RACE-1 FUSARIUM-WILT TOLERANCE ON BANANA PLANTS SELECTED BY FUSARIC ACID

The selection of tolerant variants to race 1 fusarium wilt of banana w as carried out through the effects of fusaric acid on in vitro banana multiple bud clumps (MBCs). The MBCs of Maca cultivar (Musa sp., AAB, Silk), which is susceptible to the race 1 fusarium wilt, were used. An d, Nanicao cultivar (AAA, Cavendish subgroup) was used in the tolerant tests as control of a disease tolerant variety. Firstly, to aim at de termining an appropriate concentration of the toxin for the tolerant s election, the MBCs were cultured on the Modified Murashige & Skoog med ium supplemented with 0.05 to 1.6 mM fusaric acid. The growth on both cultivars was completely inhibited on the medium containing 0.1 mM fus aric acid. Tolerant variants of 'Maca' were, then, selected with 0.1 m M fusaric acid after chemical mutagen treatment. The results showed an increased tolerance of the selected 'Maca' plants to the race 1 fungu s in greenhouse tests. In vitro selection by fusaric acid is a very us eful method for obtaining fusarium disease tolerance, although the tol erance mechanism of the selected plants may be different from that of existing tolerant cultivars.