Thompson Sarah, Wang Jinhui, Schott Thomas, Nissinen Riitta, Haapalainen Minna
The New Zealand Institute for Plant and Food Research Limited, Lincoln, New Zealand.
College of Plant Protection, Hebei Agricultural University, Lekai South Street 2596, Baoding, 071001, Hebei, China.
Curr Microbiol. 2025 Feb 20;82(4):145. doi: 10.1007/s00284-025-04119-y.
Carrot psyllid Trioza apicalis is a serious pest of cultivated carrot and also a vector of the plant pathogen 'Candidatus Liberibacter solanacearum' (Lso). To find out whether T. apicalis harbours other species of bacteria that might affect the Lso infection rate, the bacterial communities and metagenome in T. apicalis were studied. Lso haplotype C was detected in a third of the psyllids sampled, at different relative amounts. Surprisingly, T. apicalis was found to harbour only one secondary endosymbiont, a previously unknown species of gamma proteobacterium endosymbiont (Gpe), beside the primary endosymbiont 'Candidatus Carsonella ruddii' (CCr). The relative abundancies of these two endosymbionts were approximately equal. The genomes of CCr, Gpe and Lso were assembled from a T. apicalis metagenome sample. Based on the 16S rRNA gene, the closest relative of Gpe of T. apicalis could be a secondary endosymbiont of Trioza magnoliae. The 253.171 kb Gpe genome contains all the tRNA and rRNA genes and most of the protein-coding genes required for DNA replication, transcription and translation, but it lacks most of the genes for amino acid biosynthesis. Gpe has no genes encoding cell wall peptidoglycan synthesis, suggesting it has no cell wall, and could thus live as an intracellular endosymbiont. Like the CCr of other psyllids, CCr of T. apicalis retains a broad amino acid biosynthetic capacity, whilst lacking many genes required for DNA replication and repair and for transcription and translation. These findings suggest that these two endosymbionts of T. apicalis are complementary in their biosynthetic capabilities.
胡萝卜木虱Trioza apicalis是栽培胡萝卜的一种严重害虫，也是植物病原体“Ca. Liberibacter solanacearum”（Lso）的传播媒介。为了弄清楚T. apicalis是否携带其他可能影响Lso感染率的细菌物种，对T. apicalis中的细菌群落和宏基因组进行了研究。在三分之一的抽样木虱中检测到了Lso单倍型C，其相对含量不同。令人惊讶的是，除了初级内共生菌“Ca. Carsonella ruddii”（CCr）外，T. apicalis仅携带一种次级内共生菌，即一种先前未知的γ-变形菌内共生菌（Gpe）。这两种内共生菌的相对丰度大致相等。CCr、Gpe和Lso的基因组是从T. apicalis宏基因组样本中组装出来的。基于16S rRNA基因，T. apicalis的Gpe最接近的亲缘种可能是木兰三木虱的一种次级内共生菌。253.171 kb的Gpe基因组包含了所有的tRNA和rRNA基因以及DNA复制、转录和翻译所需的大部分蛋白质编码基因，但缺乏大多数氨基酸生物合成基因。Gpe没有编码细胞壁肽聚糖合成的基因，这表明它没有细胞壁，因此可以作为细胞内共生菌生存。与其他木虱的CCr一样，T. apicalis的CCr保留了广泛的氨基酸生物合成能力，但缺乏DNA复制和修复以及转录和翻译所需的许多基因。这些发现表明，T. apicalis的这两种内共生菌在生物合成能力上是互补的。
