Hygromycin-resistant transformants of Magnaporthe grisea, generated mainly by REMI (Restriction Enzyme-Mediated Integration), were screened for their ability to infect rice plants. Out of 125 transformants five showed changes in pathogenicity. The T108 and T93 mutants caused few lesions in rice leaves, while the T251 mutant was non-pathogenic. The alteration in pathogenicity of T108 was accompanied by reduced development in culture. The T41 mutant caused small and limited round lesions. The incubation period of the T72 mutant was longer than that of the wild type. Furthermore, late germination and appresorium formation was detected in the T72 mutant. All mutants grew in minimum medium, suggesting that there were no auxotrophic-associated mutations. The T93 and T251 mutants presented similar phenotypes in culture, characterized by a brown-pigmented colony.
Pyricularia grisea; Pyricularia oryzae; rice blast; insertional mutagenesis; restriction enzyme-mediated integration; REMI; pathogenicity genes
