Molecular characterization of Candidatus Phytoplasma australasiaticum strain causing mixed infection with chilli leaf curl virus (Begomovirus chillicapsici) on Capsicum annuum in India

Chilli ( Capsicum annuum L.) cultivation is severely threatened by viral and phytoplasma pathogens, leading to significant yield losses. During a field survey at Tamil Nadu Agricultural University, Coimbatore, India, chilli plants showing typical begomovirus symptoms (upward leaf curling, crinkling) and phytoplasma-like symptoms (witches’ broom) were observed. Molecular assays confirmed the presence of Chilli leaf curl virus ( Begomovirus chillicapsici - ChiLCV) and ‘Candidatus Phytoplasma australasiaticum ’ in the tested samples. Sequence and phylogenetic analyses revealed close similarity of ChiLCV with isolates from Karnataka and Andhra Pradesh, while the phytoplasma clustered with the 16SrII-D subgroup. Virtual RFLP alaysis also further validated the subgroup classification. The findings of present study revealed the co-infection of Ca . P. australasiaticum and ChiLCV in chilli. The study underscores the emerging complexity of pathogen interactions and highlights the importance of molecular diagnostics in identifying mixed infections.