大麦淀粉胚乳发育期间程序性细胞死亡的研究

 【目的】大麦胚乳发育过程中，淀粉胚乳细胞变成死细胞，本研究阐明这种死亡方式是一种特殊形式的程序性细胞死亡（PCD）。【方法】利用透射电镜和荧光显微镜观察淀粉胚乳细胞核的结构变化，利用琼脂糖凝胶电泳和TUNEL检测DNA断裂，并对抗氧化酶活性动态和籽粒灌浆速率进行测量。【结果】伴随淀粉胚乳发育进程，大麦淀粉胚乳细胞核呈现出核变形、染色质凝集、核膜破裂和核瓦解形成核残体等一系列PCD过程中核的变化特征。琼脂糖凝胶电泳和TUNEL结果都表明，核DNA发生了有规律的断裂，但DAPI染色结果却表明，核残体并没有从死亡的淀粉胚乳细胞中消失，而是分散存在于淀粉粒之间。Evan’s blue染色表明，死亡的淀粉胚乳细胞在胚乳组织中是随机发生的。在淀粉胚乳细胞核衰退解体和无核的胞质发育过程中，胚乳内抗氧化酶都存在一定的活性，籽粒的粒重也在不断增加。【结论】大麦淀粉胚乳在核衰退解体和无核化的胞质发育时期，胚乳细胞维持较高的代谢活性，没有表现衰退解体特征，直到被贮藏物质所充实才死亡，淀粉胚乳细胞的发育是一种特殊形式的PCD过程。

Studies on the Programmed Cell Death in Barley During Starchy Endosperm Development

【Objective】 Barley starchy endosperm cell has become dead cell during endosperm development, the purpose of this study was to reveal that the death of starchy endosperm was a special form of programmed cell death (PCD). 【Method】 Structural morphology of nucleus was observed with transmission electron microscope and fluorescence microscope, the breakage of nuclear DNA was analyzed with agarose gel electrophoresis and TUNEL, the activity of antioxidant enzyme and grain filling ratio were also investigated. 【Result】 The nucleus of barley starchy endosperm showed nucleus deformation, chromatin condensation, nuclear envelope disruption, and nuclear residue formation from degraded nucleus, which were typical features of PCD, along with the development of the starchy endosperm in barley. Breakage of nuclear DNA was observed with agarose gel and TUNEL method. Nuclear residues, which were not completely lost, were observed among starch granules in starchy endosperm cells after staining with DAPI. Evan’s blue staining indicated that starchy endosperm cell death occurred unsynchronously among the starchy endosperm cells with initiation points randomly distributed in the endosperm tissue. Antioxidant enzymes showed high activities, and grain weight increased during degradation of nucleus and development of cytoplasm without nucleus. 【Conclusion】 Barley starchy endosperm cell remained alive, kept its normal metabolism, the synthesis and accumulation of starch and storage protein during degradation of nucleus and developemt of cytoplasm without nucleus. The starchy endosperm cell finally become death cell when it is completely filled with reserves. The development of starchy endosperm in barley is a special form of PCD.