Organosilicon enhances rice root suberization and antioxidant gene expression under cadmium/arsenic stress

Organosilicon exhibits unique physicochemical and biological properties with wide applicability across diverse fields, including agriculture and industry. Previous research has verified the effectiveness of organosilicon-modified fertilizers in inhibiting the uptake of cadmium (Cd) and arsenic (As) by plants. However, further investigations are necessary to elucidate the underlying mechanisms. In this study, we explored the potential of organosilicon to mitigate the toxic effects of Cd/As and lessen their uptake and accumulation during rice seed germination. Our results showed that under Cd/As stress, organosilicon treatments significantly increased suberin biosynthesis in rice roots. This was manifested as an increased level of root suberization and an enhanced apoplast barrier, as verified by observations made through fluorol yellow (FY) staining and transmission electron microscopy (TEM). Consequently, the uptake and translocation of Cd and As in rice seedlings were significantly reduced by 48.66 % and 72.19 % in shoots, and 43.23 % and 68.93 % in roots, respectively. Moreover, the application of organosilicon enhanced the activities of antioxidant enzymes in rice, This lead to an accelerated glutathione-oxidized glutathione (GSH-GSSG) cycle, up-regulated expression of the rice glutathione peroxidase gene (OsGPX), and increased GPX activity. These modifications effectively scavenged reactive oxygen species (ROS) generated by Cd/As stress and alleviated oxidative damage in rice. Overall, our study has unraveled the physiological and molecular mechanisms underlying the role of organosilicon in alleviating Cd/As toxicity in rice and has also provided new insights for the application of suberin in reducing heavy metal toxicity in plants.