Transgenerational Drought and Methyl Jasmonate Memory Interactively Shape Metabolome and Physiology in Clonal Grass.

As droughts become more common due to climate change, plant survival may rely not only on its immediate response but also on what it has learned from past challenges. However, we still know little about how plants integrate different types of experiences, such as recurrent drought and hormonal cues, from previous generations. In this study, we examined whether clonal offspring of a grass species, Festuca rubra, previously exposed to drought, stress hormone methyl jasmonate (MeJA), or their combination inherited biological memories that help them tolerate new drought stress. We combined untargeted LC-MS metabolomics with morpho-physiological measurements to evaluate these memory effects. We found that each type of memory changed plant metabolism and physiology, but the most notable changes occurred when both memories were present, and plants faced recurrent drought conditions again. This interaction between drought memory, MeJA memory, and current stress did not just add effects; it created entirely new metabolic responses, not seen in any single treatment. These combined memories fine-tuned water conservation, photosynthesis, and extensive metabolomic reshuffling, revealing a deeper level of drought resilience. Our results uncover a layered memory system in plants where past stresses do not act in isolation but interact to reshape future responses. This offers new insight into how plants prepare for stress and suggests practical strategies for priming drought tolerance across plant generations.