Broadening the genetic base of the diploids with biotic resistance to accelerate banana (Musa acuminata L.) breeding

Abstract

Success of banana (Musa acuminata L.) breeding mainly depends on the male diploid parents used in the hybridization program. Developing intermediate diploid breeding lines with fertile pollen production ability, resistance to biotic and abiotic stresses, and fruit quality through the diploid x diploid strategy is the key step in improving commercial cultivars. Till now, at the global level only a limited number of diploid accessions is being used in banana breeding programs. In the present study, through the diploid x diploid breeding strategy, the genetic diversity of diploids has been broadened by developing nine polleniferous biotic-stress-resistant diploid lines. Among these, except for two progenies (P), all were resistant to the eumusae leaf spot disease. A single progeny (P 134) showed resistance to root-lesion and root-knot nematodes, whereas P 148 showed moderate resistance to root-knot nematodes alone. Three progenies of cv. Rose x Pisang Lilin (P 427, P 428 and P 429) were moderately resistant to banana stem weevil. Irrespective of cross combinations, barring two, all other progenies exhibited resistant reactions to fusarium wilt, Foc race 1 under both hot spot and pot culture screening. Among the nine diploid progenies, P 427, P 428 and P 429 were the best prospects to contribute multiple resistance against pests (banana stem weevil) and diseases (eumusae leaf spot and Foc race 1), whereas P 134 could be used as the resistant source for root-knot nematodes. The pyramiding of resistant/defense-related alleles in the progenies has been confirmed through SSR markers associated with Foc resistance. These polleniferous resistant improved diploid progenies are the potential source for accelerating the banana breeding program for improving biotic resistances in the triploid commercial cultivars through reconstructive breeding and/or for stacking the resistant genes in other genetic backgrounds.