Leaf damage by herbivores inNicotiana sylvestris Spegazzini and Comes (Solanaceae) produces a damage signal that dramatically increasesde 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, the speed with which different damage signals exit a damaged leaf can be studied. We propose that electrical damage signals should exit a leaf faster (less than 60 min) than chemical damage signals. Excision of a leaf induces a smaller increase in nicotine production than does puncture damage, so we examined our proposition by excising previously punctured leaves at 1, 60, and 960 min after leaf puncture and quantifying the induced whole-plant nicotine pools six days later when the induced nicotine production had reached a maximum. Significant induced nicotine production occurred only if punctured leaves were excised more than 1 hr after puncture, which is consistent with the characteristics of a slow-moving chemical signal rather than a fast-moving electrical signal. We explore the nature of the chemical signal and demonstrate that additions of 90microg or more of methyl jasmonate (MJ) in an aqueous solution to the roots of hydroponically grown plants inducede novo nicotine synthesis from(15)NO3 in a manner similar to that induced by leaf damage. We examine the hypothesis that jasmonic acid (JA) functions in the transfer of the damage signal from shoot to root. Using GC-MS techniques to quantify whole-plant JA pools, we demonstrate that leaf damage rapidly (<0.5 hr) increases shoot JA pools and, more slowly (<2 hr), root JA pools. JA levels subsequently decay to levels found in undamaged plants within 24 hr and 10 hr for shoots and roots, respectively. The addition of sufficient quantities (186microg) of MJ in a lanolin paste to leaves from hydroponically grown plants significantly increased endogenous root JA pools and increasedde novo nicotine synthesis in these plants. However, the addition of 93microg or less of MJ did not significantly increase endogenous root JA pools and did not significantly affectde novo nicotine synthesis. We propose 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.

中文翻译：

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伤口引起的根和枝条茉莉酸池的变化与 Nicotiana sylvestris spegazzini 中诱导的尼古丁合成相关联。

食草动物在烟草属 Spegazzini 和 Comes（茄科）中造成的叶片损伤会产生损伤信号，从而显着增加根部的尼古丁从头合成。合成的增加导致全植物尼古丁池的增加，这反过来又使植物更能抵抗食草动物的进一步攻击。由于信号产生和对信号的响应发生在广泛分离的组织中，因此可以研究不同损伤信号离开受损叶片的速度。我们建议电损伤信号应该比化学损伤信号更快（少于 60 分钟）离开叶子。与刺伤相比，切除一片叶子引起的尼古丁产量增加较小，因此我们通过切除先前刺破的叶子在 1、60、叶穿刺后 960 分钟，并在 6 天后当诱导的尼古丁产量达到最大值时量化诱导的全植物尼古丁池。只有在穿刺后超过 1 小时才切除被穿刺的叶子，才会发生显着的诱导尼古丁产生，这与缓慢移动的化学信号而不是快速移动的电信号的特征一致。我们探索了化学信号的性质，并证明在水溶液中向水培植物的根部添加 90 微克或更多的茉莉酸甲酯 (MJ) 诱导从 (15)NO3 以类似于诱导的方式从头合成尼古丁叶损伤。我们研究了茉莉酸 (JA) 在损伤信号从芽到根的转移中起作用的假设。使用 GC-MS 技术量化整株植物 JA 池，我们证明叶片损伤迅速（<0.5 小时）增加了芽 JA 池，更慢地（<2 小时）增加了根 JA 池。JA 水平随后分别在 24 小时和 10 小时内衰减到未受损植物中芽和根的水平。将羊毛脂糊中足量 (186 微克) 的 MJ 添加到水培植物的叶子中，显着增加了这些植物的内源根 JA 池并增加了尼古丁的从头合成。然而，添加 93microg 或更少的 MJ 并没有显着增加内源性根 JA 池，也没有显着影响从头尼古丁合成。我们建议伤害会增加枝条 JA 池，这可以直接通过运输或通过类似系统的信号间接增加根 JA 池，其中，