Characterization and evolutionary analysis of Cucumber mosaic virus isolate infecting Salvia sclarea in India

Cucumber mosaic virus (CMV) is one of the most widespread viruses that infects a large number of cultivated crops worldwide and causes severe losses. Besides vegetables and ornamental crops, it is also spreading on medicinal and aromatic plants (MAPs) at an alarming rate. Natural occurrence of green mosaic, leaf curling, necrosis, and distortion were observed on the leaves of Salvia sclarea in the experimental field of CSIR-CIMAP, Lucknow, India. Mechanical transmission assay, morphological features, CP gene, and RNA3-based genomic characterization revealed the association of a new CMV isolate with the present disease. Virus is mechanically sap transmissible to the test plants. Transmission electron microscopy showed the presence of isodiametric particles of ~ 28 nm in diameter. Phylogenetic studies revealed that RNA3 (~ 2.2 kb) belongs to the subgroup IA of CMV. Multiple sequence alignment of amino acid sequences showed that MP possesses two unique changes in the RNA-binding domain and CP was found to be the conserved one with one change only. To the best of our knowledge, this is the first report of a CMV isolate infecting S. sclarea.