Tipping the Balance: Cell Death Control for Fungal Disease Resistance /Stress Tolerance in Banana

The vast majority of bananas grown today have undergone limited agronomic improvement through conventional breeding. A major reason for this is that most cultivars are essentially sterile. An alternate strategy to improve current cultivars is through transgenic modification.  Currently, there are no effective control methods for the most important fungal diseases of banana; Black Sigatoka (Mycosphaerella fijiensis) and Panama Wilt (Fusarium oxysporum), both of which have necrotrophic life styles where nutrient acquisition occurs from dead tissue. Using a novel, improved monocot transformation procedure we have and are continuing to develop banana lines harboring genes that negatively control programmed cell death. Our previous data from several pathosystems, has demonstrated that control of cell death is key to the outcome (Resistance vs. Susceptibility) of a given necrotroph-plant interaction. As a result of  blocking the ability of these fungi to kill host tissue, disease is impeded. Moreover as we have shown with other crops, abiotic (drought) stress tolerance in banana was also observed when these transgenes are expressed, suggesting the existence of shared pathways. To identify additional plant genes with the potential to provide enhanced agronomic traits, we have designed functional genomics screens in yeast and coupled with the use of bioinformatics, we are identiftying new plant derived  candidate genes, and generating novel germplasm. Field studies are underway with several of our transgenic lines.