MAPK-dependent copper tolerance mechanisms revealed by integrated physiology and transcriptomics in peanut

Area of Science:

• Plant Biology
• Molecular Biology
• Environmental Science

Background:

• Copper is an essential micronutrient but can be toxic at elevated levels.
• Understanding plant responses to heavy metal stress is crucial for agriculture and environmental management.

Purpose of the Study:

• To investigate the physiological and molecular mechanisms of copper stress response in peanut (Arachis hypogaea L. c.v. 'Haihua No. 1').
• To identify key genes and pathways involved in copper tolerance.

Main Methods:

• Peanut seedlings were treated with 50 mg/L CuSO₄.
• Measurements included root morphology, ion content, oxidative stress indices, and antioxidant enzyme activities.
• RNA sequencing (RNA-seq) and quantitative PCR (qPCR) were used to analyze gene expression.

Main Results:

• Copper stress induced the expression of MPK4, which phosphorylated NAC and LBD proteins.
• NAC regulated copper defense genes, while LBD influenced lateral root growth and detoxification genes (GST, POD).
• These molecular events enhanced peanut's detoxification and antioxidant capacity.

Conclusions:

• The MPK4 pathway, along with NAC and LBD transcription factors, plays a critical role in peanut's copper stress response.
• These genes represent potential targets for breeding copper-tolerant peanut cultivars.