High Temperature Disrupts Maize Silk Function Through Metabolic and Oxidative Dysregulation

Area of Science:

• Plant Science
• Molecular Biology
• Agronomy

Background:

• High temperature (HT) stress significantly reduces maize yield by disrupting pollination.
• Mechanisms of HT-induced damage in maize silks, crucial for pollination, are not fully understood.

Purpose of the Study:

• To investigate the molecular and physiological mechanisms underlying heat stress-induced silk growth inhibition (SGI) and silk pollination dysfunction (SPD) in maize.
• To identify key genes, metabolic pathways, and hormonal changes involved in silk thermotolerance.

Main Methods:

• Controlled high temperature (40/30°C) and control (32/22°C) experiments.
• Phenotypic, physiological, metabolic, and transcriptomic analyses of maize silks.
• Gene expression, hormone level, and metabolite profiling.

Main Results:

• HT reduced silk emergence by ~20% and seed set by ~50%, with SPD being the dominant factor in yield loss.
• HT downregulated key genes involved in energy metabolism (sucrose transporters, glycolytic enzymes) and altered hormone levels (increased ABA, IAA; decreased zeatin riboside, brassinolide, JA).
• Oxidative damage due to suppressed flavonoid biosynthesis and impaired reactive oxygen species (ROS) scavenging contributed to SPD, with compromised ROS clearance linked to ZmARF1 and ZmSOD3 expression.

Conclusions:

• HT disrupts maize silk function by altering energy metabolism, hormonal balance, and increasing oxidative stress.
• Key molecular targets for enhancing heat resilience in maize include genes involved in sugar transport, hormone signaling, and ROS detoxification.
• Findings provide insights for breeding heat-resilient maize varieties.