Effects of antimony on redox activities and antioxidant defence systems in sunflower (Helianthus annuus L.) plants

Abstract

The alterations induced by the toxicity of antimony (Sb) in the roots and leaves of sunflower plants were determined. The plants were grown hydroponically with different concentrations of Sb, a heavy metal which reduces biomass production and growth. There was preferential accumulation of Sb in the tissues of the roots, with the concentrations in the leaves being much lower. The accumulation of other mineral elements was also altered, especially that of Fe and Zn. Chlorophyll content declined, as also did the photosynthetic efficiency, but the carotenoid content remained unaltered. The total content of phenolics, flavonoids, and phenylpropanoid glycosides rose, evidence of their participation in the defence response. Increases were observed in the amount of superoxide anion in both roots and leaves, and in lipid peroxidation levels, especially with the highest Sb concentration of 1.0 mM. The induced oxidative stress leads to a strong increase in the SOD, POX and APX antioxidant activities, while the GR activity was only increased in the leaves and at the 1.0 mM Sb concentration. In contrast, the DHAR activity increased considerably in both organs. The GSNOR activity increased only in roots, and the total RSNOs increased. The total amount of AsA + DHA increased in roots and remained unaltered in leaves, whereas that of GSH + GSSG decreased considerably in all cases. As a whole, these results are evidence for the development of a strong oxidative stress induced by Sb, with there being a clear imbalance in the content of the compounds that constitute the AsA/GSH cycle. 0.5 mM Sb enhances GST expression, especially in leaves. This, together with the increase that was observed in the amount of GSH, may play an important part in detoxification. This oxidative stress affects both the phenolic and the ROS/RNS metabolic processes, which seems to implicate their involvement in the plant's defence and response to the stress.

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“…This indicates that the production of thiols, including cysteine and glutathione, is triggered by the occurrence of contaminants in the shoots. The correlations, in the data excluding G4 where the cysteine synthesis seemed disturbed, suggest that glutathione is the main thiol compound involved in the stress alleviation of As, Pb and Sb, which is in agreement with previous studies (Li et al, 2009;Pourrut et al, 2011;Ortega et al, 2017).…”

Effects of Antimony Stress on Photosynthesis and Growth of Acorus calamus

“…The root Sb concentration of the arsenic hyperaccumulator Pteris vittata reached 12000 mg/kg and accounted for 99% of hosted Sb in the plants (Tisarum et al, 2014). The enrichment ability of sunflower ( Helianthus annuus L. ) under Sb stress was larger in roots than in leaves, but Sb stress inhibited plant growth; the Sb accumulation in the aboveground part significantly altered the physical conditions of sunflower, reduced intercellular gaps and made leaf tissues closer (Vaculík et al, 2015; Ortega et al, 2017). According to the report, root is the main organ for taking up metal nanoparticles from water are badly influenced in comparison with shoot in some plants (Tripathi et al, 2016; Anshu et al, 2017).…”

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

“…The plants were then treated with the basal nutrient solution supplemented with KSb(OH) 6 to final concentrations of 0.00 (control), 0.50 mM, and 1.00 mM Sb. Each cultivation solution was adjusted to pH 5.8, continuously aerated, and changed every 4 days [ 17 , 38 ]. The plants were exposed to the Sb for 17 days.…”

“…Heavy metal and metalloid toxicity induces a strong increase in the production of ROS, RNS, and RSS, which leads to alteration of the cellular redox balance [ 4 , 15 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Under stress conditions, the increase in ROS production leads to an alteration of the cellular redox balance [ 27 ].…”