Genomics-Driven Discovery of Clustered Biosynthetic Pathways for Defense-Related Molecules in Bread Wheat

Wheat is one of the most widely grown crops in the world and accounts for 20% of human caloric intake, but is under constant threat from numerous pests and diseases that lead to annual losses of a fifth of global wheat production. A better mechanistic understanding of wheat defense response against biotic stress is thus of major importance. However, current knowledge of the chemical defenses induced in wheat in response to pathogen infection remains very limited. The recent assembly of the bread wheat genome has brought unprecedented opportunities for investigating pathogen-induced biosynthetic pathways and their products in wheat, so providing insights into its chemical arsenal. Using a genomics-driven approach we discovered six previously unknown pathogen-induced biosynthetic pathways in wheat, which share a common regulatory network and form part of an orchestrated defense response. Investigation of these pathways revealed that they are each encoded by biosynthetic gene clusters (BGCs), which produce a diverse set of molecules- including flavonoids, diterpenes and triterpenes. These findings exemplify the power of transcriptional networks for rapid discovery of defense-related molecules in plants and provide key insights into the molecular basis of biotic stress responses in wheat.