Phytoplasmas diversity and identification of new aster yellows subgroup (16SrI) associated with weed species in Argentina

Symptoms of phytoplasma infection were observed in different weed species, Bidens subalternans , Conyza bonariensis , Heterosperma ovatifolium and Conium maculatum , collected from diverse geographical regions in Argentina. To confirm the association of phytoplasma infection with symptomatic plants, PCR, RFLP and phylogenetic analyses based on 16S rRNA-encoding sequences were performed. In this work, we report the presence of phytoplasmas from group 16SrVII (subgroup 16VII-B) infecting C. bonariensis and B. subalternans and from group 16SrIII (subgroup 16SrIII-X) B. subalternans , H. ovatifolium , and C. maculatum . Phytoplasmas from the aster yellows group were detected infecting C. bonariensis and B. subalternans . Analysis of 16S rRNA-encoding genes revealed the presence of two distinct operons, rrnB (16SrI-B) and newly described rrnA , which is different from the reference RFLP patterns of all previously established 16SrI-subgroups. A single rp operon sequence analysis reveals the presence of simple infection and confirms a description of a novel subgroup. On the basis of these results we propose a designation of new subgroup 16SrI-(B/AJ) AJ ( rp -AJ). To our knowledge, this is the first report of phytoplasmas infecting Bidens subalternans ¸ Heterosperma ovatifolium and Conium maculatum .