This project advanced efforts to develop banana varieties with strong, durable resistance to Fusarium wilt Tropical Race 4 (TR4), a major threat to commercial banana production in Australia. With no effective chemical control and the fungus able to persist in soil for decades, genetic resistance remains the only viable long‑term solution for industry. The work helped identify new sources of resistance in wild seeded banana lines and clarified how these traits can be used in future breeding.

Researchers examined resistance in several wild banana types, building on earlier findings from the project Development of molecular markers for Fusarium wilt resistance in banana (BA17006) that located a resistance trait in the Malaccensis line on chromosome 3. In the current project, plants from a cross involving another resistant line, Calcutta 4, were screened against both Sub‑Tropical Race 4 (STR4) in Australia and TR4 in South Africa. DNA from resistant and susceptible plants was compared to identify genomic regions linked to resistance.

The work addressed the longstanding challenge of incorporating resistance from wild, seeded bananas into commercially acceptable varieties while retaining parthenocarpy and key agronomic traits. The project confirmed that Calcutta 4 carries a distinct resistance source located on chromosome 5, separate from the Malaccensis trait. This discovery means both resistance types can potentially be combined to deliver stronger and more durable protection against TR4.

The project will enable the development of a new molecular marker for the Calcutta 4 resistance trait, to be used alongside the existing Malaccensis marker. These tools will speed early‑stage selection in breeding programs, improve access to suitable resistant germplasm, and strengthen collaboration with international breeding efforts—ultimately supporting the development of TR4‑resistant varieties for Australian growers.