Mr. Let Kho Hao

In nature, plants encounter various biotic and environmental stresses. In response to stress, plants produce specialized metabolites for their survival under hazardous environmental conditions and/or minimize herbivous insect attacks. Benzoxazinoids (BXDs) are one of the specialized metabolites produced by important cereal crops such as wheat, maize, and rye. These metabolites have broad functions in plant defense mechanisms, especially the methylated BXD compounds. Although the BXD pathway has been studied for decades mostly in maize, the genes involved in the biosynthesis pathway and their roles are not fully discovered in wheat. The main goal of the study is to reveal the unknown BXD biosynthetic genes (i.e., O-methyltransferase genes) in wheat and characterize their roles against combined stresses. I hypothesize that the wheat OMT genes are induced by biotic and abiotic stresses and are important for adjustment to stresses. Using network analysis with publicly available datasets, I generated a list of novel OMT candidate genes that potentially be involved in the BXD biosynthesis pathway in wheat. Using a Virus-Induced Gene Silencing (VIGS) system, the function of a candidate gene, BX7-like OMT, was validated in planta. The role of the candidate gene will be studied under a combination of biotic (aphids and caterpillar) and abiotic (drought and salinity) stresses using VIGS-silenced plants. Overall, this research will uncover the BXD biosynthesis pathway in wheat and provide broad impacts on the understanding of plants’ defense/resistance mechanisms against combined stresses that may contribute to wider plant breeding, promoting natural pesticides, and improving the sustainability of agricultural plants.