Data from: Functional relationship between a dinoflagellate host and its diatom endosymbiont

While we know much about the evolutionary patterns of endosymbiotic organelle origins, we know less about how the actual process unfolded within each system. This is partly due to the massive changes endosymbiosis appears to trigger, and partly because most organelles evolved in the distant past. The dinotoms are dinoflagellates with diatom endosymbionts, and they represent a relatively recent but nevertheless obligate endosymbiotic association. We have carried out deep sequencing of both the host and endosymbiont transcriptomes from two dinotoms, Durinskia baltica and Glenodinium foliaceum, to examine how the nucleocytosolic compartments have functionally integrated. This analysis showed little or no functional reduction in either the endosymbiont or host, and no evidence for genetic integration. Rather, host and endosymbiont seem to be bound to each other via metabolites, such as photosynthate exported from the endosymbiont to the host as indicated by the presence of plastidic phosphate translocators in the host transcriptome. The host is able to synthesize starch, using plant-specific starch synthases, as a way to store imported photosynthate.尽管学界对细胞器内共生起源（endosymbiotic organelle origins）的演化模式已有较为充分的认识，但针对各共生体系中实际的过程演进细节，我们的了解仍较为有限。这一方面源于内共生作用似乎会触发大规模的细胞重塑，另一方面则是因为绝大多数细胞器均起源于遥远的地质历史时期。硅藻内共生型甲藻（dinotoms）是一类携带有硅藻内共生体的甲藻（dinoflagellates），它们代表了一种相对晚近但却专性的内共生关联。我们针对两种硅藻内共生型甲藻——波罗的海双甲藻（Durinskia baltica）与叶状沟鞭藻（Glenodinium foliaceum）——的宿主及内共生体转录组开展了深度测序，以此解析核胞质区室的功能整合机制。分析结果表明，无论是内共生体还是宿主，均未出现明显的功能退化，也未找到遗传整合的相关证据。与之相反，宿主与内共生体似乎通过代谢产物实现相互绑定：宿主转录组中检测到质体磷酸转运蛋白（plastidic phosphate translocators），这提示内共生体可将光合产物输出至宿主；宿主能够借助植物特异性淀粉合酶（starch synthases）合成淀粉，以此储存摄入的光合产物。