image: LN stress induces RBOHC protein accumulation through an unknown mechanism to produce more ROS. ROS, in turn, promotes the expression of WRKY42 and WRKY58. Particularly, WRKY42 directly transactivates the expression of NRT2.1/NRT2.2/NRT2.4 by binding their promoters, thereby increasing the nitrate uptake and improving plant growth under LN conditions. Whereas WRKY58 regulates the expression of these NRT2 genes in an indirect way
Credit: Created with BioRender.com
Nitrogen is essential for plant growth, but its availability in soil often fluctuates. To cope with nitrate scarcity, plants have evolved sophisticated responses, though many underlying mechanisms remain unclear. In a new study published in Science Bulletin, researchers have delineated a previously unknown signaling cascade that helps plants better absorb nitrate under low nitrogen conditions.
The study focused on the role of reactive oxygen species (ROS) in nitrate starvation responses. Using Arabidopsis thaliana as a model, the team found that the NADPH oxidase RBOHC is responsible for producing ROS under low nitrate stress. Mutants lacking RBOHC showed stunted growth, reduced nitrate uptake, and lower expression of key nitrate transporter genes NRT2.1, NRT2.2, and NRT2.4.
Further investigation revealed that RBOHC-generated ROS activate two transcription factors—WRKY42 and WRKY58—which in turn directly bind to the promoters of NRT2 genes to enhance their expression. Genetic experiments confirmed that plants with suppressed WRKY42/WRKY58 activity mimicked the hypersensitivity of rbohc mutants to low nitrate, while overexpressing these transcription factors improved nitrate uptake and plant growth under nitrogen-deficient conditions.
“Our work uncovers a novel layer of regulation in plant nitrogen nutrition,” said the professor Zheng. “By understanding how plants naturally enhance nitrate uptake under stress, we can explore biotechnological approaches to improve nitrogen use efficiency in agriculture, potentially reducing fertilizer dependency.”
By revealing how RBOHC contributes to nitrate starvation responses, this research provides a conceptual framework for engineering nitrogen-efficient crops by modulating components of the ROS-WRKY-NRT2 signaling module.
Journal
Science Bulletin