Identification of a Conserved Core Genome with Group-Specific Genes from Comparative Genomics of Ten Different Candidatus Phytoplasma Strains

Plant pathogenic phytoplasmas can infect hundreds of plant species and lead to enormous economic loss. To understand the interactions between phytoplasmas and their hosts, genome sequencing plays an important role. To date, ten phytoplasma genomes from five phylogenetic groups have been released. A comparative genomics analysis showed 170 common conserved genes existing in these ten genomes. Genes involved in translation, ribosomal structure and biogenesis (75 genes) are the largest proportion. Interestingly, the predicted secreted proteins were not found in our core set, suggesting that these genes were diverse. In addition, a highly stringent strategy was taken to mine the group-specific genes among the five groups. Although the largest part was the hypothetical proteins, some putative secreted proteins (potential effectors) were identified. TENGU was selected to be one of the 16SrI group-specific genes. This may partly account for the diverse pathogenicity in different 16Sr groups. In addition, our results revealed that Amp and Imp had great potentials of being group specific. Above all, based on the conserved genes, our results provide new insights for the phytoplasma genome assembly, identification and functional genomics.