Regulation of herbivore-induced defenses responses by benzoxazinoids in Zea mays

点击翻译按钮获取中文摘要

Plants produce a wide variety of toxic and deterrent metabolites to protect themselves against herbivores and pathogens. In most species, the inducible production of chemical defenses is regulated by well-studied signaling molecules, in particular, salicylic acid and jasmonic acid. However, both evolutionary theory and recent experimental evidence suggest that, just as there is great diversity in the production of defensive metabolites among plant species, there is also species-specific variation in the small molecules that plants implement for defense signaling.In maize (Zea mays), one of the world’s most important crop plants, DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) and its derivatives, collectively called benzoxazinoids, constitute a major class of defense-related compounds. In addition to its direct toxicity against herbivores and pathogens, DIMBOA is required for inducing apoplastic callose deposition as a defense against both feeding by phloem-sucking insect herbivores and intercellular growth of fungal hyphae. In a further example of metabolic regulation by benzoxazinoids, DIMBOA and its breakdown products can perturb auxin perception, thereby directly influencing plant growth and development. To investigate the importance of DIMBOA and other benzoxazinoids as plant signaling molecules, I will address two main research objectives: 1) I will investigate previously unknown aspects of maize defense regulation, identifying not only the mechanism of callose up-regulation, but also other defense responses that are regulated by DIMBOA. 2) I will examine the interactions between DIMBOA and auxin at the molecular level, thereby identifying new regulatory connections between plant defense and development.My proposed research program at the Boyce Thompson Institute and Cornell University will combine genetic, genomic, biochemical, physiological, and bioinformatics methods. Maize mutant lines generated in my host lab, as well as natural variation in maize inbred lines, will allow me to investigate regulatory functions of DIMBOA as a signaling molecule in vivo and in vitro. My investigation of chemical communication within plants not only will provide new insights into novel signaling pathways that regulate both defense induction and growth, but also will enable the implementation of molecular breeding approaches to produce maize with naturally enhanced herbivore and pathogen resistance. This integrated maize research program, together with other training that I will receive at my host institution, will make me well-prepared for a future research career in academia when I return to Germany.