PDF(Pubmed)
Abstract：
Evolution of cellular characteristics is a fundamental aspect of evolutionary biology, but knowledge about evolution at the cellular level is very limited. In particular, whether a certain intracellular characteristic evolved in angiosperms, and what significance of such evolution is to angiosperms, if it exists, are important and yet unanswered questions. We have found that bidirectional cytokinesis occurs or likely occurs in male meiosis in extant basal and near-basal angiosperm lineages, which differs from the unidirectional cytokinesis in male meiosis in monocots and eudicots. This pattern of cytokinesis in angiosperms seems to align with the distribution pattern of angiosperms with the lineages basal to monocots and eudicots living in tropical, subtropical or temperate environments and monocots and eudicots in an expanded range of environments including tropical, subtropical, temperate, subarctic and arctic environments. These two cytokinetic modes seem to result from two phragmoplast types, respectively. A phragmoplast in the bidirectional cytokinesis dynamically associates with the leading edge of a growing cell plate whereas a phragmoplast in the unidirectional cytokinesis is localized to an entire division plane. The large assembly of microtubules in the phragmoplast in unidirectional cytokinesis may be indicative of increased microtubule stability compared with that of the small microtubule assembly in the phragmoplast in bidirectional cytokinesis. Microtubules could conceivably increase their stability from evolutionary changes in tubulins and/or microtubule-associated proteins. Microtubules are very sensitive to low temperatures, which should be a reason for plants to be sensitive to low temperatures. If monocots and eudicots have more stable microtubules than other angiosperms, they will be expected to deal with low temperatures better than other angiosperms. Future investigations into the male meiotic cytokinetic directions, microtubule stability at low temperatures, and proteins affecting microtubule stability in more species may shed light on how plants evolved to inhabit cold environments.
摘要：
细胞特征的进化是进化生物学的一个基本方面，但是关于细胞水平进化的知识非常有限。特别是,被子植物是否进化了某种细胞内特性，这种进化对被子植物有什么意义，如果它存在，是重要但尚未回答的问题。我们已经发现，在现存的基底和近基底的被子植物谱系中，在男性减数分裂中发生或可能发生双向胞质分裂。这与单子叶植物和单子叶植物的男性减数分裂中的单向胞质分裂不同。被子植物的这种胞质分裂模式似乎与被子植物的分布模式一致，其谱系以单子叶植物和生活在热带的eudicots为基础，亚热带或温带环境以及单子叶植物和eudicots在包括热带在内的更广泛的环境中，亚热带,温带,亚北极和北极环境。这两种细胞动力学模式似乎是由两种原生质体类型产生的，分别。双向胞质分裂中的原生质体与生长中的细胞板的前缘动态关联，而单向胞质分裂中的原生质体定位于整个分裂平面。与双向胞质分裂中的原生质体中的小微管组装相比，单向胞质分裂中的原生质体中的微管大组装可能表明微管稳定性增加。微管可以从微管蛋白和/或微管相关蛋白的进化变化中增加其稳定性。微管对低温非常敏感,这应该是植物对低温敏感的原因。如果单子叶植物和eudicots比其他被子植物有更稳定的微管，他们将有望比其他被子植物更好地处理低温。对男性减数分裂细胞动力学方向的未来研究，微管在低温下的稳定性，在更多物种中影响微管稳定性的蛋白质可能会揭示植物如何进化到栖息在寒冷环境中。
