Functional Characterization of Maize ZmMTP1-1 and ZmMTP1-2 Reveals Their Roles in Cd Tolerance

Area of Science:

• Plant Biology
• Genetics
• Environmental Science

Background:

• Cadmium contamination poses significant risks to crop yield and food safety, especially in maize (Zea mays L.).
• Metal tolerance proteins (MTPs) are crucial for metal homeostasis and detoxification, but their specific roles in maize under cadmium stress are not well understood.

Purpose of the Study:

• To investigate the function of maize MTP genes in response to cadmium stress.
• To identify specific MTP members involved in cadmium detoxification and tolerance in maize.

Main Methods:

• Comprehensive expression analysis of the maize MTP gene family under cadmium stress.
• Phylogenetic and structural analyses of identified MTP genes.
• Functional characterization through overexpression in transgenic Arabidopsis thaliana and heterologous expression in yeast.

Main Results:

• Two Zn-CDF members, ZmMTP1-1 and ZmMTP1-2, showed strong transcriptional induction in maize roots under cadmium stress.
• Overexpression of ZmMTP1-1 or ZmMTP1-2 in Arabidopsis enhanced tolerance to cadmium and zinc, improving germination, root growth, survival, and biomass.
• Enhanced tolerance was linked to increased antioxidant enzyme activity, reduced oxidative damage, and coordinated regulation of metal transporter genes.

Conclusions:

• ZmMTP1-1 and ZmMTP1-2 play significant roles in cadmium detoxification and tolerance in maize.
• These genes contribute to heavy metal tolerance through coordinated metal transport and stress response pathways.
• ZmMTP1-1 and ZmMTP1-2 represent valuable genetic resources for developing maize varieties with improved heavy metal tolerance.