Metabolism of Strobilurins by Wheat Cell Suspension Cultures

Abstract

Strobilurin fungicides are a leading class of antifungal chemicals used today in agricultural applications. Although degradation of some strobilurin fungicides has been assessed in plant residues, little information has appeared in the literature concerning the rates of metabolism of these fungicides in plants. In this study, we explored plant metabolism of three strobilurin fungicides, azoxystrobin, kresoxim-methyl, and trifloxystrobin, using wheat cell suspension cultures. Trifloxystrobin and kresoxim-methyl were completely metabolized within 24 h, whereas the metabolism of azoxystrobin was relatively slow with half-lives up to 48 h depending on specific experimental conditions. Metabolic rates of these fungicides were affected by the amounts of compound and cells added to the media. Structural analysis of metabolites of trifloxystrobin and kresoxim-methyl by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance spectroscopy (NMR) indicated that trifloxystrobin was first demethylated followed by subsequent hydroxylation, whereas kresoxim-methyl was largely demethylated. In contrast, a number of minor metabolites of azoxystrobin were present suggesting a differential metabolism of strobilurins by wheat cells.

Uptake, Translocation, and Subcellular Distribution of Azoxystrobin in Wheat Plant (Triticum aestivum L.)

“…Myung et al observed that 14 C-azoxystrobin could be demethylated in wheat cell culture, but the demethylated metabolite was difficult to accumulate because it could be rapidly degraded into water-soluble unknowns. 32 The balance between uptake and metabolism may be the reason for the equilibrium of the wheat−water system, as observed for pyrene, lindane, and trifluralin. 25,33 Thus, maintenance of the concentration of azoxystrobin in wheat plants depended on the sustained uptake of the fungicide from the nutrient solution.…”

“…The continuous absorption of azoxystrobin by wheat roots did not lead to a synchronous increase in the concentration of all parts of the wheat plant, which revealed that a fraction of the absorbed azoxystrobin was metabolized in the wheat body. Myung et al observed that 14 C-azoxystrobin could be demethylated in wheat cell culture, but the demethylated metabolite was difficult to accumulate because it could be rapidly degraded into water-soluble unknowns . The balance between uptake and metabolism may be the reason for the equilibrium of the wheat–water system, as observed for pyrene, lindane, and trifluralin. , Thus, maintenance of the concentration of azoxystrobin in wheat plants depended on the sustained uptake of the fungicide from the nutrient solution.…”

Biological characterization of fenpicoxamid, a new fungicide with utility in cereals and other crops

“…Cell suspension cultures of wheat ( Triticum aestivum L. cv. Anza) were prepared and grown as previously described . Aliquots (7 mL) of 7‐day‐old cell suspensions (cell density equivalent to 30 mg cells mL −1 ) or culture medium alone (Murashige and Skoog medium containing 2 mg L −1 2,4‐D ) were dispensed into six‐well culture plates and incubated on an orbital shaker at 130 rpm and 27 °C for 24 h before addition of 14 C‐labeled fenpicoxamid.…”

Metabolism of pharmaceutical and personal care products by carrot cell cultures

“…Advanced techniques such as time-of-flight (TOF) MS, high resolution MS, and nuclear magnetic resonance spectroscopy (NMR) may be needed for further identification and verification of potential metabolites, as reported by Macherius et al (2012) and Myung et al (2013).…”

“…xenobiotics, such as 4-nonylphenol (Bokern et al, 1996), bisphenol A (Schmidt and Schuphan, 2002), polycyclic aromatic hydrocarbons (Huckelhoven et al, 1997;Kolb and Harms, 2000), and fungicides (Myung et al, 2013). So far only 3 PPCPs have been studied for their plant metabolism using plant cell cultures.…”