Data from: A below ground herbivore shapes root defensive chemistry in natural plant populations

Plants display extensive intraspecific variation in secondary metabolites. However, the selective forces shaping this diversity remain often unknown, especially below ground. Using Taraxacum officinale and its major native insect root herbivore Melolontha melolontha, we tested whether below ground herbivores drive intraspecific variation in root secondary metabolites. We found that high M. melolontha infestation levels over the last decades are associated with high concentrations of major root latex secondary metabolites across 21 central European T. officinale field populations. By cultivating offspring of these populations, we show that both heritable variation and phenotypic plasticity contribute to the observed differences. Furthermore, we demonstrate that the production of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G) is costly in the absence, but beneficial in the presence of M. melolontha, resulting in divergent selection of TA-G. Our results highlight the role of soil-dwelling insects for the evolution of plant defences in nature.

植物在次生代谢产物方面存在广泛的种内变异。然而，塑造这种多样性的选择压力往往仍不明确，在地下环境中尤其如此。本研究以西洋蒲公英（Taraxacum officinale）及其本土主要根食性昆虫欧洲鳃金龟（Melolontha melolontha）为研究对象，探究地下植食性昆虫是否会驱动植物根次生代谢产物的种内变异。我们发现，在过去数十年间，欧洲鳃金龟的高侵染水平与中欧21个西洋蒲公英野外种群中根乳汁中的主要次生代谢产物高含量呈显著关联。通过培育这些种群的子代，我们证实遗传变异与表型可塑性共同导致了观测到的差异。此外，我们证实，在无欧洲鳃金龟存在时，倍半萜内酯类化合物蒲公英酸β-D-吡喃葡萄糖酯（taraxinic acid β-D-glucopyranosyl ester，TA-G）的合成存在适应性代价，但在有该昆虫存在时则具有适应性益处，由此导致TA-G受到歧化选择。本研究结果凸显了栖土昆虫在自然界植物防御演化过程中的重要作用。