LAUSR

Summary 1. Plants vary widely in the extent to which they defend themselves against herbivores. Because the resources available to plants are often site-specific, variation among sites dictates investment into defence, and may reveal a growth-defence trade-off. Moreover, plants that have evolved different life-history strategies in different environments may situate themselves on this trade-off curve differently. For instance, plants that flower later have a longer vegetative lifespan, and may accordingly defend themselves differently than those that flower earlier. 2. Here, we tested whether late-flowering plants, with a longer vegetative lifespan, invest more in defence than early-flowering plants, using recombinant genotypes of the annual herb Cardamine hirsuta that differ in flowering time as a result of differences in the activity of the major floral repressor Flowering Locus C (FLC). 3. We found that variation at FLC was mainly responsible for regulating flowering time and allocation to reproduction, but this partially depended on where the plants grew. We also found that variation at FLC mediated plant allocation to defence, with late- flowering plants producing higher levels of total glucosinolates and stress-related phytohormones. Nonetheless, plant growth and the qualitative values of plant defence and plant resistance against specialist herbivores were mainly independent from FLC. 4. Synthesis - Our results highlight pleiotropic effects associated with flowering-time genes that might influence plant defence and plant-herbivore interactions.