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article · Frontiers in Plant Science

Impact of foliar application of syringic acid on tomato (Solanum lycopersicum L.) under heavy metal stress-insights into nutrient uptake, redox homeostasis, oxidative stress, and antioxidant defense

2022102 citationsOpen accessKafr el-Sheikh University

In plain language

Lead contamination in soil restricts crop productivity by impeding plant development, reducing nutrient uptake, and triggering oxidative stress. This study assessed the effects of varying lead concentrations on two tomato cultivars, Roma and Cchuas, while evaluating the protective role of foliar syringic acid applications. Elevated lead levels reduced plant biomass, photosynthetic activity, sugar levels, and uptake of essential nutrients such as calcium, magnesium, iron, and phosphorus. Soil lead also elevated oxidative stress markers, antioxidant enzyme responses, and organic acid exudation from roots. Between the two tested varieties, Cchuas displayed superior growth and resilience compared to Roma under heavy metal stress. Foliar application of syringic acid alleviated lead toxicity, leading to improved plant biomass, enhanced gas exchange, and strengthened antioxidant capacity.

Key takeaways

  • Lead accumulation in soil decreased tomato biomass, photosynthetic pigments, and the uptake of essential nutrients.
  • Lead toxicity triggered oxidative stress and altered the exudation of organic acids from plant roots.
  • The Cchuas tomato variety exhibited better growth and stress tolerance than the Roma variety under lead exposure.
  • Foliar application of syringic acid counteracted lead toxicity by boosting plant biomass, gas exchange, and antioxidant defences.

Why it matters

Heavy metal pollution from industrial and economic expansion increasingly threatens agricultural land and reduces food crop yields. Lead accumulation impairs plant health and disrupts essential biological functions. Demonstrating that a simple foliar spray can alleviate heavy metal stress and that certain crop varieties naturally cope better offers practical avenues for sustaining vegetable production in soils compromised by toxic metal contamination.

Commercialisation angle

The findings point to an early-stage opportunity for agrochemical developers formulating plant biostimulants or foliar treatments targeted at crops grown on metal-stressed soils. Potential users include commercial tomato growers and agricultural producers operating on land affected by industrial contamination. Because the abstract reports preliminary trials under specific experimental conditions, extensive field validation, dosage optimisation, and regulatory assessments are necessary before real-world commercialisation is feasible.

AI-generated from the published abstract. Always read the original work before citing.

Abstract

Soil contamination with toxic heavy metals [such as lead (Pb)] is becoming a serious global problem due to the rapid development of the social economy. However, accumulation of Pb in plant parts is very toxic for plant growth and decreases crop yield and productivity. In the present study, we have investigated the different concentrations of Pb in the soil i.e., [0 (no Pb), 50, and 100 mg kg<sup>-1</sup>] to study plant growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress indicators and the response of various antioxidants (enzymatic and non-enzymatic), nutritional status of the plant, organic acid exudation pattern and also Pb accumulation in the roots and shoots of the plants of two varieties of tomato (<i>Solanum lycopersicum</i> L.) i.e., Roma and Cchuas, grown under different levels of synergic acid [no spray (NS), water spray (WS), 0.3-0.5°μM]. Results from the present study showed that the increasing levels of Pb in the soil decreased non-significantly (<i>P</i> < 0.05) shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid content, net photosynthesis, stomatal conductance, transpiration rate, soluble sugar, reducing sugar, non-reducing sugar contents, calcium (Ca<sup>2+</sup>), magnesium (Mg<sup>2+</sup>), iron (Fe<sup>2+</sup>), and phosphorus (P) contents in the roots and shoots of the plants. However, Pb toxicity also induced oxidative stress in the roots and shoots of the plants by increasing malondialdehyde (MDA), hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), and electrolyte leakage (EL) which also induced increased the compounds of various enzymatic and non-enzymatic antioxidants and also organic acids exudation pattern in the roots such as fumaric acid, acetic acid, citric acid, formic acid, malic acid, oxalic acid contents and increased the concentration of Pb in different parts of the plants. Results also show that the Cchuas showed better growth and development compared to Roma, under the same levels of Pb in the soil. The alleviation of Pb toxicity was induced by the application of synergic acid, and results showed that the application of synergic acid increased plant growth and biomass and also increased the gas exchange characteristics and antioxidant capacity in the roots and shoots of the plants. Research findings, therefore, suggested that synergic acid application can ameliorate Pb toxicity in <i>S. lycopersicum</i> varieties and result in improved plant growth and composition under metal stress as depicted by balanced exudation of organic acids.

Research topics

  • Plant Stress Responses and Tolerance
  • Heavy Metals in Plants
  • Heavy metals in environment

Read the original research

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DOI: 10.3389/fpls.2022.950120

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