Metal hyperaccumulation in plants: mechanisms of defence against insect herbivores
Metal hyperaccumulation in plants: mechanisms of defence against insect herbivores
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DOI：
10.1111/j.0269-8463.2005.00943.x
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发表时间：
2005-02-01
影响因子：
5.2
通讯作者：
Smith, JAC
中科院分区：
文献类型：
--
作者：
Behmer, ST;Lloyd, CM;Smith, JAC
1.为了确定金属在植物中的超积累可以提供对食草昆虫的化学防御的机制，研究了沙漠蝗Schistocerca gregaria（Forskal）在Thlaspi caerulescens J. & C. Presl含有不同的锌浓度，以及对人工食品的不同只是在锌含量.在选择实验中，蝗虫对T. Caerulescens植物含有低浓度的锌（平均值0.42毫克克（-1）干生物量）相比，中间（1.50毫克克（-1））或高（5.77毫克克（-1））锌浓度。在无选择实验中，蝗虫的第一餐持续时间没有差异，表明蝗虫不能直接品尝Zn，但总取食时间、取食量和蝗虫生长速率都随着叶面Zn浓度的增加而减少.当人工饲料中锌含量为0.5、1.5或5.5mg·g（-1）时，蝗虫取食中锌和高锌饲料的速度较慢，第四至第五龄期的发育时间相应较长。在第四体育场吃的食物总量是相似的不同的治疗，但蝗虫质量增益呈负相关的饮食中的锌浓度。这反映在蝗虫对高锌饲料的营养利用效率较低。在人工食物的选择实验中，蝗虫表现出与植物非常相似的摄食行为，消耗更多的低锌食物。实验使用香豆素调味的食物，有或没有锌，表明蝗虫对锌的厌恶是通过一种涉及联想学习的摄食后反馈机制发展起来的。这些结果支持的概念，金属在植物中的超积累可以提供一个防御昆虫食草动物，并表明，金属浓度本身可以解释高锌食品的威慑作用。锌浓度在0.5-5 mg/g（-1）范围内引起的厌恶反应，比通常在叶中观察到的要低一个数量级。青色的这表明，相对较小的海拔锌浓度可以赋予植物的适应性优势，通过影响多食性昆虫食草动物的摄食行为，从而有助于进化的金属超积累性状。
1. To determine the mechanisms by which metal hyperaccumulation in plants could provide a chemical defence against insect herbivores, the feeding behaviour and performance of the desert locust, Schistocerca gregaria (Forskal), was investigated on plants of Thlaspi caerulescens J. & C. Presl containing different zinc concentrations, as well as on artificial food differing only in Zn content.2. In choice experiments, locusts preferred T. caerulescens plants containing low foliar Zn concentrations (mean value 0.42 mg g(-1) dry biomass) compared with intermediate (1.50 mg g(-1)) or high (5.77 mg g(-1)) Zn concentrations. In no-choice experiments, there was no difference in the duration of the first meal, suggesting that locusts could not taste Zn directly, but total time spent feeding, amount of foliage eaten, and locust growth rate all decreased as foliar Zn concentration increased.3. When presented with artificial food containing Zn concentrations of 0.5, 1.5 or 5.5 mg g(-1), locusts fed at a slower rate on intermediate- and high-Zn diets, and their development time from fourth to fifth stadium was proportionately longer. The total amount of food eaten over the fourth stadium was similar for the different treatments, but locust mass gain was inversely related to Zn concentration in the diet. This was reflected in lower nutrient-utilization efficiencies in locusts on a high-Zn diet.4. In choice experiments with artificial food, locusts showed very similar feeding behaviour to that on plants, consuming more of the low-Zn food. Experiments using food flavoured with coumarin, provided with or without Zn, showed that the locusts' aversion to Zn develops by a post-ingestive feedback mechanism involving associative learning.5. These results support the notion that metal hyperaccumulation in plants can provide a defence against insect herbivores, and demonstrate that metal concentration per se can account for the deterrent effect of high-Zn foods. Aversion responses were evoked by Zn concentrations in the range 0.5-5 mg g(-1), an order of magnitude lower than those commonly observed in the foliage of T. caerulescens. This suggests that comparatively small elevations in Zn concentration could confer an adaptive advantage on plants by influencing the feeding behaviour of polyphagous insect herbivores, thereby contributing to evolution of the metal-hyperaccumulation trait.