Physiological and Cellular Ultrastructural Responses of Sesuvium portulacastrum under Cd Stress Grown Hydroponically

Abstract

This study aimed to investigate the physiological and cellular mechanisms of Sesuvium portulacastrum under heavy metal stress to evaluate possible tolerance and adaptation mechanisms in a metal-polluted environment. The physiological and cellular ultrastructural responses of S. portulacastrum were studied hydroponically under exposure to a range of cadmium (Cd) concentrations (50 µM to 600 µM) for 28 days. The activity of antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), changes in chlorophyll, and cellular ultrastructural content were examined. There was no significant difference in chlorophyll content in the leaf under the stress of 300 μM, but 400 μM and 600 μM Cd stress showed significantly decreased chlorophyll content. The SOD activity indicates an increase under the Cd stress of 100 μM for leaves, 300 μM for stems, and 50 μM for roots; after that, the SOD activity gradually decreased with increasing Cd concentrations. But POD activity was considerably increased with increasing Cd stress. CAT activity showed a gradual increase in concentrations until 300 μM of Cd stress and then decreased sharply in roots, stems, and leaf tissues. Cd stress had a considerable impact on the structure of the roots, stems, and leaves cells, such as distorted and thinner cell walls and the deformation of chloroplasts, mitochondria, and other organelles. Therefore, the increased number of nucleolus in the cell nucleus suggests that cells may be able to maintain their protein synthesis in a stressful environment. This study concludes that SOD is the dominant antioxidant enzyme activity during low Cd toxicity (<100 μM), while POD is the dominant enzyme activity during higher Cd toxicity (>100 μM).

Adesmia pinifolia, a Native High-Andean Species, as a Potential Candidate for Phytoremediation of Cd and Hg

“…In the present study, Cd accumulation was distinctly higher in roots compared to shoots, but the accumulation did not linearly increase with Cd concentration. Similar results were reported by Jawad Hassan et al [47] in two sorghum cultivars (Sorghum bicolor) and other species, such as Sesuvium portulacastrum [48] and Satureja hortensis [49]. These results indicate that A. pinifolia has a strong ability to accumulate Cd in root tissue.…”

Alterations in the Anatomy and Ultrastructure of Leaf Blade in Norway Maple (Acer platanoides L.) Growing on Mining Sludge: Prospects of Using This Tree Species for Phytoremediation

“…Hence, the space in the cells was limited and we suppose that it could explain the limited increase in vacuole size. Alterations in chloroplast ultrastructure, similar to those described in Norway maple growing on mining sludge, have also been observed in other plant species, e.g., Salix viminalis [16], Hordeum vulgare [37], and Sesuvium portulacastrum [34], which were all exposed to Cd; in Inga subnuda treated with Cu [85]; in Polygonum perfoliatum, an Mn-tolerant species, when exposed to extremely high concentrations of Mn [86] when growing on mine tailings; in Vicia faba [60]; and in the non-metallicolous ecotype of S. vulgaris exposed to Ni [24]. It is worth noting, however, that, e.g., metallicolous ecotypes of S. vulgaris treated with Ni did not show such alterations in their chloroplasts [24].…”

The Uptake, Transfer, and Detoxification of Cadmium in Plants and Its Exogenous Effects

“…The toxic effects of Cd are manifested in physiological and ecological aspects, but the degree of its toxic effects is related to Cd concentration and treatment time, plant species, and cultivars [ 206 ]. For instance, a low Cd concentration of 100 nM affected the growth of sunflower [ 207 ], while Sesuvium portulacastrum showed significant cellular damage only after 300 μM CdCl 2 treatment [ 208 ]. Furthermore, certain plants are classified as Cd hyperaccumulators for their ability to accumulate Cd in their aerial tissues in excess of 100 mg Kg −1 , showing high tolerance and uptake capacity [ 209 , 210 ].…”