A new phytoplasma strain in group 16SrV associated with witches’ broom disease of ziziphus oenoplia in Karnataka, India

Ziziphus oenoplia, also known as jackal jujube or small fruited jujube is a spiny, evergreen small tropical fruit tree. During a survey in October-November 2019, the jujube trees exhibited severe witches’ broom symptoms, therefore, an investigation was carried out, to verify the presence of phytoplasmas in these symptomatic plants. Total DNA was extracted from leaves of jujube plants using a CTAB method and a PCR assay was performed using 16S rRNA gene specific primer pairs P1/P7 and 3Far/3Rev. Amplicons of about 1.3 kb were consistently amplified from all the symptomatic plant samples in nested PCR assays, while, no amplification was observed in non-symptomatic samples. The phylogenetic analysis of 16Sr DNA sequence of the detected phytoplasma strain indicates its clustering with ‘Candidatus Phytoplasma balanitae’ strains and also its close relatedness to 16SrV-F subgroup phytoplasmas. The virtual RFLP analysis of the 16Sr DNA sequence revealed that it could tentatively be classified into a novel phytoplasma subgroup since its AluI restriction profile was unique to earlier reported subgroup strains in 16SrV group.