# The Maize WRKY Transcription Factor ZmWRKY4 Confers Lead Tolerance by Regulating ZmCAT1 Expression

## TL;DR

A maize gene called ZmWRKY4 helps plants tolerate lead by boosting antioxidant activity through another gene, ZmCAT1.

## Contribution

The study identifies a new regulatory module (ZmWRKY4-ZmCAT1) that enhances lead tolerance in maize through antioxidant mechanisms.

## Key findings

- Overexpression of ZmWRKY4 reduces oxidative damage and increases Pb tolerance in maize.
- ZmWRKY4 directly activates ZmCAT1 by binding to its promoter region.
- ZmWRKY4 overexpression lowers MDA levels and electrolyte leakage under Pb stress.

## Abstract

Lead (Pb) severely impairs plant growth, yet the role of WRKY transcription factors in Pb tolerance in maize remains largely unknown. Here, we identified a Pb-responsive WRKY transcription factor, ZmWRKY4, whose transcript levels were rapidly and strongly induced in maize leaves following Pb exposure. Physiological and biochemical analyses showed that overexpression of ZmWRKY4 substantially enhanced Pb tolerance in maize. Transgenic lines exhibited significantly lower malondialdehyde (MDA) levels and reduced electrolyte leakage than wild-type plants. In addition, ZmWRKY4 overexpression increased catalase (CAT) activity and effectively limited H2O2 accumulation. Further analyses revealed that ZmWRKY4 positively regulates ZmCAT1, a key antioxidant gene involved in H2O2 scavenging, under Pb stress. Electrophoretic mobility shift assays and ChIP-qPCR collectively confirmed that ZmWRKY4 directly binds to W-box elements within the ZmCAT1 promoter in vivo and in vitro, thereby activating its transcription. Together, these findings define a previously uncharacterized ZmWRKY4-ZmCAT1 regulatory module that enhances antioxidant capacity and mitigates oxidative damage during Pb stress. This work provides new insights into the molecular mechanisms underlying heavy metal tolerance in maize and identifies a promising genetic target for developing Pb-resilient crop varieties.