What was it all about?

Fusarium wilt - particularly that caused by Tropical Race 4 (TR4) of the fusarium pathogen - threatens the viability of Australia’s commercial banana production, as it does worldwide.  Once present in a plantation, the fungus persists in the soil or in alternative hosts and cannot be eradicated, and there are no known chemical controls. This leaves genetic resistance as the only viable option for Fusarium control.

To help identify disease-resistant banana varieties, this investment ran from 2019 to 2021 to develop molecular markers associated with different sources of genetic resistance to Fusarium wilt in banana.

Using molecular markers allows the prioritisation of varieties that are likely to be resistant through quarantine screening processes, avoiding the potential time and financial waste of importing and processing varieties that later prove to be susceptible.

The project generated new knowledge on the genetics of TR4 and Subtropical Race 4 (SR4) resistance. It was identified that both Calcutta 4 and SH3362 (a line from the Honduran (FHIA) breeding program) are heterozygous for Foc SR4 resistance.

The research team also strengthened Australia’s international collaboration and knowledge transfer activities to increase understanding of the genetics of resistance in wild diploid lines, and enhance genetic understanding and continuity of Fusarium wilt resistance research in international banana-breeding programs.

Additionally, in studies with the original Malaccensis resistance line, a more defined region on banana chromosome 3 was identified as the resistance trait location. This work is ongoing through international collaborations, to identify the gene/s conferring resistance and develop an associated gene-specific molecular marker.