Chemical Ecology of Jasmonates as Signals for an Inducible Defense

9507180烟草(茄科)中食草动物对鲍德温叶片的伤害产生了一种伤害信号，极大地增加了根部尼古丁的从头合成。合成的增加导致全植物尼古丁库的增加，这反过来又使植物对进一步的食草动物攻击更具抵抗力。由于信号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运输缓慢的化学信号特征，茉莉酸(JA)是由十八烷类化合物衍生的环戊酮，是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博士将批判性地检验这一假说，即伤害增加了地上部JA库，无论是直接通过运输还是间接通过系统素样信号增加了根JA库，这反过来又刺激了根尼古丁的合成，增加了全植物尼古丁库。为了实现这一目标，鲍德温博士将确定在茎和根中诱导的茉莉酸库的手性，检查植物对十八烷类途径中间体的尼古丁反应，并在原生构型中合成茉莉酸酯。通过了解负责信号产生和传输的过程，或许可以理解草食动物如何“偷偷”消耗植物，并明显减少它们取食激活的诱导防御。

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.