Silicon supplementation and jasmonate activation synergistically increase phenolic defences against a legume herbivore

The accumulation of silicon (Si) is widely reported to have anti-herbivore defensive properties in grasses. There is emerging, but fragmentary, evidence that Si could play a similar role in legumes. Here, we sought to understand the effects of Si supplementation on anti-herbivore defensive properties in lucerne (Medicago sativa), especially in relation to other potential defences (i.e. phenolics) and the phytohormone that regulates anti-herbivore defences, jasmonic acid or jasmonate (JA), which is also linked to Si accumulation. We determined how growth, root nodulation and chemistry (carbon, nitrogen and phenolic concentrations) of four genotypes of lucerne responded to Si supplementation, with and without the application of JA, and we used feeding assays to determine the subsequent effects on the feeding success of adult Sitona discoideus weevils. Si supplementation increased plant mass and root nodulation of M. sativa by 61% and 227%, respectively, and reduced relative consumption (R..., ,