Signal Transduction Pathways for Inducible Plant Defense Genes

研究植物叶片防御性蛋白酶抑制剂蛋白合成的细胞内信号转导途径。我们以前的研究提供了强有力的证据表明，在番茄，马铃薯和苜蓿植物中调节两种蛋白酶抑制剂基因的诱导信号通路，以及可能在其他植物中，涉及一个基于脂质的系统，导致茉莉酸作为关键信号分子的产生。有证据表明，昆虫或病原体的攻击产生细胞外信号，与植物细胞膜相互作用，释放亚麻酸。已知亚麻酸通过几个生化步骤转化为茉莉酸。亚麻酸和茉莉酸都是强有力的诱导剂的抑制基因时，放置在叶表面，表明它们参与的信号通路。这项研究将寻求植物膜内释放亚麻酸以响应昆虫或病原体攻击产生的信号的机制，并将建立导致茉莉酸合成的生化事件。茉莉酸可激活植物细胞核中蛋白酶抑制剂基因表达的机制也将被研究。将寻求茉莉酸及其受体的命运，并研究其在基因激活中的作用。这些信息将用于了解诱导植物防御昆虫和病原体的生化基础。

Research is proposed to investigate the intracellular signal transduction pathways that regulate the synthesis of defensive proteinase inhibitor proteins in plant leaves in response to herbivore and pathogen attacks. Our previous research has provided strong evidence that the inducible signalling pathways that regulate two proteinase inhibitor genes in tomato, potato, and alfalfa plants, and likely in other plants as well, involve a lipid-based system that results in the production of jasmonic acid as a key signalling molecule. The evidence suggests that insect or pathogen attacks produce extracellular signals that interact with the plant cell membrane to release linolenic acid. Linolenic acid is known to be converted to jasmonic acid through several biochemical steps. Both linolenic acid and jasmonic acid are powerful inducers of the inhibitor genes when placed on leaf surfaces, indicating their involvement in the signalling pathway. The research funded by this grant will seek the mechanism within the plant membranes that releases linolenic acid in response to signals produced by insect or pathogen attacks and will establish the biochemical events leading to the synthesis of jasmonic acid. The mechanism by which jasmonic acid can activate proteinase inhibitor gene expression in the plant cell nucleus will also be studied. The fate of jasmonic acid and its receptor will be sought, and its role in gene activation will be investigated. The information will be utilized to understand the biochemical basis of inducible plant defenses against insects and pathogens.