Physiological and proteomic analysis reveal high recovery capacity of quinoa (Chenopodium quinoa Willd.) after progressive drought stress.

Quinoa, a resilient crop adapted to marginal environments, offers a promising alternative under water-limited conditions. To gain new insights into its drought tolerance, we combined physiological analyses with quantitative proteomics under progressive drought (1-2 weeks) and subsequent recovery (2 weeks). Drought stress induced significant reductions in biomass (56%) and relative water content (46%) after two weeks, with leaf osmotic potential decreasing by up to 48%. However, plants exhibited strong recovery in these parameters upon rehydration. Proteomic analysis identified 114 differentially abundant proteins between drought treatments and control. Proteins involved in cell defense and cytoskeleton organization including S-adenosylmethionine synthetase, caffeoyl-CoA O-methyltransferase, actin, and Exocyst complex component EXO84A, showed an increase under short-term drought conditions. Antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) increased during prolonged drought and further during recovery, while heat shock proteins (HSP90) accumulated under stress and declined after rewatering, supporting protein stability and oxidative defense. Multiple ribulose bisphosphate carboxylase large and small subunits (RuBisCO) showed increased abundance under drought and further increased during recovery, while oxygen-evolving enhancer proteins (OEE1, OEE2) accumulated early (D1W), helping to stabilize PSII under stress. Interestingly, key proteins involved in amino acid metabolism, including ACT domain-containing protein (ACR11), glutamine synthetase, and Ferredoxin-dependent glutamate synthase (Fd-GOGAT), were identified as regulators of nitrogen assimilation and oxidative stress regulation. Betaine aldehyde dehydrogenase was decreased under stress and increased during recovery, reflecting osmoprotectant accumulation. This study, integrating physiological and proteomic data, demonstrates that quinoa deploys immediate protective mechanisms while activating adaptive processes related to stress memory and recovery-associated metabolic changes, highlighting its resilience under water deficit.