Interactive effects of Salicylic acid and nitric oxide in alleviating zinc toxicity of Safflower (Carthamus tinctorius L.)

Abstract

The purpose of this study was to assess the possible protective role of exogenous salicylic acid (SA), sodium nitroprusside (SNP), a donor of nitric oxide, and their combination on 21-day-old safflower (Carthamus tinctorius L.) seedlings grown under zinc (Zn) stress. The results revealed that exposure to 500 µM ZnSO.7HO for 10 days markedly reduced the root and shoot dry weights in Zn-treated plants, while the application of SA, SNP and specially SA + SNP significantly increased the root and shoot dry weights in seedlings subjected to Zn stress. Addition of SA, SNP and SA + SNP interestingly reduced root-to-shoot translocation of zinc and increased significantly the level of glutathione (GSH) and ascorbate (ASC) in leaves of Zn-stressed plants. The Zn-treated plants supplemented with SA and SNP revealed an improved activity of ascorbate-glutathione cycle enzymes and those enzymes which are involved in glyoxalase system as compared to the plants treated with Zn only. However, no significant relationship was found between SA or SNP supplementation and glutathione S-transferase activity in Zn-stressed plants. These findings demonstrate that exogenous application of SA or SNP could ameliorate the negative effects of Zn on safflower plants probably by stimulation of antioxidant defense and glyoxalase systems.

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

“…In fact, the levels of O 2 ·− estimated through nitroblue tetrazolium (NBT) staining in Zn‐exposed Triticum aestivum plants were reduced upon treatment with NO (Buet et al ). Concerning the antioxidant battery, NO was found to improve the AsA‐GSH cycle in plants under Zn stress of different species, either by regulating AsA and GSH contents and/or their related antioxidant enzymes, such as APX and GR (Chen et al , Namdjoyan et al , Nasiri‐Savadkoohi et al , Tripathi et al ). On an opposite way, NO was found to inhibit CAT and APX activities, while enhancing SOD activity (Xu et al ).…”

“…Although a microarray‐based work revealed that SNP upregulated transcripts coding for zinc finger proteins at 1000 µM, the exposure to 100 µM SNP did not follow the same tendency (Parani et al ). Accordingly, the exogenous application of 100 µM SNP to Carthamus tinctorius plants exposed to 500 mg kg −1 Zn lowered Zn accumulation, especially in shoots (Namdjoyan et al ). Similarly, plants treated with a NO donor and grown in the presence of 2 µM Zn exhibited lower Zn concentrations in roots and shoots, than those only exposed to Zn (Buet et al ).…”

Role of nitric oxide in plant responses to heavy metal stress: exogenous application versus endogenous production

“…Combined effect of adding SNP and GSH inhibiting the uptake and translocation of Cu. (Mostofa et al, 2015) Cu_3 (Namdjoyan et al, 2017)…”

Modulation of growth and oxidative stress by seed priming with salicylic acid in Zea mays L. under lead stress

“…Salicylic acid (SA), a phenolic compound, is an endogenous growth regulator and signal molecule whose role is well established in the defense mechanism under stress conditions. Previous studies show that exogenously applied SA effectively alleviated heavy metal stresses like copper (Cu), mercury (Hg), arsenic (As), cadmium (Cd), zinc (Zn) and Pb toxicity (Zhou et al 2009;Wang et al 2011;Mostofa and Fujita 2013;Singh et al 2015;Roychoudhury et al 2016;Namdjoyan et al 2017). The exogenous SA could protect Vallisneria natans plants against Pb toxicity by preventing Pb-induced oxidative stress (Wang et al 2011).…”