Response of <i>Fusarium pseudograminearum</i> to Environmental Stress and Fitness Differences Between 3AcDON and 15AcDON Populations

Fusarium crown rot (FCR), caused by <i>Fusarium pseudograminearum</i>, poses a significant threat to global wheat production. To elucidate the mechanisms driving FCR prevalence under drought and saline conditions and the distinct geographic distributions of 3-acetyl-deoxynivalenol (3AcDON) and 15-acetyl-deoxynivalenol (15AcDON) populations, this study investigated the biological characteristics of 40 <i>F. pseudograminearum</i> strains. These characteristics included conidiation capacity, pathogenicity, and responses to temperature, drought, and salt stress under simulated laboratory conditions. The results indicated no significant differences in conidial production or seedling pathogenicity between the two populations. Optimal mycelial growth occurred at 20 to 25°C, with the 15AcDON population exhibiting larger growth than the 3AcDON population, except at 15°C. Moderate drought stress significantly enhanced mycelial growth, particularly in the 15AcDON population, which showed significantly larger colony diameters than the 3AcDON population at 20 to 35% PEG6000 concentrations. Both populations showed strong tolerance to osmotic stress (1 M sorbitol) and moderate salt stress (1 M NaCl), though no genotype-specific differences were observed under these conditions. These findings highlight the role of temperature and drought in shaping the geographic distribution of <i>F. pseudograminearum</i> populations and provide insights into the environmental adaptability of the fungus, offering a scientific basis for predicting FCR epidemics under global climate change.