Putrescine modulates cadmium fixation ability of the cell wall to decrease cadmium accumulation in rice via a NO dependent manner

Abstract

Abstract Although putrescine (PUT) has been linked to plants' responses to cadmium (Cd) stress, the exact mechanism is yet elusive. The endogenous PUT concentration in the rice roots was enhanced by Cd stress in the current investigation, and exogenous PUT increased root cell wall hemicellulose level, which in turn increased its Cd binding capacity, concurrently decreasing the transcription level of genes such as Natural Resistance-Associated Macrophage Protein 1 (OsNRAMP1) and a major facilitator superfamily gene-OsCd1 that responsible for root Cd absorption. Finally, less Cd was accumulated in the rice as a result of the higher expression of Heavy Metal ATPase 3 (OsHMA3), and Cation/Ca exchanger 2 (OsCCX2) that were responsible for separating Cd into vacuole and getting Cd out of cells, respectively. Additionally, PUT enhanced endogenous NO levels, and its alleviatory effect was disappeared by a NO scavenger-cPTIO. In conclusion, PUT enhanced rice’s Cd resistance through regulating the generation of the NO and the binding capacity of the cell wall to Cd.