Department of Biotechnology, Dr Y.S. Parmar university of Horticulture & Forestry, Nauni- Solan-173 230, India.
Abstracts of the papers presented at the XVIII National Conference of Indian Virological Society at Post Graduate Institute of Medical Education and Research, Chandigarh, India, December 11–13, 2008.
Cucumber mosaic cucumovirus (CMV) belonging to genus cucumovirus of family bromoviridae has a wide range of hosts (as many as 191 host species in 40 families). Tomato aspermy virus (TAV) and Peanut stunt virus (PSV) are two other viruses that are presently admitted as the species in this genus. Cucumis sativus L. is one such commercially important vegetable crop that is highly susceptible to CMV infections. The genome of Cucumber mosaic virus is tripartite. Three to four linear, positive sense, single -stranded, RNA segments are distributed among 3 particle types of different size. RNA 4 is a sub-genomic messenger for coat protein (ORF 5-3b), derived from RNA 3. It is widely known that coat protein (CP) of a plant virus is not only a determinant of its antigenic properties but also responsible for the virus-vector relationship and their mode of transmission. Thus, comparative analysis of coat protein region was conducted to deduce evolutionary status of the virus. Serological diagnosis through DAS-ELISA confirmed presence of CMV in various fields of Dr. Y.S. Parmar UHF Nauni, Solan. Phylogenetic tree construction employing four techniques, namely, Neighbor-Joining (NJ), Unweighted Pair Group Method of Arithmetic Averages (UPGMA), Maximum Parsimony (MP), Maximum Likelihood (ML) and their analyses for all 12 countries along with the world trees was also pursued. CP test sequence of Cucumber mosaic virus from India shared impressive homology of 43%-97% at nucleotide level and 43%-96% at protein level with the rest 195 sequences scrutinized from around the world. Six motifs were identified in each protein sequence when scanned against PROSITE database. These were N-glycosylation site, cAMPand cGMP-dependent protein kinase phosphorylation site, Protein kinase C phosphorylation site, Casein kinase II phosphorylation site, N-myristoylation site and Amidation site. Present analysis elucidated high evolutionary rates of cucumoviruses attesting their cosmopolitan nature and rampant spread. These changes are replicating in the protein sequences, though at a slower rate, thereby, helping them to evade their host defence mechanism.
