...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Protoplasma: An International Journal of Cell Biology >Pollen embryogenesis: atavism or totipotency?
【24h】

Pollen embryogenesis: atavism or totipotency?

机译：花粉胚胎发生：虚弱还是全能？

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The origins of pollen embryogenesis are still in doubt. Totipotency of plant cells has traditionally been put forward as an explanation for this phenomenon but we have found this interpretation to involve some shortcomings. The pollen grain is a highly differentiated structure which should have a very reduced capability of regenerating a whole plant, whereas in some species the induction of androgenesis appears to occur with greater facility than somatic embryogenesis. Furthermore, some microspores seem to have a tendency to morphogenesis and organogenesis; spontaneous androgenesis occurs naturally in various species and many examples also occur of pollen dimorphism. Totipotency would seem to be insufficient to explain androgenesis and we propose that its origin might be found in the phenomenon of atavism. According to studies published on ancestral precursors of pollen, these structures appear to have had high proliferation capacity. The ability to form a multicellular structure from a single haploid cell is shared by the meiocytes of ancestral algae, of the first land plants, and of present-day ferns, which are evolutionarily related to pollen. Atavism is only expressed under certain circumstances, as indeed is androgenesis, normally as a consequence of an environmental stress. Out conclusion is that there is evidence enough to suggest that androgenesis may well be the expression of archaic genes of meiocytes with morphogenic capacity which were naturally expressed in the ancestors of flowering plants. [References: 40]
机译：花粉胚胎发生的起源仍然值得怀疑。传统上已经提出了植物细胞的全能性来解释这种现象，但是我们发现这种解释存在一些缺陷。花粉粒是高度分化的结构，其再生整个植物的能力应大大降低，而在某些物种中，与体细胞胚发生相比，发生雄激素的诱导似乎具有更大的便利性。此外，一些小孢子似乎具有形态发生和器官发生的趋势。自发雄激素自然发生在各种物种中，并且许多例子还发生花粉二态性。全能似乎不足以解释雄激素的生成，我们建议它的起源可能存在于畸形现象中。根据有关花粉祖先的研究，这些结构似乎具有很高的增殖能力。由单个单倍体细胞形成多细胞结构的能力由祖先藻类，第一批陆生植物和当今蕨类的卵母细胞共有，它们与花粉进化相关。通常在环境压力的作用下，仅在某些情况下才会表现出虚构性，而雄激素的生成确实如此。得出的结论是，有足够的证据表明雄激素生成很可能是在开花植物的祖先中自然表达的具有形态发生能力的微细胞的过时基因的表达。 [参考：40]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号