Silver Uptake, Distribution, and Effect on Calcium, Phosphorus, and Sulfur Uptake

Abstract

Bean, corn, and tomato plants were grown in a nutrient solution labeled with 32P, 4"Ca, or 35S and varying concentrations of AgNO3. Following a 6-hour treatment period, plants were harvested and analyzed. A low Ag' concentration (50 nanomolar) inhibited the shoot uptake of the ions investigated. In the roots, Ca uptake increased whereas P and S uptake decreased.Autoradiograms of bean and corn plants, using "'Ag, showed that Ag+ was uniformly deposited in the bean shoot, but corn 13, 19). Since Ag ions have a high affinity for sulihydryl, amino, and imino groups, it is believed that the uptake of these ions results in their binding to and/or complexing with membrane constituents, and possibly active sites on some enzymes thereby altering membrane permeability (12). Pettersson (15) stated that Ag was not translocated in measurable amounts to the shoots of cucumber plants and that this was the most toxic of the 10 heavy metals he investigated. MATERIALS AND METHODSBean (Phaseolus vulgaris var. Black Valentine), corn (Zea mays hybrid sweetcorn honey and cream), and tomato (Lycopersicon esculentum var. Homestead 24) plants were germinated on wet paper towels for 2, 2, and 5 days, respectively. Young seedlings were then transferred to a nutrient solution and grown in a controlled environmental chamber with a 14-h photoperiod (300 ,uE/M2 s PAR at average leaf height, cool-white fluorescent light), 23 ± 1 C, and RH 50 ± 5%. The basic nutrient solution contained the following salts in Am: Ca(NO3)2, 500; KNO3, 500; MgSO4, 200; KH2PO4, 50; K2HPO4, 25; FeSO4, 13.5; H3BO3, 15; MnCl2, 0.9; ZnCl2, 0.15; MoO3, 0.10; NaCl, 0.15. Individual plants were maintained in 4 liters of aerated nutrient solution (pH 6) and changed every 3 or 4 days.Most treatments were conducted at the following ages: 12 days for bean; 14 days for corn; and 30 days for tomato. Three plants were used for each treatment, with Ag added as nitrate at 0, 0.1, 0.25, and 0.5 j.M (plus 0.05 Am for the S experiment). Unless stated otherwise, the experimental solution volume was 4 liters. Approximately 4 ,uCi/plant of 32P and 10 ,uCi/plant of 45Ca and 3S were used in the tracer studies. Following a 6-h uptake period, plants were harvested, roots rinsed in deionized H20, plants sectioned (roots and shoots systems separated), and dried overnight at 80 C. Individual root and shoot systems were then weighed. For Ca and P studies, plant samples were dry ashed at 600 C, the ash dissolved with dilute HCI and made to 25-ml volume with distilled H20. For the S studies, plant samples were digested with HNO3 and HC104. Five-ml aliquots were then analyzed by liquid scintillation spectrophotometry (Cerenkov method for 32p and a LS cocktail of 10 ml of aqueous counting scintillant for 45Ca and 35S). Uptake rates were determined as mg P (Ca or S) per g dry weight of tissue.Analysis for the "0'°Ag concentration of the nutrient solution and distribution in the translocation and phloem mobility studies was done by solid scintillation spectrometry.Phloem mobility of Ag was ...

Evidence for the involvement of ethene in aerenchyma formation in adventitious roots of rice (Oryza sativa L.)

“…At least two plants were used per treatment. The solutions were changed daily to counteract reductions in nutrients, pH changes and the adsorption of AgNOg (Koontz & Berle, 1980). Solutions used for the stagnant treatments had been previously deoxygenated by gassing with oxygen-free nitrogen for 1 or 2 d. Silver nitrate and nutrients were prepared just before use.…”

Antagonistic effect of silver thiosulphate or 2,5‐norbornadiene on 1‐aminocyclopropane‐1‐carboxylic acid‐stimulated growth of pistils in carnation buds

“…The phytotoxicity of Ag* is well-known (Koontz and Berle 1980), The toxicity of STS appeared to be much less than that of silver nitrate (Den Nijs and Visser 1980), possibly due to the very low Ag* concentration in the STS solution (Gorin et al, 1985), Application of STS, therefore, may lead to a more specific anti-ethylene response (Lis et al, 1984), From Tabs 1 and 2 it seetns that the action of STS is highly specific on ethylene-induced style growth, and does not affect the sucrose-induced growth. This is another example of the negligible phytotoxicity of STS under these experimental conditions, Ethylene production by buds after treatment successively with STS and ACC (Tab.…”

Phytotoxicity, uptake, and accumulation of silver with different particle sizes and chemical forms

“…In an early study on the uptake and transport of Ag ? by plants, Koontz and Berle (1980) noticed much higher Ag in corn leaves than bean leaves. Autoradiographic studies of shoots showed that Ag was evenly distributed in bean leaves, but corn leaf margins and tips were concentrated significantly with higher Ag than other areas.…”