Detection and identification of 16SrXIII-F and a novel 16SrXIII phytoplasma subgroups associated with strawberry phyllody in Chile

Since the year 2015, strawberry plants with symptoms of phyllody, achenes' hypertrophy and leaf reddening have been observed in several fields in various regions of Chile. In recent surveys on five individual fields in Biobio and Araucania regions, samples were collected from symptomatic plants and DNA was extracted. Two genomic regions corresponding to the 16S rRNA and tuf genes were amplified by nested PCR using phytoplasma universal primers. Three individual clones of each amplicon from each sample were then sequenced. The RFLP analyses of the 16S rDNA amplicons showed that all of the symptomatic plants were infected by phytoplasmas enclosed in the 16SrXIII group. This result was confirmed by phylogenetic analysis with tuf amplicons. RFLP similarity coefficients indicated the presence of two phytoplasmas, one belonging to the 16SrXIII-F subgroup, while the other resulting not enclosed in any of the described subgroups and therefore it was assigned to the newly proposed 16SrXIII-K subgroup.