Balancing growth and resilience: A multi-omics study of chickpea's intergenerational adaptive strategies under drought stress

Abiotic stress events associated to climate change are still a critical challenge to crop productivity. Particularly, drought is an emergency even for legumes, such as chickpea, growing in arid regions. The present study aims to shed light into the complex and hidden mechanisms of intergenerational memory to drought stress using a multi-omics approach, encompassing RNA-seq, WGBSeq and metabolomic analysis with biochemical, morphological and phenotypic analysis. Significant memory effects were observed across several evaluated morphological traits and biochemical stress parameters. We provided evidence that the drought stress occurring at the parental stage modulated key phenotypic and physiological parameters, making offspring better adapted for future stress events, but reducing their fitness under optimal irrigation conditions. Stress memory impacted specific leaf area (SLA), photosynthesis rates and plant biomass, aligning with a conservative growth strategy which prioritizes stress responses inducing better resilience rather than growth. A pronounced memory effect was also detected in reactive oxygen species (ROS) scavenging mechanisms, which significantly increased in the offspring of stressed parents (G1S) compared to those of control parents (G1C). In addition, G1S exhibited upregulation of oxidoreductase related genes, while offspring from G1C favored the expression of genes related to proline biosynthesis. This suggests memory mechanisms that lead to different drought stress strategies. The intergenerational memory also affected DNA methylation as shown by fewer differently methylated genes (DMGs) in response to drought stress in G1S compared to G1C. In addition, when comparing stress to control condition, both parental plants and offspring from well-watered parental plants significantly reduced the percentage of genome-wide methylations, whereas the filial generation of stressed parents showed higher DNA methylation rates. Metabolic profiling further highlighted the impact of drought stress recurrence evidencing distinct metabolite profiles in plants derived by different parental stress conditions. Key drought stress-related metabolites (proline, tryptophan, alanine, fructose) were particularly affected by a second stress exposure implying that the memory has also a profound effect at metabolism level. Our findings provide valuable insight into the complex mechanisms governing intergenerational plant stress memory and provide ground for applications to develop climatesmart legume varieties using sustainable biotechnological approaches.