The formation and regulation of benzoxazinoids as important defense compounds in wheat

• Applicant: Dr. Tobias Gerhardt Köllner
• Subject Area: Plant Biochemistry and Biophysics
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461126932

Plants in nature are continuously attacked by insects and, in response, produce different defenses to reduce damage and maintain their own fitness. Nonetheless, insect herbivory often causes severe damage to plants, especially when grown in large monocultures, and this damage can result in significant yield losses. It is therefore of the utmost importance to rigorously explore natural plant defense mechanisms and traits in order to discover additional resistance mechanisms that can be deployed against insect herbivores and other pests.Benzoxazinoids represent a class of specialized plant metabolites and play important roles in plant defense. They are abundant in many species of the Poaceae, including such important crops as maize, wheat, and rye. The formation of the benzoxazinoid backbone has been intensively investigated in maize and comprises eight enzymatic steps. The formed compound, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc), can be further converted by a number of recently identified enzymes into other benzoxazinoids. While the core pathway is conserved among the grasses, enzymes involved in the decoration of the benzoxazinoid backbone have been independently evolved in single species. Although these decorations mainly determine the specific biological activities of individual benzoxazinoids, little is known about their biochemistry in other species than maize. Moreover, the mechanisms that regulate the core benzoxazinoid pathway and the decorating enzymes are poorly understood. In the proposed project, we will combine genetic methods such as quantitative trait loci mapping and the generation and characterization of introgression lines with high-throughput metabolite analysis to identify genes involved in the formation and regulation of benzoxazinoids in the important crop grass wheat. Candidate enzymes and transcription factors will be characterized in vitro using heterologous expression and Chip-Seq analysis, respectively. Transient gene silencing and stable overexpression of candidate genes in wheat will help to elucidate their roles in planta. Moreover, bioassays with aphids and caterpillars will be performed to study the biological consequences of altered BXD profiles in transgenic plants. The expected results will promote future efforts to improve plant resistance and in consequence can help to ultimately reduce our reliance on harmful pesticides.The project will last 36 months and will allow to initiate and intensify an international collaboration between three working groups from the Max Planck Institute for Chemical Ecology (Germany), the Ben-Gurion-University of the Negev (Israel), and the University of Haifa (Israel). All groups have experiences with previous international collaborations and their complementary skills and interests in wheat genetics, plant biochemistry, and plant-insect interactions ensure the overall success of the project.

• DFG Programme: Research Grants
• International Connection: Israel
• International Co-Applicants: Professor Dr. Assaf Distelfeld; Dr. Vered Tzin