A comparative ultrastructural study of pit membranes with plasmodesmata associated thickenings in four angiosperm species.
A comparative ultrastructural study of pit membranes with plasmodesmata associated thickenings in four angiosperm species.
复制标题
四种被子植物物种中胞间连丝相关增厚的纹孔膜的比较超微结构研究。
DOI：
10.1007/s00709-008-0019-2
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发表时间：
2008
期刊：
影响因子：
2.9
通讯作者：
Rabaey D
中科院分区：
文献类型：
--
作者：
Rabaey D
最近对被子植物凹坑膜的微形态观察扩大了气管元件中具有假托里的类群的数量和范围。本研究在超微结构水平 (TEM) 上研究了无关的云南海棠、女贞、海桐和越橘中假托里的发育，以确定这些胞间连丝相关的增厚是否在开花植物中具有相似的发育模式。在早期个体发育阶段，观察到初级增厚的形成，这是由于纤维管胞和导管元件中的凹坑膜肿胀所致。由于胞间连丝似乎经常（但并非总是）与这些初级凹坑膜增厚相关，因此尚不清楚哪些超微结构特征控制假环面的形成。在木质部分化的最后阶段，次生增厚沉积在初级纹孔膜增厚上。在这些最后的发育阶段，胞连丝总是与假托里相关。自溶后，二次增稠物变得电子致密且持久，而初级增稠物变得透明并部分或完全溶解。在所研究的物种中观察到的发育模式是相似的，并且与之前的蔷薇科个体发育研究一致，这表明假花托可能是被子植物中的同源特征。
Recent micromorphological observations of angiosperm pit membranes have extended the number and range of taxa with pseudo-tori in tracheary elements. This study investigates at ultrastructural level (TEM) the development of pseudo-tori in the unrelatedMalus yunnanensis,Ligustrum vulgare,Pittosporum tenuifolium, andVaccinium myrtillusin order to determine whether these plasmodesmata associated thickenings have a similar developmental pattern across flowering plants. At early ontogenetic stages, the formation of a primary thickening was observed, resulting from swelling of the pit membrane in fibre-tracheids and vessel elements. Since plasmodesmata appear to be frequently, but not always, associated with these primary pit membrane thickenings, it remains unclear which ultrastructural characteristics control the formation of pseudo-tori. At a very late stage during xylem differentiation, a secondary thickening is deposited on the primary pit membrane thickening. Plasmodesmata are always associated with pseudo-tori at these final developmental stages. After autolysis, the secondary thickening becomes electron-dense and persistent, while the primary thickening turns transparent and partially or entirely dissolves. The developmental patterns observed in the species studied are similar and agree with former ontogenetic studies in Rosaceae, suggesting that pseudo-tori might be homologous features across angiosperms.