The transcription factor bZIP68 negatively regulates cold tolerance in maize

Area of Science:

• Plant Molecular Biology
• Crop Genetics
• Evolutionary Biology

Background:

• Maize (Zea mays) is vulnerable to cold stress due to its tropical origins, impacting global food security.
• Limited understanding exists regarding the molecular mechanisms underlying cold tolerance in maize.
• Identifying key regulators of cold response is crucial for developing climate-resilient crops.

Purpose of the Study:

• To identify novel regulators of cold tolerance in maize.
• To investigate the role of transcription factors in mediating cold stress responses.
• To explore the evolutionary history of cold tolerance mechanisms in maize domestication.

Main Methods:

• Transcriptome analysis to identify differentially expressed genes under cold stress.
• Molecular characterization of the bZIP68 transcription factor, including its regulation and function.
• Analysis of genetic variation and selection at the bZIP68 locus during maize domestication.

Main Results:

• bZIP68, a basic leucine zipper (bZIP) transcription factor, was identified as a negative regulator of cold tolerance in maize.
• bZIP68 was found to repress the expression of cold-induced DREB1 transcription factor genes.
• Phosphorylation of bZIP68 at Ser250 regulates its stability and activity under cold stress.
• A specific promoter polymorphism (Indel-972) in bZIP68 influences its expression difference between maize and teosinte.

Conclusions:

• bZIP68 acts as a key repressor of cold-induced gene expression in maize.
• The regulation of bZIP68 stability and activity by phosphorylation is critical for cold response.
• Evolutionary selection on the bZIP68 promoter during domestication provides a potential target for enhancing maize cold tolerance.