Short-term resistance that persists: Rapidly induced silicon anti-herbivore defence affects carbon-based plant defences

1. Silicon (Si) is known to alleviate diverse biotic and abiotic stresses including insect herbivory. Si accumulation in plants, notably the Poaceae, can be induced through stimulation of the jasmonic acid (JA) pathway (associated with chewing herbivores). Nevertheless, the temporal dynamics of Si accumulation as a defence response and its consequential effects on carbon-based defences (e.g. phenolics), particularly in the short-term, remain unclear.

2. The model grass Brachypodium distachyon was grown in a hydroponic solution where half the plants were supplemented with 2 mM potassium silicate and half had no Si supplied. Plants were treated with methyl jasmonate (MeJA) as a form of standardised simulated herbivory. We measured Si accumulation, the phytohormones JA and salicylic acid (SA), and carbon-based defences over 24 hours to determine the temporal dynamics of Si accumulation and the interplay between Si, simulated herbivory and plant defence machinery.

3. MeJA-induced Si a...