Phloem limited bacteria in potato with purple top disease and in Bactericera cockerelli in Ecuador

Molecular identification of the pathogens involved in the potato purple top disease in Ecuador has been shown an unspected diversity in both plants and psyllid vectors. A series of field surveys in the main potato growing areas of the country along with phytoplasma identification on the 16S rRNA gene by PCR, RFLP and sequencing were carried out in 2022. Phytoplasmas belonging to groups 16SrII (‘Candidatus Phytoplasma aurantifolia=citri’) and 16SrV (‘Ca. P. ulmi’) were found in potato samples collected in two of the surveyed locations. Moveover, insects collected from fields were confirmed to be specimens of Bactericera cockerelli, Central haplotype by the analyses of the mitochondrial CO1 gene. ‘Ca. Liberibacter solanacearum’ haplotype A was identified in both potato and psyllids samples by amplification and sequencing of the 16S rRNA gene, the 50S rplJ and rplL ribosomal protein genes, and the 16S/23S intergenic spacer region. The phytoplasmas in 16SrV group were never reported in Ecuador, while in the ‘Ca. L. solanacearum’ haplotype a SNP in the 16S/23S ISR sequences of the samples compared to the available sequences was identified.