Genome mapping and genetic analysis of the black leaf streak resistance in bananas

Banana production is severely threatened by the Black Leaf Streak Disease (BLS) caused by Mycosphaerella fijiensis. Numerous chemical applications are needed to control the fungus' impact on leaves which reduces yields and causes premature ripening of fruits. Genetic improvement for resistance to BLS appears as the most durable, cost and environmentally efficient control. Screening for resistance has led to the identification of two forms of resistance reported as High Resistance (HR, hypersensitive response) and Partial Resistance (PR). In connection with the breeding program, a genome mapping approach for genetic and QTL analyses was developed to characterise the HR form. An F2 segregating population of 175 plants was obtained from a cross between two wild seeded banana accessions, Musa acuminata burmannicoides type Calcutta 4 and M. a. banksii type Madang. A linkage map was constructed with AFLP markers in association with RFLP and SSR markers to anchor the linkage groups to the core banana genetic map. Resistance is being evaluated by field observations in two locations at CRBP in Cameroon and also by controlled inoculations. The results will serve to characterise the genetic determinism of BLSD resistance with the objective to develop marker assisted selection. (Texte intégral