Osier Tod L, Lindroth Richard L
Department of Entomology, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI 53706, USA.
Oecologia. 2006 Jun;148(2):293-303. doi: 10.1007/s00442-006-0373-8. Epub 2006 Feb 9.
Although genetic variability and resource availability both influence plant chemical composition, little is known about how these factors interact to modulate costs of resistance, expressed as negative correlations between growth and defense. We evaluated genotype x environment effects on foliar chemistry and growth of quaking aspen (Populus tremuloides) by growing multiple aspen genotypes under variable conditions of light and soil nutrient availability in a common garden. Foliage was analyzed for levels of nitrogen, phenolic glycosides and condensed tannins. Bioassays of leaf quality were conducted with fourth-stadium gypsy moth (Lymantria dispar) larvae. Results revealed strong effects of plant genotype, light availability and nutrient availability; the importance of each factor depended upon compound type. For example, tannin concentrations differed little among genotypes and across nutrient regimes under low light conditions, but markedly so under high light conditions. Phenolic glycoside concentrations, in contrast, were largely determined by genotype. Variation in phenolic glycoside concentrations among genotypes was the most important factor affecting gypsy moth performance. Gypsy moth biomass and development time were negatively and positively correlated, respectively, with phenolic glycoside levels. Allocation to phenolic glycosides appeared to be costly in terms of growth, but only under resource-limiting conditions. Context-dependent trade-offs help to explain why costs of allocation to resistance are often difficult to demonstrate.
尽管遗传变异性和资源可用性都会影响植物的化学成分，但对于这些因素如何相互作用以调节抗性成本（表现为生长与防御之间的负相关），我们却知之甚少。我们通过在一个共同花园中，在光照和土壤养分可用性的可变条件下种植多种白杨基因型，评估了基因型×环境对颤杨（Populus tremuloides）叶片化学组成和生长的影响。分析了叶片中的氮、酚类糖苷和缩合单宁水平。用四龄舞毒蛾（Lymantria dispar）幼虫进行了叶片质量的生物测定。结果显示了植物基因型、光照可用性和养分可用性的强烈影响；每个因素的重要性取决于化合物类型。例如，在低光照条件下，基因型之间以及不同养分处理下的单宁浓度差异不大，但在高光照条件下差异明显。相比之下，酚类糖苷浓度在很大程度上由基因型决定。基因型间酚类糖苷浓度的变化是影响舞毒蛾性能的最重要因素。舞毒蛾的生物量和发育时间分别与酚类糖苷水平呈负相关和正相关。就生长而言，分配到酚类糖苷似乎是有代价的，但仅在资源有限的条件下如此。上下文依赖的权衡有助于解释为什么分配给抗性的成本往往难以证明。
