Physiological, cytological and multi-omics analysis revealed the molecular response of Iris domestica to Cd toxicity (PRJCA028981)

Iris domestica, a rhizomatous perennial in the Iridaceae family, exhibits a high degree of resistance to various abiotic stress. However, the molecular mechanism of I. domestica facing escalating cadmium (Cd) stress has not yet been reported. This study combined physiological, cytological, and multi-omics analyses to explore the toxic effects of Cd stress and detoxification mechanisms of I. domestica. The results demonstrated that Cd stress could reduce the contents of photosynthetic pigment, activate antioxidant activity, and inhibit the plant growth and development. Transport factor revealed that this plant has a stronger Cd transport capability. Transmission electron microscopy revealed that Cd stress could damaged the cell ultrastructure in roots and leaves indicated by swollen chloroplasts and deformed cell walls. Additionally, the transcriptome and metabolome revealed that Cd stress mainly influenced three pathways, namely plant hormone signal transduction, glutathione metabolism, and phenylpropanoid biosynthesis. Moreover, 6,351 differentially expressed genes (DEGs, 1,429 upregulated and 4,915 downregulated) and 2,546 differentially expressed genes (DEGs, 1,605 upregulated and 941 downregulated) were identified in roots and leaves via RNA-seg among two Cd treatments, respectively. Meanwhile, conjoint analysis found several DEGs and DEMs are associated with plant hormone signal transduction, cell wall biosynthesis, glutathione and flavonoid, implying that these pathways plays essential roles in Cd uptake and detoxification. In addition, ion transport proteins were signifcantly induced by Cd stress, especially IdNRAMP2. Overexpression (OE) of IdNRAMP2 can enhance the transportation of Cd from roots to aboveground in transgenic plants, increased the activities of SOD, POD, and CAT, and decreased the contents of MDA and H2O2 to enhance the scavenging capacity of plants to ROS. Our comprehensive investigation using multiple approaches provides a molecular-scale perspective on plant response to Cd stress.