CURRENT STATUS AND GENETIC VARIABILITY OF CUCUMBER MOSAIC CUCUMOVIRUS (CMV) ISOLATES INFECTING MAJOR CUCURBITS AND SOLANACEOUS VEGETABLES IN POTHWAR REGION OF PAKISTAN.

Cucumber mosaic cucumovirus (CMV) is a known devastating pathogen and menace threat to several important vegetables worldwide including Pakistan. This study was conducted to determine the incidence, distribution and genetic variability of CMV isolates infecting cucurbits and solanaceous vegetables in the Pothwar region of Pakistan, a rich region for vegetable production. Symptomatic leaf and fruit samples were subjected to double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA) using polyclonal antibodies for CMV. Moreover, it was further characterized by Triple Antibody Sandwich ELISA (TAS-ELISA), molecular assays and genetic recombination. The pathogen was prevalent in all districts and detected in all 10 tested vegetables i.e. cucumber, round gourd, watermelon, melon, pumpkin, bitter gourd, ridge gourd, smooth gourd, chilli and tomato, with an average incidence ranging from 11.85% to 25.89%, with the highest incidence in district Attock (25.17%) followed by Rawalpindi (23.04%), Jhelum (18.57%), Chakwal (18.30%) and Islamabad (14.45%). Cucumber, tomato, watermelon and chilli were found to be most affected by CMV with an average disease incidence (D.I.) of 45.38%, 21.15%, 19.39% and 19.05%, respectively. Capsid protein (CP) cistron nucleotides based In silico restriction and Phylogenetic analyses revealed that among 10 Pakistani CMV under studied isolates; the four viz., AAJAC, AARpCu, AAHAWM and AACCu isolates were grouped as member of CMV subgroup IB and they shared 94.96% identity with each other while rest of the six isolates viz., AARCF, AARwCu, AARTF, AAHAPu, AAICu and AAJABG grouped in to CMV subgroup II with 92.8% identity among themselves. In recombination detection analysis, the Pakistani CMV isolate AAICu (MH119070) was found likely to be a recombinant between the Indian (X89652) and Pakistani (MH119068) isolates with recombinant breakpoints between 370^th and 630^th nucleotides. Further research is needed to comprehend the economic impact of the virus and breeding programs for screening of resistant genotypes as per recombinant strains and there is also a need to focus on training of farmer communities to manage disease through adaption of resistant cultivars and controlling vector populations. [ABSTRACT FROM AUTHOR]