Development of cryopreservation protocol for banana cultivar 'Ambul' (Musa sp.) using vitrification technique

The germplasm of banana is diverse and the cultivar 'Ambul-Nadee' (Musa acuminate spp. AAB) is one of the most popular among Sri Lankans and can be grown in most agro-ecological zones. The cultivar is released by the Department of Agriculture, Sri Lanka, in 1992 for general cultivation. The presence of its characteristic flavor, aroma and small size inherits a great potential for increased production to serve the export market. Cryopreservation has been introduced as a new technique of conservation of germplasm and an important tool for long-term storage of plant genetic resources. This overcomes the problems related to subculturing which reduces the time and the labour requirements for managing in vitro genebanks and eliminates somaclonal variation. Therefore, this study focused on developing a cryopreservation protocol using in vitro derived shoot meristems by the vitrification technique, considering the thawing temperature, thawing time and regeneration medium. Thawing temperatures of 40 and 42°C were tested and 1- and 2-min thawing times were applied. For the regeneration medium MS medium supplemented with i) 17.7 µM 6-benzylamionpurine, and ii) 10.2 µM of 6-benzylamionpurine + 10.2 µM of indole-3-acetic acid were compared. After 4 weeks of culture period the number of regenerated, blackened and contaminated banana meristems were counted and recorded. Highest number of survival meristems (neither dead, nor regenerated) was observed in the sample thawed at 40°C. Overall, 70% of the meristems survived, 17% were blackened and the rest was contaminated, irrespective of the treatment. In control without immersing in liquid nitrogen, 20% of the meristems were regenerated.