Figure 3

Effects of MAPK Activators on Radial Expansion, Sporulation, and Intracellular Glycerol in C. militaris. (a) Representative images of C. militaris Ywt and Ydga cultured in PDA with or without various MAPK activators. Congo red, a cell wall integrity (CWI) activator, considerably inhibited both radial expansion (b) and sporulation (c) in both strains of C. militaris. (d) H₂O₂, an oxidative stress inducer, and NAC, an antioxidant agent, substantially suppressed radial expansion in both strains. (e) H₂O₂ considerably increased spore density in Ywt strain but not in Ydga strain, while NAC had no substantial effect on sporulation in either strain. KCl and NaCl, two osmotic stressors, considerably inhibited radial expansion (f) but promoted sporulation (g) in both strains. Osmotic stressors substantially increased intracellular glycerol concentrations in Ywt (h) and Ydga (i). Glycerol concentrations exhibited a positive correlation with spore density but a negative correlation with circle areas in Ywt (J) and Ydga (K). CR = PDA + 200 μg/ml Congo Red. H₂O₂ = PDA + 0.04% H₂O₂; NAC = PDA + 200 mM N-AcetylCysteine. NaCl = PDA + 0.4 M NaCl; KCl = PDA + 0.4 M KCl; Sor = PDA + 1 M Sorbitol. The data are presented as ranges, means, and standard deviations, with a sample size of n = 5. *, **, *** represents a significant difference (actual p values are presented in supplementary Table S9–S11). SD refers to standard deviation. Culture Conditions indicates the strain name and the corresponding media. Significance was determined using a one-tailed t-test for two independent means, with an alpha level of 0.05.