Generation and Retention of Defective RNA3 from Cucumber Mosaic Virus and Relevance of the 2b Protein to Generation of the Subviral RNA

A defective RNA3 (D3Y alpha) of strain Y of cucumber mosaic virus (CMV-Y) was examined on host-specific maintenance, experimental conditions, and a viral factor required for its generation in plants. D3Y alpha was stably maintained in cucumber but not in tomato plants for 28 days post inoculation (dpi). D3Y alpha was generated in Nicotiana tabacum or N. benthamiana after prolonged infection in the second and the third passages, but not in plants of N. benthamiana grown at low temperature at 28 dpi or infected with CMV-Y mutant that had the 2b gene deleted. Collectively, we suggest that generation and retention of D3Y alpha depends on potential host plants and experimental conditions, and that the 2b protein has a role for facilitation of generation of D3Y alpha.