Dorrell Richard G, Smith Alison G
Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom.
Eukaryot Cell. 2011 Jul;10(7):856-68. doi: 10.1128/EC.00326-10. Epub 2011 May 27.
The chromalveolate "supergroup" is of key interest in contemporary phycology, as it contains the overwhelming majority of extant algal species, including several phyla of key importance to oceanic net primary productivity such as diatoms, kelps, and dinoflagellates. There is also intense current interest in the exploitation of these algae for industrial purposes, such as biodiesel production. However, the evolution of the constituent species, and in particular the origin and radiation of the chloroplast genomes, remains poorly understood. In this review, we discuss current theories of the origins of the extant red alga-derived chloroplast lineages in the chromalveolates and the potential ramifications of the recent discovery of large numbers of green algal genes in chromalveolate genomes. We consider that the best explanation for this is that chromalveolates historically possessed a cryptic green algal endosymbiont that was subsequently replaced by a red algal chloroplast. We consider how changing selective pressures acting on ancient chromalveolate lineages may have selectively favored the serial endosymbioses of green and red algae and whether a complex endosymbiotic history facilitated the rise of chromalveolates to their current position of ecological prominence.
色藻界“超群”是当代藻类学的关键研究对象，因为它包含了绝大多数现存的藻类物种，包括对海洋净初级生产力至关重要的几个门类，如硅藻、海带和甲藻。目前人们也对利用这些藻类实现工业用途，如生产生物柴油，有着浓厚的兴趣。然而，其组成物种的进化，尤其是叶绿体基因组的起源和辐射，仍然知之甚少。在这篇综述中，我们讨论了关于色藻界现存红藻衍生叶绿体谱系起源的当前理论，以及色藻界基因组中大量绿藻基因的近期发现可能产生的影响。我们认为，对此的最佳解释是，色藻界在历史上拥有一种神秘的绿藻内共生体，随后被红藻叶绿体所取代。我们思考了作用于古代色藻界谱系的不断变化的选择压力如何可能选择性地促进了绿藻和红藻的连续内共生，以及复杂的内共生历史是否促进了色藻界崛起至其当前在生态上的显著地位。
