Somatic embryogenesis from immature male inflorescences of East African highland banana CV ‘ Nakyetengu'

Abstract

The East African highland bananas (Musa spp. cv. EA-AAA), the most important staple food in Uganda, are susceptible to a range of pests and diseases. This has been attributed to a low genetic base of this banana group and thus the need to create a wide genetic base through development of resistant cultivars. The use of genetic transformation (engineering) approach has been identified as a potential option that could be utilised to facilitate and/or enhance the process of developing resistance cultivars. The objective is to establish an In vitro regeneration system for East African (EA-AAA) highland bananas. Cell suspensions are the material of choice for genetic transformation because of their regeneration capacity through somatic embryogenesis. In this study, immature male flowers of cultivar ‘Nakyetengu' were isolated and initiated on callus induction media designated M1, M2, M4, M6, M7 on petri-dishes. Cultures were placed under controlled light and temperature conditions and monitored for embryogenic callus formation. Embryogenic callus composed of somatic embryos was obtained on medium M1 only, after a culture period of 3.5 to 4 months. Direct somatic embryo germination was achieved on embryo germination medium. Somatic embryo germination was recorded at a rate of 66.7%. Plant recovery was achieved on standard MS hormone free medium, all being normal plants with root and shoot at weaning. With regard to the pest and disease problems of the East African highland banana, these findings underscore the fact that somatic embryogenesis is essential in the development of an In vitro regeneration system and is a critical step for development of resistant varieties through genetic transformation.