Response to Antimony Toxicity in Dittrichia viscosa Plants: ROS, NO, H2S, and the Antioxidant System

Abstract

Dittrichia viscosa plants were grown hydroponically with different concentrations of Sb. There was preferential accumulation of Sb in roots. Fe and Cu decreased, while Mn decreased in roots but not in leaves. Chlorophyll content declined, but the carotenoid content increased, and photosynthetic efficiency was unaltered. O2●− generation increased slightly, while lipid peroxidation increased only in roots. H2O2, NO, ONOO−, S-nitrosothiols, and H2S showed significant increases, and the enzymatic antioxidant system was altered. In roots, superoxide dismutase (SOD) and monodehydroascorbate reductase (MDAR) activities declined, dehydroscorbate reductase (DHAR) rose, and ascorbate peroxidase (APX), peroxidase (POX), and glutathione reductase (GR) were unaffected. In leaves, SOD and POX increased, MDAR decreased, and APX was unaltered, while GR increased. S-nitrosoglutathione reductase (GSNOR) and l-cysteine desulfhydrilase (l-DES) increased in activity, while glutathione S-transferase (GST) decreased in leaves but was enhanced in roots. Components of the AsA/GSH cycle decreased. The great capacity of Dittrichia roots to accumulate Sb is the reason for the differing behaviour observed in the enzymatic antioxidant systems of the two organs. Sb appears to act by binding to thiol groups, which can alter free GSH content and SOD and GST activities. The coniferyl alcohol peroxidase activity increased, possibly to lignify the roots’ cell walls. Sb altered the ROS balance, especially with respect to H2O2. This led to an increase in NO and H2S acting on the antioxidant system to limit that Sb-induced redox imbalance. The interaction NO, H2S and H2O2 appears key to the response to stress induced by Sb. The interaction between ROS, NO, and H2S appears to be involved in the response to Sb.

Effect of Thallium(I) on Growth, Nutrient Absorption, Photosynthetic Pigments, and Antioxidant Response of Dittrichia Plants

“…In Arundo donax and Coix lacryma-jobi , Pu et al [ 48 , 86 ] find 50 µg L −1 Tl to cause a decrease in the chlorophyll content, while lower concentrations have no effect. The increase in the carotenoid content and the carotenoid/chlorophyll ratio that has been observed in Dittrichia could be due to the role of carotenoids as ROS scavengers, thus protecting PSII functionality from oxidative damage [ 11 , 98 , 99 , 100 , 101 ]. The chlorophyll a/chlorophyll b ratio indicates the degree of appression of the thylakoid membranes in the chloroplast, being inversely proportional to the degree of appression, which, in turn, causes the “light harvesting complexes II” (LHCII) to be more closely connected, increasing the light-gathering capacity, and, therefore, the efficiency of energy transmission.…”

“…The ascorbate–glutathione (AsA–GSH) cycle removes hydrogen peroxide (H 2 O 2 ), maintaining redox homeostasis [ 2 ]. The production of nitric oxide (NO), the main RNS, is also related to plants’ response to stress [ 9 , 10 , 11 ]. It acts at the level of the expression of the defense genes that are involved in eliminating ROS [ 12 , 13 , 14 ] and plays a key role in the defense mechanisms against different stressors [ 15 ], including heavy metals, such as Cd and As [ 9 , 16 , 17 , 18 , 19 ].…”

“…Dittrichia can colonize poor soils and also those that are degraded due to anthropic activities, such as mining, with high concentrations of heavy metals and metalloids [ 58 ]. Dittrichia are capable of absorbing and accumulating large amounts of Cd, Cu, Fe, Ni, Pb, Zn, As, and Sb [ 11 , 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. The participation of the components of the AsA–GSH cycle, as well as NO and H 2 S, in the Sb accumulation process has recently been reported [ 11 , 63 ].…”

“…Dittrichia are capable of absorbing and accumulating large amounts of Cd, Cu, Fe, Ni, Pb, Zn, As, and Sb [ 11 , 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. The participation of the components of the AsA–GSH cycle, as well as NO and H 2 S, in the Sb accumulation process has recently been reported [ 11 , 63 ]. However, this capacity varies depending on the different genotypes or populations, which shows great genetic plasticity [ 60 , 61 , 62 ].…”

Silicon Actuates Poplar Calli Tolerance after Longer Exposure to Antimony

“…Antimony might negatively influence the uptake of essential nutrients and disturb the synthesis of some metabolites [ 15 ]. It has also been reported that Sb can increase the peroxidation of membrane lipids [ 1 ] and cause severe oxidative stress [ 16 , 17 ]. Wang et al [ 18 ] found that the highest Sb accumulation was in the roots of Oryza sativa L. The presence of Sb was also confirmed in the straws and grains of the plants.…”