Synergistic interaction between brassinosteroid and jasmonate pathways in rice response to cadmium toxicity

Brassinosteroids (BRs) and jasmonic acid (JA) are known to be involved in regulating plant responses to cadmium (Cd) stress. However, their specific roles and interaction in this process remain unclear. In this study, we discovered that exogenous BR alleviated Cd-mediated growth inhibition of rice seedlings. Enhanced Cd tolerance was also observed in m107, a BR-overproduction mutant. Phenotypic analysis of genetic materials involved in BR signaling confirmed the positive role of BR in regulating rice response to Cd toxicity. OsDLT, a key component in the BR signaling pathway, was found to be crucial for BR-mediated Cd tolerance. Further analysis demonstrated that activation of the BR pathway reduced the accumulation of Cd and reactive oxygen species (ROS) by modulating the expression of genes associated with Cd transport and ROS scavenging. Interestingly, transcriptome analysis indicated that the JA pathway was enriched in OsDLT-regulated differently expressed genes (DEGs). Gene expression and hormone assays showed that BR promoted the expression of JA pathway genes and JA levels in plants. Moreover, BR-induced tolerance was compromised in the JA signaling-deficient mutant osmyc2, suggesting that BR-mediated Cd resistance depends on the activation of the JA signaling pathway. Overall, our study revealed the synergistic interaction between BR and JA pathways in rice response to Cd stress, providing insights into the complex hormonal interplay in plant tolerance to heavy metals.