Taurine regulates ROS metabolism, osmotic adjustment, and nutrient uptake to lessen the effects of alkaline stress on Trifolium alexandrinum L. plants

Alkaline stress is among major environmental constraints that impair plant growth and yield production worldwide. Taurine protects cells from oxidative injury in animals. There exists no report in the literature on taurine functions in plants under environmental constraints. Therefore, the current study was aimed to assess the role of taurine in lessening the harmful effects of alkaline stress on growth of Trifolium alexandrinum L. (Berseem clover). Alkaline conditions (0, 25, 50 and 75 mM Na2CO3) resulted in a notable reduction in growth, chlorophyll contents, relative water content, and essential nutrient uptake. The uptake of toxic Na+ was significantly greater in plants under stress, creating specific ion toxicity. Further, oxidative damage due to alkaline stress was noticeable in plants mirrored as higher hydrogen peroxide (H2O2), superoxide radical (O2•‒), methylglyoxal (MG), malondialdehyde (MDA), and oxidized glutathione GSSG generation. Taurine supplementation (0, 100, and 200 mg L‒1) protected plants from osmotic stress, ions excess toxicity, and oxidative injury under alkaline conditions. Taurine notably reduced the uptake and accumulation of Na+ in plants. In contrast, the K+, Ca2+, and P contents were several folds higher in plants treated with taurine under alkaline conditions.