Morphological Changes in Nucellar Cells Undergoing Programmed Cell Death (PCD) During Pollen Chamber Formation in Ginkgo biloba
Morphological Changes in Nucellar Cells Undergoing Programmed Cell Death (PCD) During Pollen Chamber Formation in Ginkgo biloba
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发表时间：
2003
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通讯作者：
Li Da;L. Cheng
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作者：
Li Da;L. Cheng
银杏珠孔端珠心细胞程序性死亡(PCD)参与了银杏花粉室形态的发生。在PCD过程中，珠心细胞通过有序的过程降解其细胞成分。在液泡化过程中，细胞质被扩大的液泡吞噬，留下了各种细胞器，在形态上保持完整。随着液泡化的继续，液泡崩解，液泡膜破裂，胞浆完全消失。细胞器随后被摧毁。最终，珠心细胞消化掉了所有的细胞质，留下了细胞壁。随着珠心的发育，它们变得塌陷。细胞内的细胞膜发生了显著的变化，在导致细胞死亡方面发挥了作用。其中一些明显的变化是出现多泡小体、多循环样膜、含有一些细胞器的膜结合体、液泡膜破裂和大量小泡。顶端表皮的裂开似乎遵循两种不同的途径，一种涉及特定的表皮细胞自溶，另一种是由相邻的两个表皮细胞从中层脱离，而不是细胞自溶。特定的表皮细胞在顶端表皮开裂之前就已经死亡，这标志着随后开裂的位置。根据细胞形态的变化，论证了珠心细胞PCD在花粉室形成过程中的过程。
Programmed cell death (PCD) of the nucellar cells at the micropylar end is involved in pollen chamber morphogenesis in Ginkgo biloba L. A development-course observation of the morphological changes in the nucellar cells undergoing PCD to form pollen chamber was performed. During the PCD, the nucellar cells degraded their cellular components through an orderly progression. Through the vacuolation, the cytosol was engulfed by the enlarging vacuole, leaving out various organelles, which remained morphologically integrated. As the vacuolation continued, the vacuole collapsed with the breakage of the tonoplast and the cytosol disappeared completely. Organelles were subsequently destroyed. Ultimately, nucellar cells digested away all of their cytoplasm, leaving with cell walls. They became collapsed as the nucellus developed. Intracellular membranes were strikingly changed, playing a role in leading to cell death. Some of these noticeable changes were the appearance of multivesicular body, multicycle-like membranes, membrane-bounded bodies containing some organelles, tonoplast rupture and numerous vesicles. The dehiscence of the apical epidermis, resulting in the opening, appeared to have followed two different pathways with one involving a specific epidermal cell autolysis and the other by detachment from middle lamella of two neighboring epidermal cells without cell autolysis. The specific epidermal cells had been dead prior to the dehiscence of the apical epidermis, which marked the sites of the dehiscence followed. In view of the changes in the cellular morphology, a process of nucellar cell PCD in the course of the pollen chamber formation was demonstrated.