Effect of exogenous amino acids on Cu uptake and translocation in maize seedlings

Abstract

This study aimed to assess the effects of four contrasting proteinogenic amino acids on copper (Cu) uptake and translocation in maize (Zea mays L.) seedlings grown in a modified Hoagland solution. Glycine, aspartic acid and lysine at three concentrations (10, 25 and 100 lM) did not have any significant effect on Cu uptake and translocation in maize seedlings over a twoday experimental period. However, cysteine (a reductive amino acid) at the three concentrations increased very significantly (P < 0.01) Cu accumulations in the root symplast and the shoots of maize seedlings in comparison to the control. Cu uptake in the whole plant and Cu translocation from root to shoot were also increased in the cysteine treatments. In the 25 lM cysteine treatment, where cysteine was in moderate excess, the Cu uptake in the whole plant and Cu translocation from root to shoot were significantly (P < 0.01) higher than those of the 10 or 100 lM cysteine treatments, where the concentration of cysteine was equivalent to that of Cu(II) or in great excess according to the stoichiometry of the redox reaction of cysteine with Cu(II). It is hypothesized that the cysteineinduced oxidation state alteration from Cu(II) to Cu(I) could be responsible for the increased Cu uptake and Cu translocation, on the ground that Cu(I), as free cuprous ion or cysteine cuprous complex, may be more available to maize roots than Cu(II).

Interactive effects of cadmium and copper on metal accumulation, oxidative stress, and mineral composition in Brassica napus

“…reductase at plant root surface, which was presumed to increase Cu accumulation in Alyssum inflatum. Likewise, Zhou et al (2007) indicated a close relationship between the extent of Cu uptake by maize seedlings and the potential of cysteine to change the oxidation state of Cu in the rhizosphere. The Cd enhancing effects on copper uptake was also reported in barley (Lachman et al 2004) and Chlorella vulgaris (Franklin et al 2002;Qian et al 2009).…”

“…Previously, Nishizono et al (1987) also observed a higher retention of Cu at root cell wall of Athyrium yokoscense compared to Cd. Zhou et al (2007) also demonstrated that Cu adsorption in maize root cell wall was such tight that a large amount of metal ions were retained in the root apoplast. Despite their varied level of accumulation in B. napus plants, both Cd and Cu mainly accumulated in root (TF \ 100).…”

“…After sampling, roots were desorbed by immersion with 20 mM EDTA-Na 2 for 3 h and then extensively washed in running deionized water for thorough metals elution (Zhou et al 2007;Zeng et al 2012). Then, plant samples (shoots and roots) were oven-dried at 105°C for 3 h, followed by 80°C for 48 h, and weighed immediately after removal from the oven until biomass become stable (Momoh and Zhou 2001).…”

Influence of N, P, and K application on Zea mays L. growth and Cu and Pb accumulation

“…amino acids) in the plant (Jarvis and Whitehead 1981), which could facilitate Cu (II) reduction and translocation. Zhou et al (2007) proved that cysteine can significantly increase Cu uptake and translocation from root to shoot by maize seedlings. Although Pb immobilization due to the presence of P lead to significant reduction in maize Pb uptake, and soil available P concentrations were negatively correlated with shoot Pb concentrations and root Pb uptake (r = -0.752, -0.780, respectively; P < 0.05), TF of Pb did not significantly decrease in the P-fertilized treatments.…”

Amendment of hydroponic nutrient solution with humic acid and glutamic acid in tomato (Lycopersicon esculentumMill.) culture

“…Some studies have suggested that plants have the ability to absorb and utilize AAs as an N source. For example, using three concentrations (10, 25, 100 μM), Zhou et al (2007) showed that cysteine at 25 µM positively affected the growth of maize seedlings while Jämtgård et al (2008) could improve barley (Hordeum vulgare L.) growth with 2, 5, 10 or 25 μM of serine, GA, glycine, arginine and alanine. Zhang et al (2009) demonstrated that AAs, when applied exogenously, significantly increased tomato seedling growth, chlorophyll (Chl) content, micronutrient [iron (Fe), zinc (Zn), copper (Cu) and manganese (Mn)], absorption carotenoid content, and peroxidase (POD) and superoxide dismutase (SOD) activity in leaves more than when earthworm mucus was used.…”