| Fusarium head blight (FHB) infected by Fusarium graminearum is a worldwide fungus disease. It costs not only the reduction of yield and quality but also producing mycotoxins in kernel, which is a huge threaten to food security and the health of human and animals. To find out an effective way to combat FHB, it is essential to study the pathogenic mechanism of Fusarium graminearum on wheat. Rho family is one of the important members of the Ras superfamily. As one kinds of GTP-binding proteins, Rho family proteins participate in multiple signal transduction pathways and play the role as a "molecular switch". Bioinformatics methods were used to acquired FgRho4 (Rho4 homologous protein in Saccharomyces cerevisiae) from F. graminearum database. It was found that the phenotypes of the gene knock-out mutants are quite different from wide-type strain PH-1. It showed that the growth rate of mycelia slowed down seriously, along with decreased in aerial hyphae and sporulation. The septa were disappeared in hypha and conidia of FgRH04 deletion mutants. Moreover, the mutants produced abnormal conidia, lost the ability of sexual reproduction and pathogenicity. All these defective phenotypes were restored in complementary strains of this gene. Two putative GEFs (guanine nucleotide exchange factors) of FgRho4 are acquired by homologous comparison. As one of the GEFs genes, FgBUD3 was knocked out and the deletion mutant gave the similar defective phenotypes with FgRHO4 deletion mutants. Above all, Rho4 is required in mycelial growth, septum formation, sexual reproduction, and pathogenicty process in Fusarium graminearum. |
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