Molecular characterization of Cucumber mosaic virus subgroup II isolate associated with cucumber in Bangladesh

摘要

Cucumber mosaic virus (CMV) associated with severe cucumber ( Cucumis sativus L.) mosaic disease was identified in leaf samples collected from 13 districts of Bangladesh during the period 2017–2020. Leaves and fruits with typical mosaic disease symptoms were observed under field conditions. Infected leaves were first screened by DAS-ELISA and the infection by CMV was further confirmed through RT-PCR employing primers specific to the conserved region and coat protein of CMV RNA3. The full length amplified RNA3 was cloned and sequenced. Sequence analysis showed that the RNA3 sequence of the isolate had the highest (98%) similarities with an Indian isolate (CMV-Palampur). Based on the highest sequence identities and close phylogenetic relationship, the causal virus of mosaic disease in cucumber was identified as an isolate of CMV belonging to subgroup II. All the conserved motifs of CMV RNA3 at both nucleotide and amino acid level were found as well. Recombination analysis showed that the probable parents of this isolate are CMV-Tsh and CMV-CTL strains from China. This virus strain might have got introduced in Bangladesh through imported seeds of Cucumber from other Asian countries. To the best of our knowledge, this is the first-ever report of incidence of CMV subgroup II from Bangladesh. The isolate is designated as CMV-BD.