Knockout of the OsNAC113 Transcription Factor Causes High Salt Resistance in Rice

Area of Science:

• Plant Molecular Biology
• Plant Physiology
• Genetics and Genomics

Background:

• The NAC transcription factor family is crucial for plant stress responses.
• Understanding specific NAC factors like OsNAC113 in rice (Oryza sativa L. spp. japonica) is vital for improving crop resilience.
• OsNAC113's role in tissue-specific characteristics and stress response mechanisms requires detailed investigation.

Purpose of the Study:

• To analyze the tissue-specific expression and stress response regulatory mechanisms of the rice transcription factor OsNAC113.
• To elucidate the function of OsNAC113 in salt stress tolerance using CRISPR-Cas9 genome editing.
• To identify the molecular pathways regulated by OsNAC113 under high-salt stress.

Main Methods:

• Quantitative Real-Time PCR (qRT-PCR) for gene expression analysis under various stress conditions.
• CRISPR-Cas9 genome editing to create OsNAC113 knockout rice mutants.
• Physiological and biochemical assays (relative water content, chlorophyll, soluble sugar, malondialdehyde, enzyme activities) to assess salt tolerance.
• RNA-sequencing (RNA-seq) and KEGG/GO pathway analysis to identify differentially regulated genes and pathways.
• Comparative metabolomic analysis to determine metabolic pathway alterations.

Main Results:

• OsNAC113 expression significantly changes under drought, high salt, temperature stress, and hormone treatments (ABA, GA3).
• OsNAC113 knockout mutants exhibited significantly enhanced salt tolerance, with improved growth, survival rates, relative water, chlorophyll, and soluble sugar content compared to wild-type rice.
• Mutants showed reduced malondialdehyde content and increased antioxidant enzyme activities (superoxide dismutase, peroxidase, catalase) under salt stress.
• RNA-seq and pathway analysis revealed that OsNAC113 knockout affects plant hormone signaling, MAPK signaling, and metabolic pathways including amino acid, carbohydrate, and lipid transport and metabolism.
• Metabolomic analysis indicated changes in flavonoid biosynthesis and ABC transporters in OsNAC113 knockout mutants.

Conclusions:

• OsNAC113 plays a significant role in regulating rice response to salt stress.
• Functional loss of OsNAC113 enhances salt tolerance through improved physiological status and antioxidant defense.
• OsNAC113 regulates salt stress response by modulating plant hormone and MAPK signaling pathways, as well as key metabolic processes.
• The study provides a foundation for molecular breeding of rice with improved salt tolerance by targeting OsNAC113.