The jasmonate ZIM-domain (JAZ) proteins, known as inhibitors in the jasmonic acid (JA) pathway, have been reported to play a protective role against abiotic stress in plants. Nevertheless, the specific role of JAZ proteins in rice seedlings under alkaline stress remains unexplored. In this study, we mainly focus on OsJAZ10, investigating the physiological response mechanism and metabolic regulation on rice seedlings challenged by alkaline stress. Our results revealed that the antioxidant enzyme activity and osmotic adjustment ability of the OsJAZ10 overexpression lines were less affected by alkaline stress compared to WT (Wild-type) line. Metabolomic analysis demonstrated a significant accumulation of organic acids, including citrate and DL-malate, as well as amino acids such as DL-serine, DL-glutamine, threonine, glycine, and L-glutamate, in the OsJAZ10 overexpression plants in response to alkaline stress. Besides, OsJAZ10 was also involved in pantothenate and CoA biosynthesis, carbon fixation, and C5-branched dibasic acid metabolism in response to alkaline stress. Finally, OsJAZ10 was found to negatively regulated the biosynthesis and signaling of jasmonic acid pathway by repressing JA-responsive genes. Overall, this research elucidates the role of OsJAZ10 in conferring enhanced tolerance to alkaline stress in rice, providing valuable insights for the development of stress-tolerant rice varieties. OsJAZ10 potentially stimulates the accumulation of organic acids and amino acids by modulating of metabolism-assocoated genes in rice seedlings in response to alkaline stress.

The western part of north-eastern China is mostly covered by soda soil, which has a significant impact on the growth, breeding and production of crops. The present study investigates the physiological responses and metabolic adaptation of Chlamydomonas reinhardtii P.A.Dangeard (C. reinhardtii) under different types of alkaline stress and the potential application to soda soil improvement and plants in response to alkaline stress. The soda–saline soil was treated with C. reinhardtii for 5 and 120 days, respectively, and the chemical properties of the soil were determined. The microalga was cultured for a period of 12 days, with and without an alkaline medium, and then the metabolic profiles of the microalgae were then analyzed by metabolomics. Results showed that C. reinhardtii exhibited a high level of tolerance to 40 mM NaHCO₃, pH 8.3, and pH 10.3 with an increase in incubation time. Moreover, C. reinhardtii has been demonstrated to ameliorate selected physicochemical properties of soda–saline soil by reducing soil pH, electrical conductivity (EC), and the contents of CO₃²⁻ and HCO₃⁻ by 40–100% (w/w, wet biomass) addition for 120 cultivation days, respectively. It was demonstrated that rice seedlings were less affected by alkaline stress in the presence of C. reinhardtii. Furthermore, C. reinhardtii has the capacity to adapt to alkaline environments by regulating key pathways such as cofactor biosynthesis, glycerophospholipid metabolism, amino acid biosynthesis, purine metabolism, carbon metabolism, tropane, piperidine, and pyridine alkaloid biosynthesis. This adaptation is characterized by the accumulation of metabolites, including saccharides, amino acids and organic acids. These interact with high pH, CO₃²⁻ and HCO₃⁻ ions. This study elucidates that C. reinhardtii has the capacity to improve soda–saline soil and respond well to diverse alkaline stresses, attributable to its intricate metabolic profile.