Distribution and characterization of phytoplasmas infecting flower crops with diverse symptoms in Andhra Pradesh State, India

During field surveys in 2022-23, phytoplasma diseases were a significant threat to the major flower crops of Andhra Pradesh, India, causing substantial economic losses. In this study, symptoms of phytoplasma were observed in three predominant flower crops of Andhra Pradesh: marigold, crossandra, and jasmine. Samples were collected from major flower growing areas of the state and subjected to PCR assays using universal P1/P7, R16F2n/R2 primers for amplification of the 16 S rRNA gene and gene-specific SecAfor2/Rev3 primers for amplification of a part of the secA gene. The 16 S rRNA gene sequence identity percentage based on Blast and in silico RFLP analysis of PCR-amplified phytoplasma 16 S rDNA was used to identify and classify them into sub-groups. The restriction profiles generated by digestion with 17 restriction endonucleases, showed that phytoplasma strains infecting marigold were highly uniform with members of ‘Candidatus Phytoplasma asteris’ (16SrI-B) and the phytoplasma strains infecting crossandra and jasmine were uniform with members of ‘Candidatus Phytoplasma australasiaticum’ (16SrII-D) subgroup. These phytoplasma strains were not previously reported to infect any flower crops in the state. Marigold, crossandra and jasmine are therefore considered new hosts for the 16SrI and 16SrII group phytoplasmas in Andhra Pradesh. In addition, this study also identified some new disease symptoms in marigold plants in addition to previously known ones.