Physiological Responses and Tolerance of Halophyte Sesuvium portulacastrum L. to Cesium

Abstract

Cesium (Cs) is a soil contaminant and toxic to the ecosystem, especially the plant species. In this study, we have assessed the potential of a halophyte Sesuvium portulacastrum for its Cs tolerance and accumulation. Thirty days old S. portulacastrum plants were subjected to different concentrations of Cs (0, 5, 10, 25, 50, and 150 mg·L−1 Cs) using cesium chloride. The biomass and photosynthetic pigments were not affected up to 25 mg·L−1 Cs treatment while a significant decline in pigment levels was observed at higher concentrations. The Cs treatments increased protein content at low concentrations while higher concentrations were inhibitory. Under Cs exposure, significant induction of antioxidant enzymes such as ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD) was observed. The antioxidant enzyme activities were upregulated up to 50 mg·L−1 Cs but decreased significantly at 150 mg·L−1. The accumulation of Cs was dose and tissue-dependent as evidenced by a higher accumulation of Cs in leaves (536.10 μg·g−1) as compared to stem (413.74 μg·g−1) and roots (284.69 μg·g−1). The results suggest that S. portulacastrum is a hyper-accumulator of Cs and could be useful for the phytoremediation of Cs-contaminated soils.

Effects of Cesium on Physiological Traits of the Catherine’s Moss Atrichum undulatum Hedw.

“…The concentration of H 2 O 2 measured in N. pseudoflabellata under cesium exposure is in range with concentrations tested in this research [ 22 ]. The induction of antioxidant defense (SOD, POX, and CAT) under cesium treatment has also been shown in vascular halophyte Sesuvium portulacastrum L. [ 34 ] and Brassica juncea (L.) Coss [ 35 ]. The SOD activity in roots and shoots of halophyte S. portulacastrum is higher than the values measured in our experiments for long-term exposure, but this one was additionally stressed by salt.…”

“…However, the SOD activity of S. portulacastrum under cesium treatment was not so different compared to the values obtained for short-term exposure. Further, the CAT activity in A. undulatum under conditions of long- and short-term exposure was several times higher than in roots and shoots of S. portulacastrum [ 34 ].…”