Confirmation of the association of an aster yellows phytoplasma with flat stem and witches’ broom disease of Hibiscus cannabinus in the North East Region of India.

Hibiscus cannabinus also known as “kenaf” is a valuable fiber and medicinal plant growing in tropical and temperate areas of the world. During October 2019, symptoms of flat stem and witches’ broom were observed on 12% of the plants grown in the Agriculture College campus of Lembucherra, Tripura state of India. Samples from four symptomatic and two symptomless plants were subjected to DNA extraction and used as template in nested PCR assays with universal phytoplasma 16S rRNA gene primers. Amplification of about 1.25 kb product was obtained only from symptom-bearing H. cannabinus plants, but not from the asymptomatic ones. These PCR products were purified, cloned and sequenced. The R16F2n/R16R2 gene sequences of the identified phytoplasma strains showed 99.2-100% sequence identity with ‘Candidatus Phytoplasma asteris’ strains also supported by phylogenetic analyses. The virtual RFLP profiles of these phytoplasma strains were identical to each other and to those enclosed in the 16SrI-B subgroup with a similarity coefficient of 1.00. This is the first report of the association of ‘Ca. P. asteris’ with a “kenaf” flat stem and witches’ broom disease in the world.