SCREENING OF CASSAVA GENOTYPES FOR RESISTANCE TO BACTERIAL BLIGHT USING STRAIN x GENOTYPE INTERACTIONS

Abstract

Twenty-four improved and local genotypes of cassava (Manihot esculenta) from Togo were screened under controlled conditions for resistance to cassava bacterial blight by stem-inoculation with four highly virulent Xanthomonas axonopodis pv. manihotis strains from different African origins. The local genotypes Nakoko and Toma159 were most susceptible to the four strains, while most other genotypes, including the reference genotype Ben86052, with susceptible reaction to at least two strains, were resistant to at least one strain. Six genotypes showed a resistant reaction to the four strains, the local genotype Gbazekoute and the improved CVTM4 from the International Institute of Tropical Agriculture (IITA) being the most resistant. Six groups of genotypes with differential reactions to the strains were identified, which allowed the strains to be defined as pathotypes.