PlantView Support Plant Drought Stress Research: A rice calmodulin-like protein OsCML27 participates in drought tolerance by fine-tuning OsRbohB-mediated ROS signaling

New progress has been made in understanding the molecular regulation mechanism of rice drought tolerance.

Researchers Jingjing Wen and Kunming Chen from Northwest A&F University have made a breakthrough in the field of molecular regulation of drought stress responses in rice. Their findings, entitled “A rice calmodulin-like protein OsCML27 participates in drought tolerance by fine-tuning OsRbohB-mediated ROS signaling,” were published in “Science Advances” (IF = 14.95, a comprehensive top journal).

This study provides new insights into the negative regulation mechanism of ROS signaling in drought-stressed rice and reveals the OsMRLK63–OsCML27–OsRbohB regulatory module, offering key theoretical foundations and genetic resources for developing drought-resistant rice varieties.

Drought is a major abiotic stress that limits rice yield and threatens global food security. Under drought conditions, the rice NADPH oxidase OsRbohB produces large amounts of reactive oxygen species (ROS). Moderate ROS accumulation activates drought defense signaling, while excessive ROS production causes oxidative damage. Although kinase pathways that positively regulate OsRbohB activation have been extensively studied, the mechanisms by which plants precisely suppress excessive ROS production and maintain the balance between calcium signaling and ROS signaling remain unclear. This study systematically characterized the biological function of the calcium sensor protein OsCML27 and identified the OsMRLK63–OsCML27–OsRbohB regulatory module, revealing a novel molecular “brake” mechanism that fine-tunes ROS signaling under drought stress.

Through integrated multi-omics approaches, including gene editing, protein interaction analysis, in vivo fluorescence imaging, and physiological phenotype characterization, the researchers elucidated the complete regulatory pathway. Drought stress induces the interaction between the receptor-like kinase OsMRLK63 and OsCML27, specifically phosphorylating the Ser11 site of OsCML27. This phosphorylation modification significantly enhances OsCML27 protein stability. The accumulated OsCML27 then binds to the N-terminal functional domain of OsRbohB in a Ca²⁺-dependent manner, directly suppressing OsRbohB-mediated ROS production and preventing drought-induced oxidative damage. Genetic analyses showed that OsCML27-overexpressing plants exhibited faster water loss and reduced drought survival, whereas oscml27 knockout mutants displayed improved water retention and stronger drought tolerance compared with wild-type plants. Complementation lines restored wild-type drought-responsive phenotypes. Moreover, the conserved Ser11 site of OsCML27 is widely present in OsCML24/32 homologs in rice and related crop species, indicating that this regulatory mechanism is evolutionarily conserved. This pathway forms a negative feedback loop: drought activates OsMRLK63 to promote ROS production, ROS induces intracellular Ca²⁺ influx, and Ca²⁺ further enhances OsCML27-mediated inhibition of OsRbohB, thereby precisely balancing oxidative signaling intensity during drought stress.

Experiments using PlantView

In this study, the research team used the PlantView plant in vivo imaging system from Guangzhou Biolight Biotechnology to perform luciferase complementation imaging (LCI) assays, validating the in vivo protein interactions between OsMRLK63 and OsRbohA, OsRbohB, and OsCML27, respectively.