Assimilation of exogenous cyanide cross talk in Oryza sativa L. to the key nodes in nitrogen metabolism
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Assimilation of exogenous cyanide cross talk in Oryza sativa L. to the key nodes in nitrogen metabolism Cheng-Zhi Li1 Li Yang1 Yu-Juan Lin1 Hua Zhang1 Saeed Rad1 Xiao-Zhang Yu ●
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Accepted: 4 August 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Exogenous cyanide (CN−) effects on nitrogen (N) uptake, transport, and assimilation in rice seedlings were investigated at the biochemical and molecular levels. Seedlings were treated with either a 2-d or 4-d supply of potassium cyanide (KCN) in the nutrient solution containing nitrate (NO3−) or ammonium (NH4+). Although a KCN-induced increase was recorded in the activity of β-cyanoalanine synthase (β-CAS) in rice tissues of both NH4+-fed and NO3−-fed seedlings, the former showed a significantly greater assimilation rate for CN− than the latter. The addition of KCN decreased NO3− uptake and assimilation, whereas a negligible impact was observed in NH4+ treatments. Enzymatic assays showed a marked activities enhancement of glutamine synthetase (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH) in NH4 + -fed seedlings after KCN exposure. Similarly, the rises occurring in nitrate reductase (NR) and GDH activity in NO3−-fed seedlings were also detected after 2-d exposure to KCN, whereas a significant reduction of GS and GOGAT activities was determined. The results suggest that although exogenous KCN at moderate or high concentrations caused repressively effects on biomass growth of both NH4+-fed and NO3−-fed rice seedlings, the nontoxic concentration of KCN supplied can serve as a supplemental N source in plant nutrition and N metabolism. Keywords Cyanide β-cyanoalanine synthase Nitrogen metabolism Oryza sativa L. ●
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Introduction As a required macronutrient for plants, nitrogen (N) is involved in multiple metabolic processes. N nutrition is essential for plant growth, development, and productivity (Giorgi et al. 2009). Much of researches have demonstrated that plants are capable to absorb a variety of N species, which are converted to amino acids, nucleic acids, proteins, chlorophylls, and such metabolites through various enzymatic reactions (Xiong et al. 2006). Plant N metabolism includes uptake, assimilation, and remobilization (Ameziane et al. 2000). NH4+ and NO3− are the two main N
Supplementary information The online version of this article (https:// doi.org/10.1007/s10646-020-02265-6) contains supplementary material, which is available to authorized users. * Xiao-Zhang Yu [email protected] 1
College of Environmental Science & Engineering, Guilin University of Technology, Guilin 541004, People’s Republic of China
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sources taken up by plants. It has been reported that specific transporters are responsible for the acquisition of both N species across the plasma membrane of root cells (Fan et al. 2017). Besides, the fate and assimilation of NO3− and NH4+ within plant tissues differ significantly (Lu et al. 2014). Numerous lines of evidence suggest that a significant reducti
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