Functional Analysis Of A Putative Homeobox Gene In Magnaporthe Grisea

In Magnaporthe grisea, homeobox genes may play a key role in cell type regulation of pathogenicity cycle. According to the conserved homeodomain sequences, we can easily find homeobox genes in M. grisea. Based on the M. grisea genome, 7 putative homeobox genes were obtained. We have generated two knock-out mutants,â–³MG0184-1 andâ–³MG0184-10, by deleting one of the putative homeobox genes, MGG₀0184．5．We tested whether their growth, mating, conidiogenesis and pathogenicity were changed in these mutants. Meanwhile, functional complement vector was constructed and transformed into the protoplasts of the knock-out mutants to observe whether the mutant phenotypes could be recovered.Our results were as follows:(1) The hypha of the two mutants grew a little faster than that of the wild-type Guy11 on CM plates. There was no difference in colony color between the wild-type and the knock-out mutants.(2) The deletion mutants, which were cultured for 10d under light, failed to produce any conidia. However, their conidiophores increased obviously.(3) Guy11 and the two mutants could all cause lesions in wounded leaves of barley and rice inoculated with mycelium plugs.(4) When mated with strain 70-15 of the opposite mating type, bothâ–³MG0184-1 andâ–³MG0184-10 can produce perithecia, as well as the wild-type Guy11．Based on the results above, we concluded that the homeobox gene, MGG₀0184．5, was involved in regulating cell differentiation during the development of M. grisea, which may be associated with conidiogenesis and hyphal growth, but not with the regulation of the infectious growth and sexual reproduction in the fungus. Further functional dissection of this gene will provide better knowledge of the pathway that the homeobox genes are involved in M. grisea.