Rice is a major food crop in the world, and it is sensitive to salt stress. The salty environment will cause a significant decrease in rice yield. The circadian clock is an intrinsic time maintenance mechanism that plays a key role in regulating the response of plants to abiotic stresses. However, it is still unclear whether the core components of the rice circadian clock are involved in the regulation of salt tolerance and related mechanisms.
Researcher Wang Lei’s group from the Institute of Botany, Chinese Academy of Sciences discovered that at the transcriptional level, rice produces OsPRR (Oryza sativa Pseudo-Response Regulator) gene family Only the OsPRR73 gene of the 5 members can specifically respond to salt stress signals. In mutants with loss of function of osprr73 caused by T-DNA insertion or gene editing, the expression phase and expression amplitude of multiple rice circadian clock-related genes were affected, indicating that OsPRR73 is the core component of the rice circadian clock. In a high-salt environment, the loss-of-function mutants of osprr73 all exhibit a high accumulation of sodium ions and reactive oxygen species (ROS), resulting in a phenotype of reduced salt tolerance. Through further phenotypic analysis, the researchers found that the osprr73 mutant is sensitive to Na2SO4 but not sensitive to MgCl2 and mannitol, indicating that sodium ion toxicity is the main reason for the decreased salt tolerance of the osprr73 mutant. Transcriptomics analysis combined with biochemical evidence identified an OsHKT2;1 gene encoding a sodium ion absorption transporter, which is the direct target gene of OsPRR73. The OsPRR73 protein binds to the promoter of the OsHKT2;1 gene, inhibits the expression of OsHKT2;1 in the time dimension, reduces the absorption of sodium ions in a specific time window, and avoids excessive accumulation of sodium ions. Co-immunoprecipitation of OsPRR73 protein combined with mass spectrometry identification technology and protein interaction experiments revealed that OsPRR73 can interact with histone deacetylase HDAC10 (Histone deacetylase 10), thereby inhibiting the transcription of OsHKT2;1 gene. Further studies have shown that in terms of salt stress tolerance, OsHKT2;1 is genetically located downstream of OsPRR73, and regulates the salt tolerance of rice by regulating sodium ion homeostasis and ROS levels. This research is the first to systematically analyze the molecular mechanism of rice circadian clock components regulating salt stress, and will provide theoretical support and related genetic resources for the development and cultivation of salt-tolerant rice varieties. At present, the application of related genes in regulating rice salt tolerance has applied for national patents.
related research results were published in The EMBO Journal. Wang Lei’s research group is currently the first author of the paper by Wei Hua, a PhD student in the research group, and Wang Lei is the corresponding author of the paper. The research work is supported by the key R&D program projects of the Ministry of Science and Technology, the general projects of the National Natural Science Foundation of China, and the Strategic Leading Science and Technology Special Project (Type B) of the Chinese Academy of Sciences.
Working model of rice circadian clock core components regulating salt tolerance