Krumm T, Bandemer K, Boland W
Institut für Organische Chemie und Biochemie, Bonn, Germany.
FEBS Lett. 1995 Dec 27;377(3):523-9. doi: 10.1016/0014-5793(95)01398-9.
One of the most intriguing plant defense reactions against herbivores is the emission of volatiles as potentially attractive signals for the natural enemies of the attacking species. Like many other low and high molecular weight chemical defenses, volatile production is under the control of the octadecanoid signalling pathway leading to jasmonic acid (2) (threshold concentration of jasmonic acid giving rise to volatile induction in Phaseolus lunatus: approximately 100 nmol.ml-1). A significantly more active compound is the phytotoxin coronatine (3) (threshold concentration: > or = 1 nmol.ml-1). Methyl esters of 1-oxo-indanoyl-isoleucine (4) or 1-oxo-indanoyl-leucine (5), designed as readily available analogues of coronatin (3), have also been shown to be active (threshold concentration: > or = 20 nmol.ml-1). Crucially, their component parts, i.e. 1-oxo-indan-carboxylic acid and the amino acids are completely inactive. The pattern of emitted volatiles, produced by plants treated with these analogues, is largely identical to that released from coronatine- or jasmonic acid-treated plants. While the reduction of the carbonyl group of jasmonic acid (2) results in an inactive molecule, namely curcurbic acid, the methyl ester of the 1-hydroxy-indanoyl-isoleucine conjugate (8) is at least as effective as the corresponding oxo-derivatives (4) and (5) (threshold concentration: > or = 20 nmol.ml-1). The results support the concept that epi-jasmonic acid (1) may be converted into a leucine or isoleucine conjugate at an early stage in the natural signal transduction pathway. Their later interaction with a macromolecular receptor apparently requires enolization of the carbonyl group in the jasmonate moiety, yielding a planar segment which is essential for successful binding with the macromolecule. The resulting hydroxy group is implicated in the formation of a hydrogen bond in the ensuing ligand/receptor complex.
植物针对食草动物的最有趣的防御反应之一是释放挥发性物质，作为对攻击物种天敌的潜在吸引信号。与许多其他低分子量和高分子量化学防御一样，挥发性物质的产生受导致茉莉酸的十八烷酸信号通路控制（菜豆中引起挥发性诱导的茉莉酸阈值浓度：约100 nmol·ml-1）。一种活性明显更高的化合物是植物毒素冠菌素（3）（阈值浓度：≥1 nmol·ml-1）。设计为冠菌素（3）易于获得的类似物的1-氧代茚甲酰异亮氨酸（4）或1-氧代茚甲酰亮氨酸（5）的甲酯也已被证明具有活性（阈值浓度：≥20 nmol·ml-1）。至关重要的是，它们的组成部分，即1-氧代茚甲酸和氨基酸完全没有活性。用这些类似物处理的植物释放的挥发性物质模式与用冠菌素或茉莉酸处理的植物释放的模式基本相同。虽然茉莉酸（2）的羰基还原会产生无活性的分子，即葫芦酸，但1-羟基茚甲酰异亮氨酸共轭物（8）的甲酯至少与相应的氧代衍生物（4）和（5）一样有效（阈值浓度：≥20 nmol·ml-1）。结果支持这样的概念，即表茉莉酸（1）可能在天然信号转导途径的早期阶段转化为亮氨酸或异亮氨酸共轭物。它们随后与大分子受体的相互作用显然需要茉莉酸部分中羰基的烯醇化，产生一个平面片段，这对于与大分子成功结合至关重要。产生的羟基参与随后的配体/受体复合物中氢键的形成。
