McCormick Andrea Clavijo, Boeckler G Andreas, Köllner Tobias G, Gershenzon Jonathan, Unsicker Sybille B
BMC Plant Biol. 2014 Nov 28;14:304. doi: 10.1186/s12870-014-0304-5.
The role of herbivore-induced plant volatiles as signals mediating the attraction of herbivore enemies is a well-known phenomenon. Studies with short-lived herbaceous plant species have shown that various biotic and abiotic factors can strongly affect the quantity, composition and timing of volatile emission dynamics. However, there is little knowledge on how these factors influence the volatile emission of long-lived woody perennials. The aim of this study was to investigate the temporal dynamics of herbivore-induced volatile emission of black poplar (Populus nigra) through several day-night cycles following the onset of herbivory. We also determined the influence of different herbivore species, caterpillars of the gypsy moth (Lymantria dispar) and poplar hawkmoth (Laothoe populi), and different herbivore developmental stages on emission.
The emission dynamics of major groups of volatile compounds differed strikingly in response to the timing of herbivory and the day-night cycle. The emission of aldoximes, salicyl aldehyde, and to a lesser extent, green leaf volatiles began shortly after herbivore attack and ceased quickly after herbivore removal, irrespective of the day-night cycle. However, the emission of most terpenes showed a more delayed reaction to the start and end of herbivory, and emission was significantly greater during the day compared to the night. The identity of the caterpillar species caused only slight changes in emission, but variation in developmental stage had a strong impact on volatile emission with early instar L. dispar inducing more nitrogenous volatiles and terpenoids than late instar caterpillars of the same species.
The results indicate that only a few of the many herbivore-induced black poplar volatiles are released in tight correlation with the timing of herbivory. These may represent the most reliable cues for herbivore enemies and, interestingly, have been shown in a recent study to be the best attractants for an herbivore enemy that parasitizes gypsy moth larvae feeding on black poplar.
植食性动物诱导植物释放挥发性物质作为介导吸引植食性动物天敌的信号，这是一个众所周知的现象。对短命草本植物物种的研究表明，各种生物和非生物因素会强烈影响挥发性物质释放动态的数量、组成和时间。然而，关于这些因素如何影响长寿木本多年生植物的挥发性物质释放，人们了解甚少。本研究的目的是在食草作用开始后的几个昼夜周期内，研究食草动物诱导的黑杨（Populus nigra）挥发性物质释放的时间动态。我们还确定了不同食草动物物种（舞毒蛾（Lymantria dispar）和杨树天蛾（Laothoe populi）的毛虫）以及不同食草动物发育阶段对挥发性物质释放的影响。
主要挥发性化合物组的释放动态对食草时间和昼夜周期的响应差异显著。醛肟、水杨醛以及程度较轻的绿叶挥发性物质在食草动物攻击后不久开始释放，在食草动物移除后迅速停止，与昼夜周期无关。然而，大多数萜类化合物的释放在食草作用开始和结束时反应更为延迟，并且白天的释放量明显高于夜间。毛虫物种的身份仅导致释放量有轻微变化，但发育阶段的差异对挥发性物质释放有强烈影响，同一物种的低龄舞毒蛾幼虫比高龄幼虫诱导产生更多含氮挥发性物质和萜类化合物。
结果表明，在许多食草动物诱导的黑杨挥发性物质中，只有少数几种与食草时间紧密相关地释放。这些可能是植食性动物天敌最可靠的线索，有趣的是，最近的一项研究表明，这些物质是寄生在以黑杨为食的舞毒蛾幼虫上的一种植食性动物天敌的最佳引诱剂。
