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Detection and identification of two phytoplasma subgroups associated with strawberry phyllody and red leaf disease in Chile

Weier Cui: University of Chile

<div>Strawberry (<em>Fragaria</em> x <em>ananassa</em> Duch.) production plays an important part in Chile’s agriculture, serving both domestic consumption and export. Since the year of 2015, strawberry plants with symptoms of fruit phyllody, achenes’ hypertrophy and leaf reddening have been identified in individual surveys, leading to our first report of phytoplasma infection in Chilean strawberry. In recent surveys of four individual orchards in Bio-bio and Araucanía regions of Chile, samples were collected from symptomatic plants and genomic DNA was extracted. Three genomic regions corresponding to the 16SrRNA, elongation factor Tu (<em>tuf</em>) and large ribosomal subunit protein <em>12p</em> genes were amplified by nested PCR. Each amplification product was cloned into the pGEM-T vector and multiple colonies were selected for sequencing to discriminate potentially multiple infections. Sequences alignments, phylogeny construction and <em>in silico</em> RFLP revealed two different phytoplasmas. One belongs to our previously-reported ribosomal subgroup 16SrXIII-F (100% of identity), whereas the other isolate lies outside all the eight known subgroups of 16SrXIII group (similarity coefficient < 0.91). Our research shows widespread phytoplasma infection on Chilean strawberry crops, which calls for attention from private producers as well as seedling suppliers. We also report the detection and identification of a novel 16SrXIII subgroup of phytoplasma associated with strawberry phyllody and red leaf disease.</div>