Contamination of vegetables with heavy metals and microplastics is a major environmental and human health concern. This study investigated the role of taurine (TAE) in alleviating arsenic (As) and polyvinyl chloride microplastic (MP) toxicity in broccoli plants. The experiment followed a completely randomized design with four replicates per treatment. Plants were grown in soil spiked with MP (200 mg kg-1), As (42.8 mg kg-1), and their combination (As + MP) with or without taurine (TAE; 100 mg L-1) foliar supplementation. Results demonstrated that MP, As, and As + MP toxicity markedly decreased growth, chlorophyll content, photosynthesis, and nutrient uptake in broccoli plants. Exposure to individual or combined MP and As increased oxidative damage, indicated by elevated methylglyoxal (MG), superoxide radical (O2 & sdot;-), hydrogen peroxide (H2O2), hydroxyl radical (& sdot;OH), and malondialdehyde (MDA) levels alongside intensified lipoxygenase (LOX) activity and leaf relative membrane permeability (RMP). Histochemical analyses revealed higher lipid peroxidation, membrane damage as well as increased H2O2 and O2 center dot- levels in the leaves of stressed plants. Micropalstic and As toxicity deteriorated anatomical structures, with diminished leaf and root epidermal thickness, cortex thickness, and vascular bundle area. However, TAE improved the antioxidant enzyme activities, endogenous ascorbate-glutathione pools, hydrogen sulfide and nitric oxide levels that reduced H2O2, O2 & sdot;-, & sdot;OH, RMP, MDA, and activity of LOX. Taurine elevated osmolyte accumulation that protected membrane integrity, resulting in increased leaf relative water content and plant biomass. Plants supplemented with TAE demonstrated improved anatomical structures, resulting in diminished As uptake and its associated phytotoxicity. These findings highlight that TAE improved redox balance, osmoregulation, ion homeostasis, and anatomical structures, augmenting tolerance to As and MP toxicity in broccoli.

Exploring the saline-adapted species and the mechanisms by which they have evolved in saline conditions would be a feasible way to utilize saline soils. Based on this approach, this study aimed to evaluate the seed germination and seedling responses of the five abundant Asteraceae species to salinity stress and determine the antioxidant and non-antioxidant defense strategies by which these species demonstrated variations in salinity tolerance. Milk thistle (Silybum marianum), blessed thistle (Cnicus benedictus), pot marigold (Calendula officinalis), safflower (Carthamus tinctorius), and cardoon (Cynara cardunculus) were subjected to 0 (control), 50, 100, 150, 200 and 250 Mm NaCl concentrations. Calendula officinalis (CO) showed the highest, Silybum marianum (SM) and Cnicus benedictus (CB) moderate, and Carthamus tinctorius (CT) followed by Cynara cardunculus (CC) the least inhibition of seed germination and seedling growth at all given salinity levels. Each species utilized different antioxidant mechanisms in response to salinity. Peroxidase (POX) was the major antioxidative enzyme in resistance species, CT and CC, while catalase and superoxide dismutase were more pronounced in moderate, SM and CB, and susceptible, CO, species, respectively. Besides, all species accumulate a considerable amount of proline in response to salinity, which was more evident in the 150 and 200 Mm NaCl concentrations. From the results, it can be concluded that CT and CC had superior saline-tolerance capacity compared to other species due to their longer seedling roots, higher POX activity, and proline accumulation associated with reduced cellular damage.