Molecular identification of ‘Candidatus phytoplasma species’ associated with little leaf disease of Ziziphus oenopolia and Solanum melongena from Madhya Pradesh, India

Several plant species are being grown in Madhya Pradesh as cereal, oil crops, vegetables and ornamental plants. In India, recent evidence showed that phytoplasma causes diseases in several plant species and results in a serious threat to economically important plants. Phytoplasmas are intracellular obligate prokaryotes which lack cell wall, have small genome and are mainly transmitted by leafhoppers. Severe little leaf diseases were observed in Oct 2024 on Ziziphus oenoplia and Solanum melongena with significant disease incidence in Bhopal and Ganjbasoda, Vidisha. Phytoplasma was detected from symptomatic leaf samples by polymerase chain reaction using phytoplasma 16S rRNA gene specific primers. The positive amplicons of the phytoplasma 16S rRNA (1.2 kb) were sequenced and sequence data was submitted in GenBank (PQ725601 and PQ725602). The sequence analysis of 16S rRNA gene of Z. oenopolia (PQ725601) revealed the highest 99% sequence identities and a close relationship with several isolates of ‘Candidatus Phytoplasma balanitae’. The under study phytoplasma isolate of S. melongena (PQ725602) also showed highest 96% sequence identities and shared distant phylogenetic relationships with isolates of ‘Ca. P. trifolii’ and ‘Ca. P. fraxini’ groups. Based on the highest sequence identities and close phylogenetic relationships of Z. oenoplia isolate was identified as an isolate of ‘Ca. P. balanitae’ (16SrV). The S. melongena under study phytoplasma isolate also showed less than 97.55% sequence similarities and distinct phylogenetic relationships were identified as isolates of ‘Ca. P. trifolii’ (16SrVI group) and Ca. P. fraxini’ (16SrVII group). Based on less than 97.55% sequence similarity defined for species demarcation criteria by IRPCM 2004 and distinct phylogenetic relationships isolate under study was considered as a new ‘Ca. Phytoplasma species in S. melongena. However the BLL phytoplasma under study was identified as a new ‘Ca. Phytoplasma’ species in S. melongena in the first time from Madhya Pradesh as well as India.