A new study published in BMC Plant Biology demonstrates that applying rice husk biochar to soil dramatically enhances drought tolerance in Brassica napus by activating the salicylic acid (SA)-mediated glutathione (GSH) synthesis pathway. The researchers observed that drought alone caused severe oxidative damage, marked by increased ROS (H₂O₂ and O₂⁻), lipid peroxidation, reduced chlorophyll, suppressed shoot biomass, and significant disruption of GSH redox homeostasis.
Biochar application reversed many of these stress effects. Plants grown under drought with biochar showed better soil water retention, higher relative water content, and improved chlorophyll levels. At the biochemical level, biochar increased reduced glutathione nearly 3-fold, improved the GSH/GSSG ratio 4.5-fold, and enhanced glutathione reductase activity. Biochar also upregulated GSH1 while suppressing GPX7, reducing excessive glutathione oxidation.
A key discovery was the hormonal shift: drought triggered an ABA-dominant response, but biochar lowered ABA levels by 28% while increasing salicylic acid by 1.5-fold. Expression of SA biosynthesis (ICS1) and signaling (NPR1) genes rose sharply with biochar, linking SA enhancement directly to redox recovery. PCA and correlation analyses supported this SA-GSH regulatory mechanism.
Overall, the study concludes that biochar mitigates drought-induced oxidative stress through an integrated mechanism involving improved water relations, activation of SA signaling, and restoration of the GSH-based antioxidant system. The authors highlight that this is the first detailed characterization of SA-mediated GSH redox control triggered by biochar in B. napus, offering promising implications for agricultural resilience under water stress conditions.
Reference
Lee, BR., Park, SH., Muchlas, M. et al. Biochar application alleviates drought-induced oxidative stress by activating the salicylic acid-mediated glutathione synthesis pathway in Brassica napus. BMC Plant Biol 25, 1582 (2025). https://doi.org/10.1186/s12870-025-07575-7
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