Gould Sven B, Waller Ross F, McFadden Geoffrey I
School of Botany, University of Melbourne, Parkville VIC-3010, Australia.
Annu Rev Plant Biol. 2008;59:491-517. doi: 10.1146/annurev.arplant.59.032607.092915.
The ancestors of modern cyanobacteria invented O(2)-generating photosynthesis some 3.6 billion years ago. The conversion of water and CO(2) into energy-rich sugars and O(2) slowly transformed the planet, eventually creating the biosphere as we know it today. Eukaryotes didn't invent photosynthesis; they co-opted it from prokaryotes by engulfing and stably integrating a photoautotrophic prokaryote in a process known as primary endosymbiosis. After approximately a billion of years of coevolution, the eukaryotic host and its endosymbiont have achieved an extraordinary level of integration and have spawned a bewildering array of primary producers that now underpin life on land and in the water. No partnership has been more important to life on earth. Secondary endosymbioses have created additional autotrophic eukaryotic lineages that include key organisms in the marine environment. Some of these organisms have subsequently reverted to heterotrophic lifestyles, becoming significant pathogens, microscopic predators, and consumers. We review the origins, integration, and functions of the different plastid types with special emphasis on their biochemical abilities, transfer of genes to the host, and the back supply of proteins to the endosymbiont.
现代蓝藻的祖先大约在36亿年前发明了产生氧气的光合作用。水和二氧化碳转化为富含能量的糖类和氧气的过程，慢慢地改变了地球，最终形成了我们今天所知的生物圈。真核生物并没有发明光合作用；它们通过吞噬并稳定整合一种光合自养原核生物，在一个被称为初级内共生的过程中从原核生物那里获得了光合作用。经过大约十亿年的共同进化，真核宿主及其内共生体实现了非凡程度的整合，并产生了一系列令人眼花缭乱的初级生产者，这些生产者如今支撑着陆地和水中的生命。没有哪种共生关系对地球上的生命比这更重要。次级内共生产生了更多的自养真核生物谱系，其中包括海洋环境中的关键生物。其中一些生物后来又恢复为异养生活方式，成为重要的病原体、微观捕食者和消费者。我们回顾了不同质体类型的起源、整合和功能，特别强调了它们的生化能力、基因向宿主的转移以及蛋白质向内共生体的反向供应。
