Lan Sheng Yin, Zhong Fang Xu, Yang Ze Min, Jin De Ming, Xu Zhen Xiu
College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Shi Yan Sheng Wu Xue Bao. 2004 Feb;37(1):34-44.
The cellular ultrastructural morphology, grain filling ratio and activity of related enzymes during denucleation development stage in starchy endosperm cell of an Indica rice variety Zhongxian 8836 were observed and analyzed. The endosperm cellularization was completed at about the 3rd day after flowering (DAF). At 5 DAF a few endosperm cells initiated denucleation development. At 13 DAF almost all the starchy endosperm cells completed their denucleation. The nuclear degradation is the first stage of programmed cell death (PCD) in starchy endosperm. It occurred unsynchronously among different starchy endosperm cells. The nuclear degradation of starchy endosperm cell during denucleation development stage showed not only morphological features commonly observed in animal and plant PCD, but also some unique characteristics. Mitochondria degeneration was observed along with nuclear degradation, indicating there were interrelations between the two processes. Enzymes related to PCD, such as super-oxide dismutases (SOD) and catalase (CAT), as well as enzymes related to starch synthesis, such as ADP-glucose pyriphosphorylase (AGP), soluble starch synthase (SSS) and starch branching enzyme or Q-enzyme, showed very high activity during the denucleation development stage. Maximum grain filling rate and grain weight increase were also achieved in the denucleation developing stage of most starch endosperm cells. The denucleated cell remained alive in the developing endosperm, keeping its normal metabolisms, the synthesis and accumulation of starch and storage proteins. However, enzyme activities and grain filling rate were apparently dropped to a lower level after denucleation. The starchy endosperm cell finally completed its PCD process when it was completely filled with reserves. Evan's blue staining indicated that cell death occurred unsynchronously among the starchy endosperm cells with initiation points randomly distributed in the endosperm tissue.
对籼稻品种中仙8836淀粉胚乳细胞去核发育阶段的细胞超微结构形态、籽粒充实率及相关酶活性进行了观察与分析。胚乳细胞化在开花后约第3天完成。开花后5天,少数胚乳细胞开始去核发育。开花后13天,几乎所有淀粉胚乳细胞完成去核。核降解是淀粉胚乳中程序性细胞死亡(PCD)的第一阶段。它在不同的淀粉胚乳细胞中不同步发生。淀粉胚乳细胞在去核发育阶段的核降解不仅表现出动植物PCD中常见的形态特征,还具有一些独特的特征。观察到线粒体退化与核降解同时发生,表明这两个过程之间存在相互关系。与PCD相关的酶,如超氧化物歧化酶(SOD)和过氧化氢酶(CAT),以及与淀粉合成相关的酶,如ADP-葡萄糖焦磷酸化酶(AGP)、可溶性淀粉合酶(SSS)和淀粉分支酶或Q酶,在去核发育阶段表现出非常高的活性。大多数淀粉胚乳细胞在去核发育阶段也实现了最大籽粒充实率和粒重增加。去核细胞在发育中的胚乳中保持存活,维持其正常代谢、淀粉和贮藏蛋白的合成与积累。然而,去核后酶活性和籽粒充实率明显下降到较低水平。当淀粉胚乳细胞完全充满贮藏物时,最终完成其PCD过程。伊文思蓝染色表明,淀粉胚乳细胞中的细胞死亡不同步发生,起始点随机分布在胚乳组织中。