ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Abiotic Stress
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1611383
Exogenous α-lipoic acid mitigates lead (Pb) toxicity in tomato seedlings by regulating metabolites, nutrient uptake, antioxidant defense and redox balance maintenance
Provisionally accepted
Khaled M.A Ramadan1*
Adil Alshoaibi1
Muhammad Naeem Sattar1Khulud S Albalawi2
Fahad Alzuaibr2
Doaa Darwish2Eslam S A Bendary3
Hala Badr Khalil1
Hesham Sayed Ghazzawy1
Mahmoud Adel Ali3Sallah A Al Hashedi1
Mohamed Farag Mohamed Ibrahim3*- 1King Faisal University, Al-Ahsa, Saudi Arabia
- 2University of Tabuk, Tabuk, Tabuk, Saudi Arabia
- 3Ain Shams University, Cairo, Cairo, Egypt
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Water contamination with heavy metals drastically affects plant growth and development. It is more dangerous than other contamination sources due to its cumulative impact over time through plant irrigation. Lead (Pb) is one of the most prevalent and hazardous heavy metals that significantly impede plant growth and development in terrestrial ecosystems. α-lipoic acid (ALA) is a naturally occurring dithiol antioxidant, strong ROS scavenger and metal chelator. Herein, this study was conducted to explore the role of exogenous ALA (0.1 mM) in reducing the Pb-phytotoxicity in tomato seedlings irrigated with Pb contaminated water (250 ppm for 45 days after transplanting). Exposing plants to Pb stress significantly inhibited plant growth, photosynthetic pigments, mineral homeostasis and cell membrane integrity compared to the control plants. In contrast, ALA application markedly revealed a significant improvement in these traits by reinforcing the antioxidant defense systems including superoxide dismutase, guaiacol peroxidase, catalase, glutathione reductase and the major reduced components of ascorbate glutathione cycle. Moreover, ALA significantly enhanced N, P, K, Ca and Fe, reduced Pb uptake and restricted the Pb-induced oxidative damage by reducing the hydrogen peroxide, malondialdehyde and inhibiting the activity of Lipoxygenase. The regression analysis exhibited that ALA demonstrated various significant relationships between the uptake of Pb and the major components of ascorbate glutathione cycle in both leaf and root. In conclusion, our findings deciphered the potential functions of ALA in alleviating Pb-phytotoxicity and enhancing the redox balance of tomato seedlings by enhancing the ratio between the reduced glutathione/ oxidized glutathione and reduced ascorbate/dehydroascorbate.
Keywords: Solanum lycopersicum L, Water contamination, heavy metals, lead toxicity, Ascorbate–glutathione cycle, reactive oxygen species (ROS) and Redox balance
Received: 14 Apr 2025; Accepted: 29 Aug 2025.
Copyright: © 2025 Ramadan, Alshoaibi, Sattar, Albalawi, Alzuaibr, Darwish, Bendary, Badr Khalil, Ghazzawy, Ali, Al Hashedi and Ibrahim. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Khaled M.A Ramadan, King Faisal University, Al-Ahsa, Saudi Arabia
Mohamed Farag Mohamed Ibrahim, Ain Shams University, Cairo, 11566, Cairo, Egypt
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