Melatonin Mediates Lead Accumulation Reduction via the RsWRKY26-RsHIPP26-RsASMT2 Module in Radish Taproot.
Xiaoli Zhang1, Mingjia Tang1, Wenjing Chu1
1National Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Key Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of MOAR, College of Horticulture, Nanjing Agricultural University, Zhongshan Biological Breeding Laboratory, Nanjing 211800, PR China.
Journal of Hazardous Materials
|December 5, 2025
Summary
Melatonin (MT) reduces lead (Pb) in radish by activating the RsWRKY26-RsHIPP26-RsASMT2 pathway. This discovery offers a strategy for safer radishes and improved Pb uptake in breeding programs.
Area of Science:
- Plant molecular biology
- Environmental toxicology
- Agricultural science
Background:
- Soil lead (Pb) contamination poses a significant threat to vegetable crop safety and quality.
- Melatonin (MT) is known to reduce Pb accumulation in plants, but the underlying molecular mechanisms in radish are not fully understood.
Purpose of the Study:
- To elucidate the molecular mechanism of melatonin-mediated reduction of lead accumulation in radish.
- To identify key genes and regulatory pathways involved in lead detoxification in radish.
Main Methods:
- RNA sequencing (RNA-seq) to identify differentially expressed long non-coding RNAs (lncRNAs) and protein-coding (PC) genes under lead and melatonin treatments.
- Gene expression analysis, including overexpression studies in radish, Arabidopsis, and yeast.
- Yeast one-hybrid (Y1H) and DNA ligation assay (DLA) to confirm direct promoter binding and transcriptional activation.
Main Results:
- A total of 11,265 lncRNAs and 4730 lncRNA-PC gene pairs were identified; many were enriched in oxidoreductase activity.
- Melatonin treatment upregulated RsASMT2, which, upon overexpression, enhanced reactive oxygen species scavenging and reduced Pb accumulation.
- The RsWRKY26 transcription factor directly activated RsHIPP26 and RsASMT2 promoters, and its overexpression led to decreased Pb accumulation in radish roots.
Conclusions:
- The melatonin-mediated RsWRKY26-RsHIPP26-RsASMT2 module plays a crucial role in coordinating the reduction of lead accumulation in radish.
- This study establishes an effective strategy for producing radishes with low lead accumulation, contributing to food safety.
- The findings facilitate genetic improvement of lead-uptake traits in radish breeding programs.
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