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

植物产生各种有毒和威慑性代谢产物以保护自己免受食草动物和病原体的侵害。在大多数物种中，诱导产生的化学防御是由研究充分的信号分子，特别是水杨酸和茉莉酸。然而，进化理论和最近的实验证据都表明，正如植物物种之间防御代谢物的产生存在巨大的多样性一样，植物用于防御信号的小分子也存在物种特异性变异。（Zea mays），世界上最重要的作物之一，丁博（2，4-二羟基-7-甲氧基-1，4-苯并恶嗪-3-酮）及其衍生物，统称为苯并恶嗪类化合物，构成了一类主要的防御相关化合物。除了其对食草动物和病原体的直接毒性外，丁布还需要诱导质外体胼胝质沉积，作为对韧皮部吸吮昆虫食草动物和真菌菌丝细胞间生长的防御。在通过苯并恶嗪类化合物进行代谢调节的另一个实例中，丁布及其分解产物可以扰乱生长素感知，从而直接影响植物生长和发育。为了研究DIMBOA和其他benzoxazinoids作为植物信号分子的重要性，我将提出两个主要的研究目标：1）我将研究玉米防御调节的以前未知的方面，不仅确定胼胝质上调的机制，而且还确定DIMBOA调节的其他防御反应。 2)我在博伊斯汤普森研究所和康奈尔大学的研究计划将结合联合收割机遗传学、基因组学、生物化学、生理学和生物信息学的方法。在我的宿主实验室中产生的玉米突变系，以及玉米自交系的自然变异，将使我能够研究DIMBOA作为体内和体外信号分子的调节功能。我对植物内部化学通讯的研究不仅将为调节防御诱导和生长的新型信号通路提供新的见解，而且还将使分子育种方法的实施能够产生具有天然增强的草食动物和病原体抗性的玉米。这个综合玉米研究项目，加上我将在我的东道主机构接受的其他培训，将使我为将来回到德国后在学术界的研究生涯做好充分准备。

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.