Comparative Genome Analysis of 16SrXII-A ‘Candidatus Phytoplasma solani’ POT Transmitted by Hyalesthes obsoletus

TL;DR

This paper presents the complete genome of a German stolbur phytoplasma strain, offering insights into its evolution and potential impact on crops.

Contribution

The first reported genome of an H. obsoletus-transmissible 16SrXII-A phytoplasma from Germany, revealing unique genetic features and evolutionary divergence.

Findings

The POT genome shares highest nucleotide identity with Italian bindweed-associated genomes and shows strong synteny with the c5 strain.

The genome includes unique collagen-like proteins that may contribute to virulence and lacks organized pathogenicity islands.

Phylogenetic analyses reveal heterogeneity within the stolbur group and provide a framework for improved diagnostics and breeding assessments.

Abstract

‘Candidatus Phytoplasma solani’ of the 16SrXII group is an emerging vector-borne pathogen in European crop production. The cixiid planthopper Hyalesthes obsoletus transmits 16SrXII-A stolbur phytoplasmas that are associated with diseases in grapevine, potato, and various weeds. While 16SrXII-P genomes transmitted by Pentastiridius leporinus are available, no genome of an H. obsoletus-transmissible 16SrXII-A phytoplasma has been reported from Germany. Here, we present insights into the phylogenetic position and pathogen–host interactions through the functional reconstruction of the complete 832,614 bp genome of the H. obsoletus transmissible ‘Ca. P. solani’ 16SrXII-A strain POT from a potato field. Phylogenetic analyses highlight the heterogeneity within the stolbur group using whole-genome alignment and a BUSCO-based core gene analysis approach. The POT chromosome shares highest average nucleotide identity with Italian bindweed-associated genomes and displays strong synteny with the c5 strain. Consistent with the typical phytoplasma architecture, the POT genome combines mobile-element-driven instability with a conserved core metabolism. Virulence factors include transposon-linked effectors but lack pathogenicity island organisation. POT further differs from other 16SrXII-group phytoplasmas through unique collagen-like proteins that could contribute to virulence. These findings provide a robust genomic framework that improves diagnostics, enables strain-level resolution and supports the assessment of breeding materials under stolbur phytoplasma pressure, thereby refining our understanding of stolbur phytoplasma diversity and highlighting the evolutionary divergence within the 16SrXII subgroup.

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