Effects of exogenous taurine on growth, photosynthesis, oxidative stress, antioxidant enzymes and nutrient accumulation by Trifolium alexandrinum plants under manganese stress

• Published in: Chemosphere (Oxford) 2022-12, Vol.308, p.136523-136523, Article 136523
• Main Authors: Hafeez, Arslan, Rasheed, Rizwan, Ashraf, Muhammad Arslan, Rizwan, Muhammad, Ali, Shafaqat
• Format: Article
• Language: English
• Subjects: Amino acids; Manganese toxicity; Methylglyoxal; Nutrient acquisition; Osmoprotectants; Oxidative injury; Soluble sugars; Superoxide radical
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.136523

Plants essentially require manganese (Mn) for their normal metabolic functioning. However, excess Mn in the cellular environment is detrimental to plant growth, development, and physio-biochemical functions. Taurine (TAU) is an amino acid with potent antioxidant and anti-inflammatory properties in animals and humans. However, no previous study has investigated the potential of TAU in plant metal stress tolerance. The current study provides some novel insights into the effect of TAU in modulating the defense system of Trifolium alexandrinum plants under Mn toxicity. Manganese toxicity resulted in higher oxidative stress and membrane damage through increased superoxide radical, hydrogen peroxide, malondialdehyde, and methylglyoxal generation alongside enhanced lipoxygenase (LOX) activity. Mn toxicity also resulted in limited uptake of potassium (K+), phosphorus (P), calcium (Ca2+), and increased the accumulation of Mn in both leaf and roots. However, TAU circumvented the Mn-induced oxidative stress by upregulating the activities of antioxidant enzymes (ascorbate peroxidase, peroxidase, catalase, glutathione reductase, glutathione-S-transferase, and superoxide dismutase) and levels of ascorbic acid, proline, anthocyanins, phenolics, flavonoids and glutathione (GSH). Taurine conspicuously improved the growth, photosynthetic pigments, hydrogen sulphide (H2S), and nitric oxide (NO) levels of Mn stressed plants. Taurine also improved the uptake of K+, Ca2+, P and reduced the Mn content in stressed plants. Overall, exogenous taurine might be a suitable strategy to combat Mn stress in T. alexandrinum plants but applications at field levels for various crops and metal toxicities and economic suitability need to be addressed before final recommendations. [Display omitted] •Excess Mn alone decreased Trifolium alexandrinum growth, photosynthesis and biomass.•Exogenous taurine reversed the toxicity in plants caused by excess Mn.•Taurine increased the plant growth and biomass under Mn stress.•Taurine reduced the oxidative stress in Mn-stressed plants by enhancing antioxidant system.•Taurine increased Ca, K, P and decreased Mn concentrations in Mn-stressed plants.