Spermine Modulation of Fusarium culmorum Infection in Winter Wheat (Triticum aestivum L.): Biochemical and Transcriptional Responses of Selected Antioxidant-Related Genes

Our study investigated the protective effects of seed priming with 5mM polyamine spermine (Spm) on the biochemical and transcriptional responses of winter wheat during Fusarium culmorum infection. We tested the effects of the priming in two age groups of plants via two pathogen infection approaches. In the seed-inoculated plants, infection with F. culmorum induced severe cellular damage and oxidative stress, as evidenced by increase in electrolyte leakage, thiobarbituric acid reactive substances, and hydrogen peroxide levels. The pathogen also triggered metabolic changes in the plants by elevating reducing sugars, free proline, total osmotically active solutes and peroxidase activity, while at the same time suppressing the activity of catalase. On the other hand, the 5 mM Spm seed priming significantly mitigated this pathogen-induced damage. The priming effectively lowered most oxidative stress biomarkers and reduced the over-accumulation of osmolytes. Spm also restored the suppressed catalase activity, stabilized superoxide dismutase activity and altered the pathogen-mediated transcriptional response of the tested defence enzymes. Furthermore, spermine priming enhanced glutathione S-transferase activity in infected 30-day-old plants. Overall, our findings demonstrate that 5 mM spermine seed priming modulates the physiological response to F. culmorum in wheat by optimizing antioxidant enzyme activity and returning the studied metabolic parameters to near control levels.