Overexpression of the sck1 or sck2 gene can suppress the loss of PKA activity. F. graminearum has only one Sch9 ortholog but two genes encoding catalytic subunits of PKA. Whereas deletion of CPK2 had no detectable phenotype, the cpk1 mutant was reduced in growth, virulence, DON production, and conidiogenesis. The cpk1 cpk2 double mutant had more severe defects in growth and was non-pathogenic. In addition, Sch9 and PKA control parallel pathways that converge on the Rim15 kinase in S. cerevisiae. In M. oryzae, the rim15 deletion mutant has a slower growth rate, slightly increased sensitivity to Tropifexor hyperosmotic stress, and reduced hyphal melanization and virulence. In F. graminearum, the Fgrim15 mutant was reduced in conidiation and virulence. In S. cerevisiae, SCH9 also is involved in the signal transduction facilitator function of the Hsp90 chaperone complex that is required for the maturation of hundreds of diverse client proteins. The sch9 mutant has increased stress resistance. In human pathogen Cryptococcus neoformans, the sch9 deletion mutant also had increased thermal tolerance. In F. graminearum, the DFgsch9 mutant had increased tolerance to elevated temperatures during germ tube growth. Germ tubes of the DFgsch9 mutant were normal but the wild type produced apical and intercalary swollen bodies when incubated at 30uC. In F. graminearum, the DFgsch9 mutant had increased sensitivity to 0.7 M NaCl, suggesting that FgSCH9 is important for Tioconazole response to hyperosmotic stress. In the budding yeast, Sch9 is involved in response to hyperosmotic stress via its association with Hog1 and co-regulation of subsets of genes such as GRE2 and CTT1. Nevertheless, the DFgsch9 mutant had increased sensitivity to SDS and Congo red as well. In addition, we found that the DFgsch9 mutant had the hyphae-in-hyphae phenotype and increased tolerance to elevated temperatures. Therefore, it is likely that FgSCH9 is required for general stress responses in F. graminearum. Unlike the cpk1 cpk2 double mutant, the DFgsch9 mutant was still pathogenic.