Sesame phyllody associated with a 16SrI-B phytoplasma, a ‘Candidatus Phytoplasma asteris’-related strain, in Paraguay

ABSTRACT: Sesame (Sesamum indicum L.) plants exhibiting symptoms of phyllody disease were observed in commercial fields in Paraguay. The symptoms were indicative of infection by phytoplasmas. Thus, the present study investigated the association between affected plants and phytoplasma, which was later analyzed using molecular and phylogenetic methods. Total DNA was extracted from symptomatic and asymptomatic plants and used in nested PCR assays using primers R16SN910601/R16SN011119 and R16F2n/16R2. Amplified products of 1.2 Kb revealed the presence of phytoplasma in all diseased plants, and electron microscopy confirmed the presence of phytoplasmas within phloem vessels. Nucleotide sequences from sesame phytoplasma shared 99 % similarity with phytoplasmas belonging to group 16SrI. Computer-simulated RFLP indicated that the detected phytoplasma is representative of the 16SrI-B, therefore, a ‘Candidatus Phytoplasma asteris’-related strain. Phylogenetic analysis was in agreement with virtual RFLP. Our findings expand the current knowledge regarding distribution of representatives of the aster yellows group in a new agroecosystem and implicate sesame as a new host of 16SrI-B phytoplasma in Latin America.