Šeruga Musić Martina, Polak Bruno, Drčelić Marina, Pei Shen-Chian, Kuo Chih-Horng
Department of Biology, Faculty of Science, University of Zagreb, Zagreb, Croatia.
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, ROC.
Microb Genom. 2025 Apr;11(4). doi: 10.1099/mgen.0.001401.
Phytoplasmas (genus ' Phytoplasma') encompass a group of uncultivated bacteria affecting numerous plant species and causing significant damage in agriculture worldwide. They have a dual parasitic cycle, including colonization of both plant phloem and insect cells. Their genomes are small, diverse, repetitive, prone to rearrangements and harbour transposon-like elements known as potential mobile units (PMUs). In the Euro-Mediterranean region, '. P. solani' is an important species due to its broad range of plant hosts and insect vectors. To provide insights into the genomic diversity of this species, particularly the repertoire of putative effectors and PMUs, this study conducted genome sequencing and analyses of two . P. solani' strains originating from different plants and transmitted by different insects. Based on assembly, we obtained 19 contigs totalling 656 141 bp for strain STOL and 28 contigs totalling 707 036 bp for strain ST19. The prevalence of repetitive sequences and PMUs contributed to the fragmentation of these draft assemblies. The annotation identified 28 and 26 genes that encode putative secreted proteins in these two strains, respectively, including several homologues of previously characterized phytoplasma effectors. Our comparative analyses further identified species- and strain-specific genes. Frequently, genes that encode putative secreted proteins and effectors were found within PMU-like regions in both genomes. Moreover, strain STOL showed characteristics of a more reduced genome, having fewer PMU-like repetitive elements and genome rearrangements, while strain ST19 exhibited a higher level of sequence divergence in its PMU genes. The high levels of genomic diversity among '. P. solani' strains suggested rapid evolution of this species, which may contribute to its wide host range and adaptability potential. This study provides novel data on the diversification of '. P. solani' genomes. These results provide a foundation for future functional studies of putative effectors and their interactions with host targets, which could facilitate deciphering the pathogenicity strategies of this successful and versatile pathogen.
植原体（“植原体属”）是一类无法人工培养的细菌，会影响众多植物物种，并在全球农业领域造成重大损失。它们具有双重寄生周期，包括在植物韧皮部和昆虫细胞中定殖。它们的基因组小、多样、重复，易于重排，并且含有被称为潜在移动单元（PMU）的转座子样元件。在欧洲 - 地中海地区，“茄科植原体”是一个重要物种，因为它具有广泛的植物宿主和昆虫传播媒介。为了深入了解该物种的基因组多样性，特别是推定效应子和PMU的组成，本研究对源自不同植物并由不同昆虫传播的两个“茄科植原体”菌株进行了基因组测序和分析。基于组装，我们获得了STOL菌株的19个重叠群，总计656141 bp，以及ST19菌株的28个重叠群，总计707036 bp。重复序列和PMU的普遍存在导致了这些草图组装的碎片化。注释分别在这两个菌株中鉴定出28个和26个编码推定分泌蛋白的基因，包括几个先前已鉴定的植原体效应子的同源物。我们的比较分析进一步鉴定了物种和菌株特异性基因。通常，在两个基因组中类似PMU的区域内发现了编码推定分泌蛋白和效应子的基因。此外，STOL菌株显示出基因组更简化的特征，具有较少的类似PMU的重复元件和基因组重排，而ST19菌株在其PMU基因中表现出更高水平的序列差异。“茄科植原体”菌株之间高度的基因组多样性表明该物种进化迅速，这可能有助于其广泛的宿主范围和适应潜力。本研究提供了关于“茄科植原体”基因组多样化的新数据。这些结果为未来推定效应子的功能研究及其与宿主靶点的相互作用奠定了基础，这有助于破译这种成功且多面的病原体的致病策略。
