Figure 1. DAB, NBT, and Evan's blue staining revealed lower ROS accumulation and reduced cell death in OsPXG9-overexpressing rice seedlings compared with wild-type under drought and salt stress. (Tran AD, et al., 2025)
Accumulation of ROS and cell death level in rice seedlings from WT and ox lines under drought and salt stress.
Rice Peroxygenase-9 Negatively Regulates Production of Reactive Oxygen Species and Increases Cellular Resistance to Abiotic Stress
Paper
2025
International Journal of Molecular Sciences |
DOI
Background
This study investigates rice peroxygenase-9 (OsPXG9), a class I caleosin/peroxygenase involved in oxylipin metabolism and abiotic stress tolerance. OsPXG9 preferentially catabolizes 9-LOX-derived hydroxy fatty acids and uses hydroperoxides as oxygen donors, producing epoxy and trihydroxy derivatives. Overexpression in rice reduced ROS accumulation and drought- and salt-induced apoptotic cell death. Transgenic lines also modulated antioxidant enzyme expression, showing lower basal antioxidant transcripts but stress-induced activation. The results indicate OsPXG9 helps maintain redox balance and enhances rice resilience to drought and salt stress.
Key Findings
OsPXG9 acts on 9-LOX pathway products, preferring 9(S)-HODE/HOTE over 13-LOX substrates; it uses HOOH or CuOOH to epoxidize hydroxy fatty acids, yielding epoxy and trihydroxy derivatives. Overexpression lines ox2-1 and ox2-2 showed reduced DAB/NBT staining and Evans blue cell death under drought and salt stress, with lower MDA. They survived salt stress better than wild type. In unstressed plants, antioxidant genes OsAPX1, OsCAT-A, OsSOD1, and OsGR were downregulated in strong overexpressors, suggesting OsPXG9 lowers basal ROS and compensatory antioxidant demand. Under stress, antioxidant gene expression recovered or increased, particularly OsSOD1, supporting ROS detoxification. Thus OsPXG9 negatively regulates ROS accumulation, limits lipid peroxidation and apoptotic cell death, and enhances drought/salt resistance, likely by detoxifying lipid hydroperoxides and contributing to redox homeostasis.
Contribution
Creative Biogene provided the pCAMBIA1201 vector (Cat. #VET1345) used to construct the OsPXG9 overexpression plasmid. This commercial vector enabled Agrobacterium-mediated rice transformation and generation of transgenic lines for functional analysis. It supported the overexpression experiments central to assessing OsPXG9's role in abiotic stress tolerance.
This study investigates rice peroxygenase-9 (OsPXG9), a class I caleosin/peroxygenase involved in oxylipin metabolism and abiotic stress tolerance. OsPXG9 preferentially catabolizes 9-LOX-derived hydroxy fatty acids and uses hydroperoxides as oxygen donors, producing epoxy and trihydroxy derivatives. Overexpression in rice reduced ROS accumulation and drought- and salt-induced apoptotic cell death. Transgenic lines also modulated antioxidant enzyme expression, showing lower basal antioxidant transcripts but stress-induced activation. The results indicate OsPXG9 helps maintain redox balance and enhances rice resilience to drought and salt stress.
Key Findings
OsPXG9 acts on 9-LOX pathway products, preferring 9(S)-HODE/HOTE over 13-LOX substrates; it uses HOOH or CuOOH to epoxidize hydroxy fatty acids, yielding epoxy and trihydroxy derivatives. Overexpression lines ox2-1 and ox2-2 showed reduced DAB/NBT staining and Evans blue cell death under drought and salt stress, with lower MDA. They survived salt stress better than wild type. In unstressed plants, antioxidant genes OsAPX1, OsCAT-A, OsSOD1, and OsGR were downregulated in strong overexpressors, suggesting OsPXG9 lowers basal ROS and compensatory antioxidant demand. Under stress, antioxidant gene expression recovered or increased, particularly OsSOD1, supporting ROS detoxification. Thus OsPXG9 negatively regulates ROS accumulation, limits lipid peroxidation and apoptotic cell death, and enhances drought/salt resistance, likely by detoxifying lipid hydroperoxides and contributing to redox homeostasis.
Contribution
Creative Biogene provided the pCAMBIA1201 vector (Cat. #VET1345) used to construct the OsPXG9 overexpression plasmid. This commercial vector enabled Agrobacterium-mediated rice transformation and generation of transgenic lines for functional analysis. It supported the overexpression experiments central to assessing OsPXG9's role in abiotic stress tolerance.