Effect on Increasing Temperature on the Pathogenic Fitness of Fusarium Pseudograminearum

Abstract

With rising temperatures projected for a changing climate, it is of particular importance to determine how plant pathogens and plant disease profiles will be influenced in the future. In this study, we investigated the effect of increasing temperature on the pathogenic fitness of Fusarium pseudograminearum, an important necrotrophic pathogen associated with wheat and barley crown rot (CR) in Australia. Currently, CR costs an average of AU$79 million in losses each year through the reduction of crop yields. Under optimum environmental conditions, F. pseudograminearum also has the ability to produce harmful mycotoxins such as Deoxynivalenol (DON) in infected tissue, including in grains. In a glasshouse environment, we examined the influence of four diurnal temperature treatments 15/15 oC, 20/15 oC, 25/15 oC and 28/15 oC on pathogen colonisation, DON production and stem base browning of eleven wheat lines (Triticum spp.) artificially inoculated with F. pseudograminearum. Overall, results from two independent repeats indicate that stem base browning, as well as, pathogen colonisation and DON production in both the stem base and flag leaf node of mature plants were highest at 15/15 oC and generally all measures were reduced with increasing temperature. Wheat line also influenced the level of stem base browning, pathogen colonisation and DON production, but the influence declined with increasing temperature. There was a strong correlation between DON in stem base tissue and stem base browning, but stem base browning was not a good predictor of pathogen colonisation in the stem base. We report that a combination of host resistance and rising temperature will reduce pathogen fitness and crown rot under increasing temperature, but further studies combining the effect of rising CO2 are essential for more realistic assessments.