Methyl Jasmonate Seed Priming Mitigates the Defence-Growth Trade-Off and Tailors Plant Response to Specific Pests

Seed defence priming is emerging as a novel, cost-efficient and environmentally safe tool for pest management. It has been proposed as a means to uncouple the defence-growth trade-off in plants by enhancing defence responses with minimal fitness costs, but the mechanisms underlying this role remain elusive. Here, we investigated seed priming as a mitigator of the compromise between growth and defence in Arabidopsis thaliana upon pest infestation, focusing on its molecular dynamics. After studying the effect of a set of seed priming agents on plant resistance and growth, and once an effective elicitor was identified, a combined -omics approach was employed to decipher the molecular mechanisms underlying that regulation. We found that seed priming with 0.1 mM methyl jasmonate effectively boosted plant defence with no obvious fitness penalty as a result of a fine-tune regulation between transcriptome and metabolome. The basal state of readiness of primed plants was characterized by reduced stomatal aperture, high transcriptomic variation, increased sugar content and enhanced translational rate. Upon pest infestation, primed plants exhibited herbivore-specific molecular responses, with the phenylpropanoid pathway showing particular relevance. These findings demonstrate that methyl jasmonate seed priming can enhance pest-tailored defences in plants without incurring any obvious fitness penalty.