Domestication-selected COG4-OsbZIP23 module regulates chilling tolerance in rice

Area of Science:

• Plant genetics
• Molecular biology
• Crop science

Background:

• Identifying natural variations is crucial for crop breeding, particularly for traits like chilling tolerance.
• While several quantitative trait loci (QTLs) for chilling tolerance (qCTS) have been identified, the underlying dual regulatory modules remain underexplored.

Purpose of the Study:

• To identify and characterize the major genes and regulatory mechanisms underlying chilling tolerance in rice.
• To investigate the roles of Chilling-tolerance in Geng/japonica rice 4 (COG4) and OsbZIP23 in conferring cold tolerance.

Main Methods:

• Haplotype analysis and geographical distribution studies of COG4 variations.
• Investigating the binding of cold-induced OsbZIP23 to the COG4 promoter.
• Analyzing the differential expression of COG4 in response to cold stress.

Main Results:

• A major gene, COG4 (encoding ENAC1), was identified as a key regulator of chilling tolerance.
• The japonica-specific haplotype COG4^jap, associated with Var9(CT), exhibits enhanced promoter activity.
• Cold-induced OsbZIP23 preferentially binds to the COG4^jap promoter, leading to higher COG4 expression and improved chilling tolerance.
• Both COG4^jap and OsbZIP23^jap show evidence of artificial selection during japonica rice domestication.

Conclusions:

• The OsbZIP23^jap-COG4^jap module is a critical regulatory mechanism for chilling tolerance in japonica rice.
• This study reveals valuable genetic variations for developing climate-resilient rice varieties through molecular breeding.