Molecular Virology, National Botanical Research Institute, Lucknow-226001 Uttar Pradesh.
Chrysanthemum morifolium of family Asteraceae, commonly known as ‘garden chrysanthemum’ is grown in pots and gardens for beautiful bloom of various size, shape and colour. Chrysanthemum has been recognized among the five important commercially potential flower crops. In terms of production, it accounts for about 18.6% of the total cut flower production. Chrysanthemum aspermy virus (CAV), Cucumber mosaic virus (CMV), Chrysanthemum virus B (CVB), Tomato spotted wilt virus (TSWV), Chrysanthemum stunt viroid (CSVd) and Chrysanthemum chlorotic mottle viroid (CChMVd) are the most important pathogens have been found to infect chrysanthemums at a very high frequency in nature. Chrysanthemum plants showing characteristics ring spots on leaves have been observed in the gardens in and around Lucknow. The pathogen could be transmitted by sap inoculations from naturally infected chrysanthemum to various cultivars of tobacco, which showed local ring spots and severe systemic mosaic symptoms. Association of CMV and CAV was detected by Western blot immuno-assay using antibodies of both the viruses. Presence of CMV and CAV infection was further confirmed by RT-PCR in samples of total RNA isolated from infected leaves of chrysanthemum as well as tobacco plants. The primers from conserved region of coat protein gene of CMV and CAV were used for this purpose. The amplicons of expected size ~654 and ~660 bp were obtained from primers specific for CMV and CAV respectively, when PCR products were electrophoresed on 1% agarose gel. Both the amplicons were cloned, sequenced and data was submitted to Genbank under accession no: DQ028777 (CMV) and DQ191798 (CAV). The NCBI blast analysis showed 99% homology of CMV isolate with CMV strains, whereas 98% homology of CAV isolate was found with other CAV strains. Therefore, unusual ring spot symptoms on chrysanthemum was suspected due to the synergistic infection of CMV and CAV, however, univocally it needs further histo-pathological investigations.
