Phytopathogenic Mollicutes

Fenugreek is a self-pollinating leafy vegetable and spice crop, native to Indian subcontinent and the Eastern Mediterranean region. Symptoms of little leaf and witches’ broom (FLL-WB) were noticed in several fenugreek germplasm accessions in different experimental fields of ICAR-NBPGR Regional Station, Jodhpur; ICAR-Central Arid Zone Research Institute, Jodhpur and Agricultural University Jodhpur, Rajasthan India during January 2022. The incidence of the disease varied from 1 to 21% in the different fenugreek germplasm collections. Phytoplasma presence was confirmed in 146 fenugreek symptomatic germplasm accessions by employing phytoplasma primer pairs P1/P7 and R16F2/r16R2 and secA for-1/secA for-3. Pairwise sequence identity and phylogeny of 16S rRNA and secA gene sequences of FLL-WB strains in the study indicated the presence of ‘Candidatus Phytoplasma asteris’. Strains of this phytoplasma were identified in the leafhoppers Orosius albicinctus and Empoasca spp., collected from fenugreek fields along with horsegram plant (Macrotyloma uniflorum), and weeds (Phyllanthus niruri and Parthenium hysterophorus) growing in and nearby fenugreek fields. Phylogeny analysis of 16S rRNA gene and secA genes sequences and virtual RFLP analysis of 16S rRNA gene sequences further classified the fenugreek, horsegram, weeds and leafhoppers phytoplasmas as ‘Ca. P. asteris’ (16SrI-B subgroup). Out of 170 fenugreek genotypes evaluated in open field screening, 146 tested positive for ‘Ca. P. asteris’ and 24 did not show symptoms in any of the replications and also tested negative to phytoplasma presence. The phytoplasma free genotypes identified in the present study can be further utilized as pre-breeding materials to develop fenugreek resistant varieties to phytoplasma infection.