Archivio Journal of Plant Pathology

Abstract:

An emerging soybean disease observed in Cuba was investigated in view of the possibility that a phytoplasmas could be involved in its aetiology. Thirty-five soybean plants showing symptoms of stunting, chlorosis, crinkle and aborted seed pods were collected in Las Tunas and Holguin provinces during 2013, and analysed by nested-PCR with primers targeting the 16S ribosomal DNA (16S rDNA). Phytoplasmas were detected in 83% of symptomatic soybean plants. Conventional and virtual RFLP analyses of 16S rDNA sequences revealed the presence of strains of ‘Candidatus Phytoplasma asteris’ (16SrI group). Phytoplasmas belonging to ribosomal subgroup 16SrI-B and two putative new ribosomal subgroups 16SrI-W and 16SrI-Y were identified. Phylogenetic analysis corroborated the RFLP analyses, in which the Cuban strains formed a clade with representative sequences of the 16SrI group. 16SrI-B was the most prevalent subgroup (45% of positive samples) and mixed infections of different subgroups were observed (10% of the positive samples). The partial 16S rDNA sequences of three strains showed 99% nucleotide identity to several GenBank sequences of group 16SrI phytoplasmas, including a phytoplasma associated with a soybean disease in Brazil. This is the first report of a phytoplasma belonging to the 16SrI subgroup occurring in soybean in Cuba.