Emerging incidence of tomato big bud disease associated with a 16srii-d phytoplasma in Andhra Pradesh and odisha states of India

Tomato is an important vegetable crop and India ranks second in the area and production of tomatoes worldwide. During field surveys in the Ananthapuramu district of Andhra Pradesh and Khordha district of Odisha in 20202021, the presence of big bud and phyllody symptoms was recorded in commercially cultivated tomato varieties. The incidence ranged from 2.5 to 4.16%. Amplicons of about 1.2 kb were consistently amplified from the DNA extracted from symptomatic bud tissues of all the symptomatic plants and of the positive control using 16S rRNA gene-specific primer pairs P1/P7 and R16F2n/R16R2 in a nested PCR assay. However, no amplification was achieved with any of the non-symptomatic samples. The phylogenetic analysis of the 16S rDNA sequence of the detected phytoplasma strains from both locations indicated the clustering of these strains with ‘Candidatus Phytoplasma australasia’. The virtual RFLP analysis indicated that the phytoplasma strains infecting tomato belonged to 16SrII-D subgroup. These phytoplasmas were detected in tomatoes showing big bud disease from other states of India. This report further confirmed the wider spread and incidence of phytoplasma diseases in new tomato growing areas of the country where they are causing serious yield losses.