Foliar jasmonic acid application reduces Cd and As accumulations in rice grains by regulating physiological, biochemical, and ROS scavenging attributes

Abstract

The remediation of soil contaminated with cadmium (Cd) and arsenic (As) has consistently been a complex issue. Foliar application of jasmonic acid (JA) could be a promising agronomic practice for reducing heavy metal accumulations. However, the combined reduction effects and mechanisms of Cd and As in rice through foliar JA application have not been fully explored. In this study, a pot experiment was conducted to investigate rice yield, Cd and As accumulations and translocations, photosynthesis, and ROS-scavenging attributes in Huanghuazhan (HHZ) and Huarun No.2 (HR). The results revealed that 1 μM JA treatment significantly decreased the concentrations of Cd (by 34.6% in HHZ and 38.3% in HR) and As (by 30.8% in HHZ and 40.8% in HR) in the grains, and increased the percentage of filled-grain and 1000-grain weight in HHZ. The structural equation model (SEM) indicated that grain Cd was directly and positively affected by panicle Cd and leaf sheath Cd, while grain As was directly and positively affected by panicle As, leaf blade As and leaf sheath As. JA application enhanced the net photosynthetic rate and chlorophyll content (both a and b). Additionally, it scavenged levels of H2O2 and O2.-, reduced lipid peroxidation damage by promoting the activities of antioxidant enzymes and altering the cellular redox status in the flag leaves of rice. Overall, these results suggest that foliar JA application of could be an effective strategy for preventing Cd and As accumulations in rice grains in paddy soils with low to medium contamination risks.