Genetic Diversity in Phytoplasmas from X-Disease Group Based in Analysis of and Genes.

Phytoplasmas of the X-disease group (16SrIII) are economically significant pathogens in South America, causing severe crop losses. Traditional classification based on the 16S rRNA gene has limitations in resolving closely related strains, prompting the exploration of alternative markers. This study focuses on the immunodominant membrane proteins imp and idpA, which exhibit high variability and play crucial roles in host-pathogen interactions. Through molecular characterization of and genes in 16SrIII subgroups, we identified significant genetic diversity and distinct evolutionary pressures. The gene, under positive selection, showed high variability in its hydrophilic extracellular domain, suggesting adaptation to host immune responses. In contrast, exhibited strong negative selection, indicating functional conservation. Phylogenetic analyses revealed that and provide higher resolution than the 16S rRNA gene, enabling finer differentiation within subgroups. These findings highlight the potential of and as complementary markers for phytoplasma classification and diagnostics.