Sequence analysis of coat protein and molecular profiling of sunflower necrosis virus (SNV) strains from Indian subcontinent

Sunflower is one of the leading edible oilseed crops of the world and is an important oil-producing crop of India. The sunflower necrosis disease caused by sunflower necrosis virus (SNV) has become a major hurdle for cultivation of sunflower in India. However, there is lack of genetic information and standard methods for detection and identification of the SNV. To address this issue, we have developed an application using coat protein (CP) to perform molecular profiling of SNV strains. The nucleic acid and amino acid sequence analysis of CP of SNV strains collected from different regions of Maharashtra and Karnataka showed high percent homology (96.89-98.87%). However, 3D structural analysis generated eleven distinct groups of SNV strains. Comparative bioinformatic analyses of nucleic acid and amino acid sequences with different genera of positive stranded (+) ssRNA viruses established their phylogentic relationship with similar to 25 (+) ssRNA viruses viz., Ilarvirus, Bromovirus, Cucumovirus, Alfamovirus, Comovirus, Nepovirus, Sequivirus, Potyvirus and Closterovirus. Additionally, the phylogenetic analysis revealed three distinct clusters, wherein major cluster I comprised SNV strains and Tobacco streak virus together showing 99% sequence homology and established closer phylogenetic relationship among all member viruses.