Chemical Ecology of Jasmonates as Signals for an Inducible Defense

烟草植物（Nicotiana sylvestris, Solanaceae）的叶片受到草食动物的伤害，会产生一个损伤信号，显著增加根系中尼古丁的新生合成。合成的增加导致整个植物尼古丁库的增加，这反过来又使植物更能抵抗食草动物的进一步攻击。由于信号的产生和对信号的反应发生在广泛分离的组织中，这种全植物诱导的防御是研究信号转导级联以及生物和非生物环境如何影响这种诱导防御的理想系统。研究表明，损伤信号具有韧皮部传输的缓慢移动的化学信号特征，而十八烷衍生物环戊酮茉莉酸（jasmonic acid， JA）是这种诱导防御中损伤信号转导途径的重要组成部分。在这个项目中，Baldwin博士将严格检验伤害增加茎JA池的假设，这一假设直接通过运输或间接通过系统样信号增加根JA池，这反过来刺激根尼古丁合成并增加整个植物的尼古丁池。为了实现这一目标，Baldwin博士将确定茎和根中诱导的茉莉酸池的手性，检查植物对十八烷酸途径中中间体的尼古丁反应，并合成天然立体构型的茉莉酸盐。通过了解信号产生和传输的过程，我们有可能了解食草动物是如何“偷偷地”消耗植物的，并明显减少由它们的摄食激活的诱导防御。

9507180 Baldwin Leaf damage by herbivores in Nicotiana sylvestris (Solanaceae) produces a damage signal which dramatically increases de novo nicotine synthesis in the roots. The increased synthesis leads to increases in whole-plant nicotine pools, which in turn make plants more resistant to further herbivore attack. Because signal production and the response to the signal occur in widely separated tissues, this whole-plant induced defense represents an ideal system in which to study the signal transduction cascade and how the biotic and abiotic environment influence this induced defense. It has been demonstrated that the damage signal has the characteristics of a slow-moving phloem-transported chemical cue and that jasmonic acid (JA), an octadecanoid- derived cyclopentanone, is an important component of the damage signal transduction pathway in this induced defense. In this project Dr. Baldwin will critically examine the hypothesis that wounding increases shoot JA pools which either directly through transport or indirectly through a systemin-like signal increase root JA pools, which, in turn stimulate root nicotine synthesis and increase whole-plant nicotine pools. To achieve this objective Dr. Baldwin will determine the chirality of the induced jasmonate pools in shoot and roots, examine the plant's nicotine responses to intermediates in the octadecanoid pathway and synthesize jasmonates in the native stereoconfigurations. By understanding the processes responsible for signal generation and transport it may be possible to understand how herbivores consume plants "stealthily" and apparently lessen the induced defenses activated by their feeding.