The growth of the pollen tube wall of Oenothera is effected by the expulsion of fibrillar material from the cytoplasm into the developing wall. This material may also be seen in the cytoplasm, contained in membrane-bound vesicles. It is not clear how the content of the vesicles is discharged, but it appears not to involve the participation of microtubules. The source of the cytoplasmic fibrillar bodies depends upon the stage of development of the pollen tube. The earilest growth is derived from the inclusion into the wall of vesicles containing pre-formed materials present in the grain on pollination. During the next stage of growth the wall is derived from the content of double-membraned inclusions also present in the pollen. The content of the former vesicles is not so similar to the wall as the latter, but intermediates between the 2 types of vesicle may be seen in the cytoplasm, indicating that the former are formed from the latter. Most of the tube wall is derived from the products of dictyosomes in the pollen grain or tube. These dicytosomes are few in number and they must be exceedingly active. This, and the observation that dictyosome vesicles are frequently associated with banked complexes of mitochondria, indicates that some steps in the metabolism of the vesicular content, perhaps phosphorylation, take place distant from the dicytosomes. These different sources of fibrillar material presumably permit the rapid starting of tube growth, without any attendant metabolism. However, it would be impossible to include enough pre-formed wall material in the grain to enable the full growth of the tube, so once started, it seems that the tube then relies on the elaboration of simple reserves for the contruction of its wall. These reserves are likely to be held in the pollen, and may be the large numbers of starch grains characteristic of the pollen cytoplasm.

译文

卵生花粉管壁的生长是通过将原纤维物质从细胞质中排出到发育中的壁中而实现的。这种物质也可以在细胞质中看到,包含在膜结合的囊泡中。尚不清楚如何释放囊泡的含量,但似乎不涉及微管的参与。细胞质原纤维体的来源取决于花粉管的发育阶段。最早的生长来自包含在授粉时谷物中存在的包含预形成材料的囊泡壁。在生长的下一阶段,壁来自花粉中也存在的双层包裹体的含量。前者囊泡的含量不像后者那样与壁相似,但在细胞质中可能看到2种囊泡之间的中间体,表明前者是由后者形成的。大部分的管壁来源于花粉粒或管中双子体的产物。这些二胞体数量很少,它们必须非常活跃。这以及观察到dictyosome囊泡经常与线粒体的银行复合物有关,这表明囊泡含量代谢的某些步骤 (可能是磷酸化) 发生在远离二胞体的地方。这些不同的原纤维物质来源可能允许快速开始管生长,而没有任何伴随的代谢。但是,不可能在谷物中包括足够的预成型壁材料以使管完全生长,因此一旦开始,管似乎就依赖于简单的储备来构造其壁。这些储备很可能存在于花粉中,并且可能是花粉细胞质特有的大量淀粉粒。

+1
+2
100研值 100研值 ¥99课程
检索文献一次
下载文献一次

去下载>

成功解锁2个技能,为你点赞

《SCI写作十大必备语法》
解决你的SCI语法难题!

技能熟练度+1

视频课《玩转文献检索》
让你成为检索达人!

恭喜完成新手挑战

手机微信扫一扫,添加好友领取

免费领《Endnote文献管理工具+教程》

微信扫码, 免费领取

手机登录

获取验证码
登录