Detection and molecular characterization of two genetically distinct phytoplasmas associated with mungbean seed pod abortion in Iran

Abstract

New symptoms including aborted seed pods disease were observed on mungbean (Vigna radiata) plants in the most important growing areas in Iran that was similar to symptoms of phytoplasma disease previously reported from Australia. Thirty samples were collected from symptomatic and non-symptomatic plants, followed by PCR amplification, DNA sequencing, RFLP and phylogenetic analysis of 16S ribosomal RNA gene to detect and identify possible associated phytoplasmas. Results indicated that two different phytoplasmas, related to ‘Candidatus Phytoplasma trifolii’ and ‘Candidatus Phytoplasma aurantifolia’, were associated with different symptomatic plants samples from the same field, mixed infection was not observed in these samples. The sequence analysis results indicated that the nucleotide sequences from mungbean isolates 47 (MT674290), 7 (MT674291) and 32 (MT674292) had 98.8% sequence identity to ‘Candidatus Phytoplasma aurantifolia’ isolate TBBP-H1 (Acc. No: MN565885), while isolates 80 (MT674293) and 25 (MT674294) had 99.8% sequence identity similar to ‘Candidatus Phytoplasma trifolii’ (MF092789). In silico RFLP and phylogenetic analyse of mungbean seed pod abortion (MubSpa) phytoplasma indicated that the associated phytoplasmas belonged to phytoplasmas of subgroups 16SrVI-A and 16SrII-D. To the best of our knowledge, this is the first report of association ‘Ca. P. trifolii’ and ‘Ca. P. aurantifolia’ strains infecting mungbean plants in Iran.