Biology Department, Mount Saint Vincent University, Halifax, NS, Canada.
Oecologia. 2010 Dec;164(4):1005-15. doi: 10.1007/s00442-010-1738-6. Epub 2010 Aug 5.
Tolerance to herbivory-the ability of plants to maintain fitness despite herbivore damage-is expected to change during the life cycle of plants because the physiological mechanisms underlying tolerance to herbivory are linked to growth, and resource allocation to growth changes throughout ontogeny. We used the model plant Arabidopsis thaliana to test two hypotheses: that tolerance increases as plants grow, and that tolerance decreases at the onset of reproduction. We chose three accessions previously reported to vary for resistance to herbivory in order to explore whether tolerance and resistance are inversely related. Cabbage looper (Trichoplusia ni) larvae were allowed to feed on plants at either the four-leaf, six-leaf, or 1st-flower developmental stage until 50% of the leaf area was removed. Overall, we found a trend for increased tolerance with ontogenetic stage, but there were important differences among accessions in their response to herbivory at different stages. Tolerance did not decrease with the onset of flowering, nor did we find any correlation between resistance and tolerance levels. Three main plant traits correlated strongly with tolerance: stem mass, an earlier onset of reproduction and a longer fruiting period. This study suggests there may be considerable variation in ontogenetic patterns of tolerance in natural populations of A. thaliana, and warrants further investigations with more accessions or natural populations, and detailed measurements of traits purported to contribute to tolerance in our quest to understand the mechanisms of tolerance to herbivory.
对草食性的耐受性——即植物在遭受草食动物损害时仍能保持适应能力的能力——预计会在植物的生命周期中发生变化，因为对草食性的耐受性的生理机制与生长有关，而资源分配到生长的变化贯穿个体发育。我们使用拟南芥作为模型植物来检验两个假设：一是植物在生长过程中耐受性会增加，二是在繁殖开始时耐受性会降低。我们选择了三个之前被报道在对草食性的抗性方面存在差异的品系，以探索耐受性和抗性是否呈负相关。小菜蛾（Trichoplusia ni）幼虫在四叶期、六叶期或第一朵花发育阶段被允许取食植物，直到叶片面积的 50%被去除。总的来说，我们发现随着个体发育阶段的增加，耐受性呈增加趋势，但在不同阶段对草食性的反应在不同品系之间存在重要差异。耐受性并没有随着开花的开始而降低，我们也没有发现抗性和耐受性之间存在任何相关性。三个主要的植物性状与耐受性密切相关：茎质量、较早的繁殖开始和较长的结实期。本研究表明，在拟南芥的自然种群中，对草食性的耐受性的个体发育模式可能存在相当大的差异，这需要进一步通过更多的品系或自然种群，以及对被认为有助于耐受性的性状进行详细测量，来进行研究，以了解对草食性的耐受性的机制。
