶芽和叶片衰老的调控

王大勇  胡爽  李晴  崔克明^*  朱玉贤^*

(北京大学生命科学学院,北京 100871)

摘要：在短日照下 ,西葫芦 (Cucurbita pepo Linn.) 185品系的植株发生衰老。结构学、基因表达与系列生化分析证实:短日照启动了顶端分生组织由营养生长锥向花芽的转化 ,进而其组成细胞发生编程性死亡 (PCD) ,导致顶端生长势的丧失 ;与长日照处理相比 ,短日照处理在发育晚期也引起大量叶肉细胞发生PCD ,进而叶片出现衰老。核酸酶活性的高度表达是PCD过程中一个非常重要的分子事件。实验证实,西葫芦 185品系植株衰老进程的发生与顶端分生组织和叶肉细胞中发生PCD密切相关。

关键词: 光周期 衰老 细胞编程性死亡

 ^*通讯作者

Key words: photoperiod, senescence, programmed cell death