The Asian citrus psyllid Diaphorina citri (Insecta: Hemiptera: Psylloidea), a serious pest of citrus species worldwide, harbors vertically transmitted intracellular mutualists, Candidatus Profftella armatura (Profftella_DC, Gammaproteobacteria: Burkholderiales) and Candidatus Carsonella ruddii (Carsonella_DC, Gammaproteobacteria: Oceanospirillales). Whereas Carsonella_DC is a typical nutritional symbiont, Profftella_DC is a unique defensive symbiont with organelle-like features including intracellular localization within the host, perfect infection in host populations, vertical transmission over evolutionary time, and drastic genome reduction down to much less than 1 Mb. Large parts of the 460 kb genome of Profftella_DC are devoted to genes for synthesizing a polyketide toxin; diaphorin. To better understand the evolution of this unusual symbiont, the present study analyzed the genome of Profftella_Dco, a sister lineage to Profftella_DC, using Diaphorina cf. continua, a host psyllid congeneric with D. citri. The genome of co-residing Carsonella (Carsonella_Dco) was also analyzed. The analysis revealed nearly perfect synteny conservation in these genomes with their counterparts from D. citri. The substitution rate analysis further demonstrated genomic stability of Profftella which is comparable to that of Carsonella. Profftella_Dco and Profftella_DC shared all genes for the biosynthesis of diaphorin, hemolysin, riboflavin, biotin, and carotenoids, underlining multiple roles of Profftella, which may contribute to stabilizing symbiotic relationships with the host. However, acyl carrier proteins (ACPs) were extensively amplified in polyketide synthases DipP and DipT for diaphorin synthesis in Profftella_Dco. This level of ACP augmentation, unprecedented in modular polyketide synthases of any known organism, is not thought to influence the polyketide structure but may improve the synthesis efficiency.

中文翻译：

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比较基因组学强调 Profftella 的多种作用，木虱的专性共生体：提供毒素、维生素和类胡萝卜素。

亚洲柑橘木虱Diaphorina citri（昆虫纲：半翅目：Psylloidea）是世界范围内柑橘属的一种严重害虫，具有垂直传播的细胞内共生体，Candidatus Profftella armatura ( Profftella _DC, Gammaproteobacteria: Burkholderiales) 和Candidatus Carsonella ruddii ( Carsonella ruddii, Carsonella ruddii) ）。而Carsonella _DC是一种典型的营养共生，Profftella_DC 是一种独特的防御性共生体，具有细胞器样特征，包括宿主内的细胞内定位、宿主种群的完美感染、进化时间内的垂直传播以及基因组急剧减少至远小于 1 Mb。Profftella _DC的 460 kb 基因组中有很大一部分专门用于合成聚酮毒素的基因；胆黄素。为了更好地理解这个不寻常的共生体的进化，本研究分析的基因组Profftella _Dco，一个妹妹谱系Profftella _DC，使用Diaphorina参见 continua，一种与D. citri同源的寄主木虱。共存卡森氏菌的基因组（还分析了卡森氏菌_Dco)。该分析揭示了这些基因组与来自柑橘属植物的对应物几乎完美的同线性保守性。置换率分析进一步证实的基因组稳定性Profftella其比得上Carsonella。Profftella _Dco 和Profftella _DC 共享所有用于合成胆黄素、溶血素、核黄素、生物素和类胡萝卜素的基因，强调了Profftella 的多种作用，这可能有助于稳定与宿主的共生关系。然而，酰基载体蛋白 (ACPs) 在聚酮化合物合成酶 DipP 和 DipT 中被广泛扩增，用于合成胆黄素。Proftella _Dco。这种 ACP 增强水平在任何已知生物的模块化聚酮化合物合酶中都是前所未有的，被认为不会影响聚酮化合物结构，但可以提高合成效率。