Reef‐building corals live in a mutualistic relationship with photosynthetic algae (family Symbiodiniaceae) that usually provide most of the energy required by the coral host. This relationship is sensitive to temperature stress; as little as a 1°C increase often leads to the collapse of the association. This sensitivity has led to an interest in the potential of more stress‐tolerant algae to supplement or substitute for the normal Symbiodiniaceae mutualists. In this respect, the apicomplexan‐like microalga Chromera is of particular interest due to its greater temperature tolerance. We generated a de novo transcriptome for a Chromera strain isolated from a GBR coral (‘GBR Chromera’) and compared with those of the reference strain of Chromera (‘Sydney Chromera’), and to those of Symbiodiniaceae (Fugacium kawagutii, Cladocopium goreaui and Breviolum minutum), as well as the apicomplexan parasite, Plasmodium falciparum. In contrast to the high sequence divergence amongst representatives of different genera within the family Symbiodiniaceae, the two Chromera strains featured low sequence divergence at orthologous genes, implying that they are likely to be conspecifics. Although KEGG categories provide few criteria by which true coral mutualists might be identified, they do supply a molecular rationalization that explains the ecological dominance of Cladocopium spp. amongst Indo‐Pacific reef corals. The presence of HSP20 genes may contribute to the high thermal tolerance of Chromera.

中文翻译：

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铬和共生植物的比较转录组学分析。

造礁珊瑚与光合藻（Symbiodiniaceae科）生活在相互关系中，后者通常提供珊瑚宿主所需的大部分能量。这种关系对温度应力敏感。低至1°C的升高通常会导致关联崩溃。这种敏感性引起了人们对更耐胁迫的藻类的潜力的兴趣，以补充或替代正常的共生植物。在这方面，类似apicomplexan的微藻Chromera因其较高的温度耐受性而特别受关注。我们为从GBR珊瑚（'GBR Chromera'）分离的Chromera菌株生成了一个从头转录组，并将其与参考菌株Chromera（'Sydney Chromera '），以及共生二科（Fugacium kawagutii，Cladocopium goreaui和Breviolum minutum），以及蚜虫寄生虫，恶性疟原虫（Plasmodium falciparum）。与共生菌科中不同属的代表之间的高序列差异相反，这两种Chromera菌株在直系同源基因上具有低序列差异，这表明它们很可能是同种的。尽管KEGG类别提供的标准很少，无法确定真正的珊瑚互助者，但它们的确提供了分子合理性，可以解释枝ado科的生态优势。spp。在印度太平洋珊瑚礁中。HSP20基因的存在可能导致的高耐热性Chromera。