Characterization of the cell wall integrity MAPK pathway in Fusarium graminearum

In the fungal phytopathogen Fusarium graminearum, the core of the mitogen-activated protein kinase (MAPK) cascade known as the cell wall integrity (CWI) pathway is formed by Bck1 (MAPKKK), Mkk1/2 (MAPKK) and Mgv1 (MAPK). Rlm1 is the only target that has been suggested for Mgv1. The objective of this thesis was to generate and characterize F. graminearum transformants that produce a high abundance of a phosphorylated Mgv1 protein that could be used in future assays for screening its candidate targets. MGV1 in locus constitutive overexpression increased the amounts of the Mgv1 phosphorylated protein, and did not cause phenotypical changes. MKK1197E,203E in locus constitutive overexpression inhibited the expected continuous Mgv1 phosphorylation, and negatively affected mycelial growth and virulence. In addition, MKK1197E,203E_OX strains showed increased resistance to osmotic stress, and higher abundance and phosphorylation of another MAPK (Hog1), opening questions regarding the cross-talk between the CWI and the HOG MAPK pathways