Distinct metabolic signatures associated with drought response, shoot architecture, and flowering time in camelina

Camelina sativa is an ancient native oilseed species characterized by broad environmental adaptability, low-input requirements, and tolerance to multiple stresses. Its potential use in agroecological transition with double cropping systems could be improved by breeding a shorter life cycle. However, this strategy should not compromise its resilience to stresses as well as its metabolite profiles and plasticity. The impact of flowering time on drought stress response and seed quality was evaluated in six camelina edited mutants, carrying combinatory mutations on the flowering time genes SHORT VEGETATIVE PHASE, TERMINAL FLOWER 1, LIKE HETEROCHROMATIN PROTEIN 1, EARLY FLOWERING LOCUS 3, and FLOWERING LOCUS C and leading to a range of flowering precocity and shoot architecture changes. We characterized the phenotype of these mutants in response to early and late drought and showed that their flowering time was not strongly altered, contrary to branching and yield. Untargeted metabolomics demonstrated that, contrary to the lipidomic profile, the plasticity of the specialized metabolites was strongly modulated by drought in all genotypes. The specialized metabolite profile of the mutant seeds showed a distinct pattern in response to drought, with constitutive stress response of the bushy mutants in control conditions including differences in antioxidant content such as glutathione, isoquercetrin, and coumaroyl quinic acid. Metabolite profiling in leaves also showed specific metabolic signatures of some mutants but with lower metabolite diversity than in seeds. Including additional genotypes with distinct flowering times, we identified metabolites correlating with this trait, such as vitamin B2 and kynurenic acid in seeds. These metabolites could be used as predictive markers of flowering time.