Elimination of coexisting canna yellow mottle virus, bean yellow mosaic virus and cucumber mosaic virus from Canna generalis cv. black knight through in vitro chemotherapy of rhizome explants

During our previous study, the mixed infection of canna yellow mottle virus (CaYMV), bean yellow mosaic virus (BYMV), and cucumber mosaic virus (CMV) was identified in a Black Knight cultivar of canna exhibiting severe yellow streak and mottling symptoms. Before the development of the virus-free plants, the ability of callogenesis and organogenesis from the ovary, stalk, and rhizome explants was tested on different concentrations and combinations of TDZ, NAA, BAP, and Ads growth regulators. The performance of rhizome explants was above all the explant types and 33.33 +/- 1.67 rhizomes (out of 50 placed) showed callus development on ME medium (MS supplemented with 0.8 mg/L TDZ and 0.25 mg/L NAA) and further on a refined M4 medium (MS supplemented with 4.0 mg/L BAP, 1.0 mg/L NAA and 50 mg/L Ads) produced 4.06 +/- 0.16 shoots per explant. The development of virus-free plants was attempted by in vitro chemotherapy using ribavirin. Not only in callogenesis and shoot development but also in the ribavirin treatments, rhizomes developed about 3.78 +/- 0.68 shoots per explant on 40 mg/L ribavirin in the ME medium. These optimizations suggested that ME medium for callogenesis, M4 medium for shoot development and the treatment of 40 mg/L ribavirin for 30 days at M4 medium was effective. The elimination of coinfection of all three viruses from rhizome explants of 0.5 cm(2) of the Black Knight cultivar was attempted. Consequently, a total of 53.33% of plants free from all three viruses (48 out of the 90 plants developed) were obtained when screened by RT-PCR and PCR for their absence.

Automated summary

The mixed infection of canna yellow mottle virus (CaYMV), bean yellow mosaic virus (BYMV), and cucumber mosaic virus (CMV) in canna plants was studied. The development of virus-free plants was attempted through callogenesis and organogenesis using different growth regulators. The optimization of mediums and treatments resulted in successful elimination of the viral infections and the production of virus-free plants.