Abstract Water availability is an important factor that influences plant-insect interactions. While the influence of water limitation on plant resistance traits has received much attention, how water availability affects plant tolerance to herbivory is rarely tested. Here we show that lower water availability reduced tolerance capacity of tomato plants as measured by above ground regrowth and flower development after herbivory. In contrast to a reduced ability to tolerate herbivory, lower water availability increased the constitutive and induced levels of two defensive proteins, trypsin protease inhibitor and polyphenol oxidase, indicative of an increased investment on resistance under water limitation. The increase in defense proteins was paralleled with lower performance of a specialist caterpillar, Manduca sexta, and lower consumption of plant tissues. Although the performance of generalist, Helicoverpa zea, was unaffected by water availability, we observed a high mortality of H. zea that suggests strong resistance of tomato against H. zea. The findings revealed an unexpected case where water limitation decreases tolerance but increases resistance of a plant, suggesting a potential tradeoff between these strategies. This plasticity may benefit herbaceous plants by balancing growth and defense under variable water availability.

中文翻译：

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可变水源下植物对昆虫食草动物的耐受性和抗性的变化

摘要 水的可用性是影响植物-昆虫相互作用的重要因素。虽然水分限制对植物抗性性状的影响受到了很多关注，但很少测试水分可用性如何影响植物对食草性的耐受性。在这里，我们表明，通过食草后的地上再生和花发育来衡量，较低的可用水会降低番茄植物的耐受能力。与耐受食草动物的能力降低相反，较低的水可用性增加了两种防御性蛋白质、胰蛋白酶蛋白酶抑制剂和多酚氧化酶的组成和诱导水平，表明在水分限制下对抵抗力的投资增加。防御蛋白的增加与专业毛毛虫 Manduca sexta 的性能降低相平行，并减少植物组织的消耗。虽然通才 Helicoverpa zea 的性能不受水可用性的影响，但我们观察到 H. zea 的高死亡率，这表明番茄对 H. zea 有很强的抵抗力。研究结果揭示了一个意想不到的案例，即水分限制会降低植物的耐受性，但会增加植物的抗性，这表明这些策略之间存在潜在的权衡。这种可塑性可以通过在可变的水可用性下平衡生长和防御来使草本植物受益。建议在这些策略之间进行潜在的权衡。这种可塑性可以通过在可变的水可用性下平衡生长和防御来使草本植物受益。建议在这些策略之间进行潜在的权衡。这种可塑性可以通过在可变水供应下平衡生长和防御来使草本植物受益。