Exogenous Nitric Oxide (NO) Interferes with Lead (Pb)-Induced Toxicity by Detoxifying Reactive Oxygen Species in Hydroponically Grown Wheat (Triticum aestivum) Roots

Abstract

Nitric Oxide (NO) is a bioactive signaling molecule that mediates a variety of biotic and abiotic stresses. The present study investigated the role of NO (as SNP [sodium nitroprusside]) in ameliorating lead (Pb)-toxicity in Triticum aestivum (wheat) roots. Pb (50 and 250 μM) alone and in combination with SNP (100 μM) was given to hydroponically grown wheat roots for a period of 0–8 h. NO supplementation reduced the accumulation of oxidative stress markers (malondialdehyde, conjugated dienes, hydroxyl ions and superoxide anion) and decreased the antioxidant enzyme activity in wheat roots particularly up to 6 h, thereby suggesting its role as an antioxidant. NO ameliorated Pb-induced membrane damage in wheat roots as evidenced by decreased ion-leakage and in situ histochemical localization. Pb-exposure significantly decreased in vivo NO level. The study concludes that exogenous NO partially ameliorates Pb-toxicity, but could not restore the plant growth on prolonged Pb-exposure.

Nitric oxide‐mediated regulation of oxidative stress in plants under metal stress: a review on molecular and biochemical aspects

“…As oxidative stress is a common and severe consequence of various forms of stress, to which Pb exposure is not an exception, the role of NO in alleviating the related damages is an ongoing topic of research (Table ). In this sense, and as demonstrated by the decrease in MDA and ROS levels, concordant throughout various reports (Kopyra and Gwóźdź , Phang et al , Bai et al , Kaur et al , Amooaghaie et al , Jafarnezhad‐Moziraji et al ), this damage mitigation strategy appears promising. Nonetheless, distinct mechanisms underlying this improved tolerance can be found concerning different plants and Pb concentrations.…”

“…A similar result to the latter was observed in Prosopis farcta treated with 400 µM Pb (Pb[CH 3 CO 2 ] 2 ), but over‐time these NO levels tended to decrease (Zafari et al ). Curiously and contrasting with this result, the decrease observed by Kaur et al () was accompanied by an over‐time restoration of the endogenous NO content, once again showing how this response is variable under different conditions.…”

“…Similarly to what happens with other metals, it appears that depending on the experimental conditions and plant species, NO can differently affect the uptake of Pb by plants, either in an increasing (Yu et al ) or decreasing (Amooaghaie et al ) manner, with Phang et al () reporting no effects in this parameter. On the other hand, Pb exposure has also been shown to present different effects on the endogenous pool of NO, as exposure of Sesamum indicum to 2 mM Pb 2+ (Amooaghaie et al ) and Triticum aestivum to 50 and 250 µM Pb 2+ (Pb[NO 3 ] 2 ; Kaur et al ) led to a decrease in NO content, while Pogonatherum crinitum exposed to 100 µM Pb 2+ triggered the accumulation of NO (Phang et al ). A similar result to the latter was observed in Prosopis farcta treated with 400 µM Pb (Pb[CH 3 CO 2 ] 2 ), but over‐time these NO levels tended to decrease (Zafari et al ).…”

The Protective Effect of Baicalin Against Lead-Induced Renal Oxidative Damage in Mice

“…Although the molecular mechanism of renal injury induced by Pb is not well understood, oxidative stress plays an important role in Pb-induced cellular injury, since this metal can influence the processes of lipid peroxidation, which could impact the antioxidant defense system and lead to tissue damage [28][29][30]. SOD, the main endogenous antioxidant enzyme, could protect tissues against the harmfulness of free radicals [31,32].…”

Reduced Glutathione Protects Subcellular Compartments From Pb-Induced ROS Injury in Leaves and Roots of Upland Cotton (Gossypium hirsutum L.)

“…Reactive oxygen species such as H 2 O 2 , OH • and MDA were determined according to Kaur et al (2015) with slight modifications. Briefly, H 2 O 2 was determined based on KI oxidation by H 2 O 2 .…”