Increasing durum wheat resistance to Fusarium graminearum by using cell wall-derived oligogalacturonides

Plant diseases cause substantial crop losses worldwide and compromise food safety because of the presence of toxins associated to fungal contamination. In addition to microbial diseases, climate changes negatively impact crop production as well as water and land availability for agriculture, while favoring pest distribution. Thus, sustainable yield increase, diminishing usage of chemicals and toxic compounds, enhancing crop resilience to biotic stress represent the main, concomitant, targets to be pursued in agriculture in the shortest period. Among the current approaches to crop protection, the use of elicitors, able to activate the natural defense mechanisms of the plant, as alternatives/complementary to pesticides and genetic resistances, is a strategy gaining increasing attention. Numerous studies indicate that local application of plant cell wall (CW)-derived elicitors, such as oligogalacturonides (OGs) derived from partial degradation of homogalacturonan, a major pectin component of the plant CW, induce broad-spectrum, long-lasting, and systemic resistance against pathogens in different plant species. The aim of this study was to establish the efficacy of OGs in protecting durum wheat, characterized by an extreme susceptibility to fusariosis caused by Fusarium graminearum. Our results demonstrate that OGs are indeed active elicitors of plant defenses in wheat triggering both a priming effect and the induction of typical immune marker genes, accompanied by the downregulation of genes involved in the fungus mycotoxins biosynthesis. No differences associated with growth and development of wheat seedlings were detected after elicitation with OGs. Furthermore, the study of durum wheat plants with potentially altered endogenous OG levels, i.e. OG-machine lines, is facilitating the elucidation of molecular mechanisms regulating plant defense activation upon sensing danger signals in cereals