ESTABLISHMENT OF VIRUS-FREE BANANA (MUSA SPP.) MOTHER STOCK FOR PRODUCTION OF CERTIFIED BANANA PLANTS AND BANANA STREAK VIRUS TESTED TISSUE CULTURE SEEDLINGS

Banana (Musa spp.) is one of the most widely consumed fruits and an attractive perennial fruit crop for small farmers in Kenya. However, viral diseases such as Banana streak virus (BSV) have contributed to the poor performance of banana seedling production. Knowledge of the prevailing BSV isolates in the country and establishment of virus indexed banana plants is therefore important, since virus-free indexed mother stocks are required for micropropagation. The present study was aimed at screening for BSV in five commercial banana cultivars and establishment of a vigorous, virus-free mother stock for future supply of certified banana suckers. Cultivars used included ‘FHIA-17’ (AAAA genome), ‘FHIA-18’ (AAAB genome), ‘Chinese Cavendish’ (AAA genome) and ‘Solio’ and ‘Nusu Ng’ombe’ (AAA-EAHB genome). Immuno capture polymerase chain reaction (IC-PCR) technique was used to identify presence and type of isolates in each of the tissue culture seedlings before field establishment and one month and six months after their establishment in the field orchard. Results showed variation in severity of infection among cultivars in the greenhouse before field establishment with 58% infection for ‘FHIA-17’, 48% for ‘FHIA-18’, 41% for ‘Chinese Cavendish’, and 6% for ‘Solio’ and ‘Nusu Ng’ombe’. One month after establishment of virus-free material, there was 10% infection detected in the first three cultivars. These results confirmed that tissue culture alone is not efficient in elimination of BSV and there is need to index all plants routinely after field establishment. Molecular indexing confirmed infection in 55% out of the 200 samples tested using three primers BSV-GF, BSV-Cav and the degenerate primer Badna 1A-4’.