Huber Meret, Bont Zoe, Fricke Julia, Brillatz Théo, Aziz Zohra, Gershenzon Jonathan, Erb Matthias
Root Herbivore Interactions Group, Department of Biochemistry, Max Planck Institute for Chemical Ecology, Jena, Germany
Institute of Plant Sciences, University of Bern, Bern, Switzerland.
Proc Biol Sci. 2016 Mar 30;283(1827):20160285. doi: 10.1098/rspb.2016.0285.
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 recent 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表现出广泛的种内变异。然而，塑造这种多样性的选择压力往往仍然未知，尤其是在地下部分。我们以药用蒲公英及其主要本土食根昆虫大栗鳃金龟为研究对象，测试地下食草动物是否会驱动根次生代谢产物的种内变异。我们发现，近几十年来大栗鳃金龟的高侵染水平与21个中欧药用蒲公英田间种群中主要根乳胶次生代谢产物的高浓度有关。通过培育这些种群的后代，我们表明遗传变异和表型可塑性都导致了观察到的差异。此外，我们证明，在没有大栗鳃金龟的情况下，倍半萜内酯蒲公英酸β-D-吡喃葡萄糖酯（TA-G）的产生成本高昂，但在有大栗鳃金龟的情况下则有益，从而导致对TA-G的不同选择。我们的研究结果突出了土壤昆虫在植物自然防御进化中的作用。
