Leaf transcriptomic response mediated by cold stress in two maize inbred lines with contrasting tolerance levels

Area of Science:

• Plant Biology
• Molecular Biology
• Genetics

Background:

• Maize (Zea mays L.) is a thermophilic crop sensitive to cold temperatures, which can delay maturity.
• Cold stress induces significant physiological and molecular changes in plants, including alterations in cell membranes, photosynthesis, and energy metabolism.

Purpose of the Study:

• To investigate the molecular mechanisms of cold tolerance in maize seedlings.
• To compare the physiological and transcriptomic responses of cold-tolerant and cold-sensitive maize inbred lines under cold stress.

Main Methods:

• Leaf transcriptome sequencing was performed on two maize inbred lines (B144 and Q319) exposed to 5°C for 0, 12, and 24 hours.
• Leaf microstructure and relative electrical conductivity were measured to assess physiological responses.
• Differentially expressed genes were analyzed for enrichment in specific biological pathways.

Main Results:

• Cold stress significantly impacted gene expression in both maize lines, with enrichment in pathways related to photosynthesis, MAPK signaling, hormone transduction, circadian rhythm, secondary metabolites, ribosome, and proteasome.
• The cold-tolerant line B144 upregulated D1 proteins to protect photosystem II from photooxidation.
• The cold-sensitive line Q319 showed an inability to close its stomata under cold stress.

Conclusions:

• Maize seedlings utilize common stress-responsive pathways but differ in specific tolerance mechanisms.
• Cold tolerance in maize is associated with effective photosystem protection and regulated stomatal response.
• Key regulators of cold stress tolerance include modifications in photosystem II, stomatal dynamics, secondary metabolism, and circadian rhythm, alongside MAPK and phytohormone signaling.