Integrated transcriptome and metabolomics analysis revealed the molecular response mechanism of iris tectorum under chromium stress

The molecular stress mechanisms of chromium(Cr) tolerance in plants is elucidated in order to assess the persistent environmental effects of chromium stress. In this study, I. tectorum was employed as the experimental model to scrutinize Cr accumulation and transportation, along with physiological alterations including 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). 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 to unravel the molecular detoxification mechanism employed by I. tectorum, a wetland plant, in combating Cr stress utilizing diverse methodologies. Cr stress inhibited the biosynthesis of photosynthetic pigments. Cr stress increased the content of GSH and the activities of SOD, POD and APX. Cr stress increased ROS and MDA contents in plants. Cr stress increases the contents of metabolites of Flavonoids and Phenylpropanoids. Cell wall biosynthesis and oxidative stress are the key stress mechanisms.