A Pipeline for Generating Mutant Bananas Resistant to Fusarium Wilt TR4

Triploid bananas are sterile, parthenocarpic, and an obligate vegetatively propagated crop. Lack of meiosis hampers traditional breeding. Exported Cavendish bananas are clones and susceptible to diseases including Fusarium wilt caused by tropical race four (TR4). In recent years TR4 has been identified in nine countries suggesting that it is spreading geographically and threatening global banana production. Work with banana TILLING showed that mutations can be induced in the genome at a high density and chimeric sectors rapidly dissolved. This suggests that a mutation breeding approach is suitable to develop disease resistant bananas. For success, a large mutant population must be generated and efficiently screened to recover rare improved plants. Each step of the breeding pipeline (clonal production, mutagenesis and disease screening) represents a bottleneck that is difficult to overcome in a single laboratory. We are developing a large mutant population of approximately 10,000 lines by treatment of shoot tips with gamma irradiation, and modifying sequencing techniques to recover large genomic indels caused by the treatment. In parallel to this, the IAEA is developing a multi-laboratory Coordinated Research Project with a focus on banana disease resistance.