Diversity of Apple mosaic virus Isolates in India Based on Coat Protein and Movement Protein Genes.

Apple mosaic virus (ApMV), an Ilarvirus is one of the most common pathogens of apple worldwide. During field surveys in commercial plantations of Himachal Pradesh and Jammu & Kashmir, observations of bright chlorotic mosaic like symptoms on apple trees indicated probable infection by the virus, which was later detected by double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA). An incidence of 24 and 28% (based on ELISA) was obtained as 6/25 and 15/53 samples from HP and J&K were positive, respectively. An amplification of approximately 700 and 850 bp was obtained for coat and movement protein genes (CP and MP), respectively. The CP was 223 amino acids in length and showed 87-99% identity when compared to 21 ApMV isolates. Whereas, MP (286 amino acids) showed 91-95% identity with other isolates. However, the gene sequences were quite conserved among Indian isolates and grouped together phylogenetically. CP of the Indian isolates showed maximum identity of 95% with Korean isolate (AY 125977) in apple and in other host these showed a maximum identity of 98% to Czech Republic pear isolate. MP showed maximum identity with Chinese isolate i.e., 95%. The diversity study will also help in analyzing variability among the isolates and also to formulate diagnostic and resistance strategies.