Targeting the Light-Harvesting Complex I Gene Lhca4 Confers Saline-Alkali Tolerance in Rice Without Yield Penalty

Area of Science:

• Plant Biology
• Molecular Biology
• Crop Science

Background:

• Saline-alkali stress is a major threat to global crop production.
• The function of Photosystem I (PSI) light-harvesting complex Lhca4 in stress response is not well understood.

Purpose of the Study:

• To investigate the role of Lhca4 in rice response to saline-alkali stress.
• To elucidate the molecular mechanism by which Lhca4 regulates stress tolerance.

Main Methods:

• Transcriptome analysis to identify differentially expressed genes under stress.
• Genetic analysis using Lhca4 knockout and overexpression rice lines.
• Measurement of reactive oxygen species (ROS) accumulation and antioxidant enzyme activity.
• Analysis of gene expression related to retrograde signaling, photosynthesis, and ROS scavenging.
• Pharmacological treatment with Norflurazon to inhibit retrograde signaling.

Main Results:

• Lhca4 expression is upregulated under saline-alkali stress and acts as a negative regulator of tolerance.
• Lhca4 knockout enhances stress resistance, reduces ROS accumulation, and maintains photosynthetic integrity.
• LHCA4 protein translocates to the nucleus, suppressing retrograde signaling and downstream genes.
• Loss of Lhca4 leads to constitutive activation of retrograde signaling, upregulating protective genes.
• Inhibition of retrograde signaling negates the stress-tolerant phenotype of knockout plants.

Conclusions:

• Lhca4 integrates chloroplast retrograde signals with ROS metabolism to modulate plant adaptation to saline-alkali stress.
• Lhca4 is a key negative regulator of stress tolerance in rice.
• Targeting Lhca4 offers a promising strategy for breeding crops with enhanced resilience to saline-alkali conditions.