In vitro selection for Fusarium wilt resistance in banana I. Co-cultivation technique to produce culture filtrate of race 1 Fusarium oxysporum f. sp. cubense.

摘要

In vitro mutation breeding combined with toxin-determined selection is a promising strategy to obtain disease resistant plants in species where sexual propagation is limited. A co-cultivation technique to produce effective crude filtrates, i.e., mixed toxin, of fungus culture was developed for in vitro selection of banana mutants. Fusarium oxysporum f. sp. cubense race 1 was co-cultivated with banana tissue cultures which were whitish compact clusters of proliferating shoot meristems, referred as multiple-bud-clump. Crude filtrates of the cultivated medium were obtained by passing through a 0.45μm pore size membrane. Multiple-bud-clumps of resistant and susceptible banana varieties were cultivated on the medium supplemented with the filtrates toevaluate toxin activity. Crude filtrates produced by co-cultivation showed higher specificity of toxic activities on banana than that produced by sole cultivation. The banana variety used was important for the co-cultivation technique. The co-cultivationof the fungus with a multiple-bud-clump of cv. Maca, which is susceptible to the Fusarium disease, produced highly toxic filtrates to the susceptible variety (Maca) and less toxic to resistant variety (Nanicao). The results showed the crude filtrates should be useful for in vitro selection of disease resistant plants.