Banana Fusarium wilt: an on-going battle

Presented by Dr Elizabeth Aitken Associate Professor, School of Agriculture and Food Science Affiliate Associate Professor, Queensland Alliance for Agriculture and Food Innovation ABSTRACT In the mid-20th century worldwide commercial banana production was seriously curtailed by Fusarium wilt. The causal agent was what is now known as race 1 of the fungus Fusarium oxysporum f.sp. cubense (Foc) and as a consequence, the then resistant Cavendish took over as the dominant commercial cultivar. Now Cavendish is threatened by a strain known as Foc tropical race 4 (TR4). How the different races of Foc differ is not known but pathogenicity genes are hypothesised to be involved. In the tomato-infecting strain Fusarium oxysporum f.sp. lycopersici (Fol ), a novel suit of pathogenicity genes known as secreted in xylem (SIX) genes have been reported. Using sequence analysis on an extensive collection of isolates of Foc, we have revealed a correlation between unique combinations of SIX genes and the races of Foc. It is hoped that this will lead to identification of key factors involved in pathogenicity of Foc on banana as well as the development of a race specific molecular diagnostic for Foc. Meanwhile in our studies on the wild diploid banana, Musa accuminata subsp. malaccensis, we have identified what appears to be a single dominant resistance gene to Fusarium wilt, including resistance to TR4.

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