Integrated transcriptomics and metabolomics reveal key metabolic pathway responses in Iris tectorum under chromium stress

Chromium (Cr) induces molecular alterations, disrupts metabolites, and impedes plant growth, necessitating the elucidation of the molecular stress mechanism underlying Cr tolerance in plants to evaluate the enduring environmental effects of Cr stress. In this study, I. tectorum was employed as the experimental model to scrutinize Cr accumulation and transport, along with physiological alterations in antioxidants, metabolites, and functional genes in plants under Cr stress. The findings exhibited a significant reduction in plant biomass under Cr stress, accompanied by pronounced enhancements in Cr enrichment capacity and homeostatic oxidative stress ability. Metabolomic analysis revealed that Cr stress primarily affected nine metabolic pathways in I. tectorum, involving 25 differentially expressed metabolites (DEMs), predominantly comprising fatty acids, terpenoids, flavonoids, phenylpropanoids, and organic acids. In addition, the transcriptomic analysis identified a total of 19,136 differentially expressed genes (11994 up-regulated and 7142 down-regulated DEGs) across the three comparison groups. These DEGs were primarily associated with cell wall biosynthesis, oxidative stress response, signal transduction, and plant carbohydrate metabolism pathways. A comprehensive analysis unveiled the pivotal roles of the cell wall biosynthetic pathway and the oxidative stress system in I. tectorum for Cr detoxification. In conclusion, this study encompassed a comprehensive investigation utilizing diverse methodologies to unravel the molecular detoxification mechanism employed by I. tectorum, a wetland plant, in combating Cr stress.