Molecular and metabolomics analysis reveals new insight into the mechanism underlying Iris halophila Pall. IhCHS1-mediated regulation of plant salt tolerance

Soil salinity represents a significant threat to agricultural productivity. The identification of salt response genes from halophytes is of great significance for improving the resistance of glycophytic crops to salt stress. Iris halophila Pall. is an important ornamental and medicinal halophyte that exhibits strong resistance to salt stress and is rich in flavonoids. Previously, transcriptome analysis revealed that chalcone synthase (CHS)-catalyzed flavonoid biosynthesis is involved in the response of I. halophila to high salt stress. However, the regulatory mechanism of CHS on plant metabolome under salt stress remains unclear. In this study, the function of IhCHS1 gene in regulating plant salt tolerance and metabolism was investigated. The results demonstrated that IhCHS1 was upregulated in I. halophila under salt stress. Transgenic Arabidopsis overexpressing IhCHS1 exhibited enhanced salt tolerance at both the seedling and mature stages. Physiological and metabolomic analysis indicated that the overexpression of IhCHS1 resulted in a reduction in the degree of membrane lipid peroxidation and an increase in proline content, antioxidant enzyme activities, and the abundance of several flavonoids and other phenylpropanoid compounds. Interestingly, IhCHS1 overexpression also significantly stimulated the accumulation of JA and IAA biosynthesis and signal transduction-related compounds, and altered the profiles of oligopeptides and nucleotide metabolites under salt stress. Our findings will provide new insight into the molecular mechanism of IhCHS1-mediated salt tolerance in plants and contribute to the development of strategies for cultivation of crop species with high salt tolerance and high metabolite accumulation on saline-alkali soil.