Geographical and Temporal Diversity of 'Candidatus Phytoplasma solani' in Wine-Growing Regions in Slovenia and Austria

As the causal agent of the grapevine yellows disease Bois noir, 'Candidatus Phytoplasma solani' has a major economic impact on grapevines. To improve the control of Bois noir, it is critical to understand the very complex epidemiological cycles that involve the multiple Ca. P. solani host plants and insect vectors, of which Hyalesthes obsoletus is the most important. In the present study, multiple genotyping of the tuf, secY, stamp, and vmp1 genes was performed. This involved archived grapevine samples that were collected during an official survey of grapevine yellows throughout the wine-growing regions of Slovenia (from 2003 to 2016), plus samples from Austrian grapevines, stinging nettle, field bindweed, and insect samples (collected from 2012 to 2019). The data show that the tuf-b2 type of the tuf gene has been present in eastern Slovenia since at least 2003. The hypotheses that the occurrence of the haplotypes varies due to the geographical position of Slovenia on the Italian-Slovenian Karst divide and that the haplotypes are similar between Slovenian and Austrian Styria were confirmed. The data also show haplotype changes for host plants and H. obsoletus associated with 'Ca. P. solani,' which might be linked to new epidemiological cycles of this phytoplasma that involve not just new plant sources and new insect vectors, but also climate and land-use changes.

Automated summary

This study conducted multiple genotyping of the tuf, secY, stamp, and vmp1 genes of the causative agent of grapevine yellows disease, 'Candidatus Phytoplasma solani', and found that the tuf-b2 type of the tuf gene has been present in eastern Slovenia since at least 2003. The hypotheses that the occurrence of different haplotypes varies due to geographical position and that the haplotypes are similar between Slovenia and Austrian Styria were confirmed. The data also indicate changes in haplotypes related to host plants and insect vectors associated with 'Ca. P. solani', possibly due to new epidemiological cycles and environmental changes.