RANDOM AMPLIFIED POLYMORPHIC DNA (RAPD) DETECTION OF DWARF OFF-TYPES IN MICROPROPAGATED CAVENDISH (MUSA SPP AAA) BANANAS

A RAPD marker specific to the dwarf off-type (hereafter known as dwarf ) from micropropagation of Cavendish banana (Musca spp. AAA) cultivars New Guinea Cavendish and Williams was identified following an analysi s of 57 normal (true-to-type) and 59 dwarf plants generated from sever al different micropropagation events. Sixty-six random decamer primers were used in the initial screen, of which 19 (28.8%) revealed polymor phisms between normal and dwarf plants. Primer OPJ-04 (5'-CCGAACACGG-3 ') was found to amplify an approx. 1.5 kb band which was consistently present in all normal but absent in all dwarf plants of both cultivars . Reliable detection of dwarf plants was achieved using this marker, p roviding the only available means of in vitro detection of dwarfs. The use of this marker could facilitate early detection and elimination o f dwarfs from batches of micropropagated bananas, and may be a useful tool in determining what factors in the tissue culture process lead to this off-type production. Other micropropagation-induced RAPD polymor phisms were observed but were not associated with the dwarf trait.