ZmMYB104 Enhances Heat-Stress Tolerance by Activating ZmCAT2 Expression in Maize

Area of Science:

• Plant molecular biology
• Plant physiology
• Genetics

Background:

• Temperature fluctuations critically impact plant growth and development.
• Understanding heat-stress tolerance mechanisms in crops like maize (Zea mays L.) is crucial for food security.
• Molecular underpinnings of thermotolerance in maize require further elucidation.

Purpose of the Study:

• To investigate the role of the MYB transcription factor ZmMYB104 in maize thermotolerance.
• To identify downstream target genes regulated by ZmMYB104 under heat stress.
• To characterize the ZmMYB104-mediated regulatory pathway for heat-stress response.

Main Methods:

• Molecular cloning and expression analysis of ZmMYB104.
• Subcellular localization and transactivation assays.
• RNA sequencing and DNA affinity purification sequencing (DAP-seq) to identify target genes.
• Electrophoretic mobility shift assays (EMSA) and dual-luciferase reporter assays to confirm ZmMYB104-ZmCAT2 interaction and transcriptional activity.

Main Results:

• ZmMYB104 expression is induced by heat in maize seedlings and functions as a transcriptional activator in the nucleus.
• Overexpression of ZmMYB104 enhances maize seedling resistance to heat stress.
• ZmCAT2 was identified as a direct downstream target of ZmMYB104.
• The ZmMYB104-ZmCAT2 regulatory module enhances hydrogen peroxide (H₂O₂) scavenging capacity, reducing reactive oxygen species (ROS) accumulation and oxidative damage under heat stress.

Conclusions:

• ZmMYB104 confers thermotolerance by directly activating the transcription of ZmCAT2, a key enzyme in ROS detoxification.
• The ZmMYB104-ZmCAT2 regulatory module is a novel component of plant heat-stress responses in cereal crops.
• This regulatory axis offers a potential genetic target for developing climate-resilient maize varieties through molecular breeding.