Prevalence and molecular identification of ‘Candidatus Phytoplasma asteris’ strains in okra crops across three Indian states.

Besides viral diseases, phytoplasma-associated diseases pose a significant threat to okra cultivation in India. During 2022-2025 seasons, okra plants exhibiting characteristic phytoplasma symptoms such as little leaf, shoot proliferation, bud proliferation and bunchy crown were observed in Kerala, New Delhi and Tripura states of India. Molecular detection using phytoplasma-specific primers P1/Tint and R16F2n/R16R2 amplified DNA fragments of about 1.25 kb of the 16S rRNA gene from symptomatic okra leaf samples, while asymptomatic samples showed no amplifications. Pairwise sequence analysis of the 16S rRNA gene revealed almost 100% identity among the okra phytoplasma strains in the study and ‘Candidatus Phytoplasma asteris’ strains. Phylogenetic analysis further clustered these okra phytoplasma strains with ‘Ca. P. asteris’ strains. In silico RFLP analysis employing 17 restriction endonucleases confirmed the affiliation of the okra phytoplasma strains within the 16SrI-B subgroup, with a similarity coefficient of 1.00. Although the ‘Ca. P. asteris’ has been reported earlier in India, the present study highlights the prevalence and importance of ‘Ca. P. asteris’ strains occurrence in okra crops across three Indian states, underscoring their epidemiological importance.