Evaluation of in Vitro Protocols for Elimination of Banana Streak Virus from Tissue Cultured Explants in Banana Seedling Production

The banana industry in Kenya is threatened by the presence of Banana streak virus (BSV). The Jomo Kenyatta University of Agriculture and Technology (JKUAT) commercial banana laboratory uses tissue culture (TC) technique for mass propagation of plantlets which are free from most disease causing organisms for commercial purposes. To evaluate in vitro protocols for production of Banana Streak Virus-free TC banana planting materials for farmers, leaf samples were collected from Thika, Kisii, and JKUAT orchards for indexing. The corms were taken through the TC procedure up to the 2nd subculture stage after which they were subjected to three virus elimination techniques; chemotherapy, meristem tip culture and thermotherapy for evaluation. Indexing for BSV using PCR BSV indicated 90, 80 and 40% infection levels for Kisii, JKUAT and Thika orchards, respectively. For chemotherapy evaluation, concentrations of between 10 and 40 mg/l were used resulting in 0 to 90% virus elimination. For thermotherapy, 27°C (control), 32°C, 34°C, 36°C and 38°C for 10 days, resulted in 0 and 90% virus elimination. Meristem tip culture at 1, 2, 3, 4 and 5mm (control) gave between 0 and 90% virus elimination, respectively. The study indicates that BSV can be eliminated using chemotherapy, thermotherapy and meristem tip culture. Chemotherapy using salicylic acid at 20mg/l can be used to eliminate BSV up 90%. It is also easy to implement since it is incorporated into the medium.