Uptake, translocation and metabolism of the herbicide florasulam in wheat and broadleaf weeds

Abstract

Florasulam is a triazolopyrimidine sulfonanilide post-emergence broadleaf herbicide for use in wheat (Triticum aestivum L.). The selectivity of florasulam to wheat has been determined to be related primarily to a differential rate of metabolism between wheat with a half-life of 2.4 h and broadleaf weeds with half-lives ranging from 19 to >48 h. To a lesser extent, selectivity, at least for the broadleaf weed cleavers (Galium aparine L.), involves uptake differences. Rate of metabolism data were generated using greenhouse-grown plants injected with radiolabelled florasulam and subsequent extraction and processing by high-performance liquid chromatography (HPLC). Structures of metabolites were determined by isolation for nuclear magnetic resonance and liquid chromatography/mass spectrometry. Wheat plants metabolised florasulam by hydroxylation of the aniline ring para to the nitrogen, followed by conjugation to glucose. Metabolism by broadleaf weeds was so slow that isolation of metabolite was not possible, but comparison of HPLC data suggested hydroxylation as the major pathway.

Effect of Environmental Conditions on the Degradation of Florasulam in Typical Soils of Northern China

“…], pineapple weed ( Matricaria spp. ), wild buckwheat ( Polygonum convolvulus L.), and many Cruciferae at very low application rates (Daniau and Prove, 2001; Deboer et al, 2006; Jackson et al, 2000). By the end of 2016, 86 products that contained florasulam were registered in China, and its usage has increased annually (Jabusch and Tjeerdema, 2008; Mukherjee et al, 2016; Zhao et al, 2015; Pesticide Assistant Database [http://www.ny188.cn/Index.html]).…”

The impact of uptake, translocation and metabolism on the differential selectivity between blackgrass and wheat for the herbicide pyroxsulam

“…For root uptake studies, individual plants were transferred from sand into either Erlenmeyer flasks for wheat or 20 mL scintillation vials for blackgrass, each containing an appropriate volume of hydroponic nutrient solution. The composition of the solution has been described previously 4. In the foliar uptake study, plants were grown in the metro mix until harvest.…”

“…When combined with the safener cloquintocet‐mexyl, in commercial formulations pyroxsulam is selective in winter and spring wheat varieties (including durum), winter rye and winter triticale over a wide application window starting early in the fall through to mid‐spring. Previous studies have shown that the degree of herbicidal activity of triazolopyrimidine sulfonanilide herbicides is influenced by the potency of the herbicide on the target enzyme, ALS, and by the rate of herbicide metabolism in the plant 2–4. This study was initiated to understand if uptake, translocation or metabolism had an effect on the efficacy of pyroxsulam in wheat ( Triticum aestivum L.) as compared with blackgrass, a very sensitive species.…”

Chemistry and Fate of Triazolopyrimidine Sulfonamide Herbicides

“…Selectivity of florasulam in wheat has been determined to be primarfl ily related to a differential rate of metabolism between wheat (t 1/2 of 2.4 hr) and broadleaf weeds (t 1/2 ranging from 19 to >48 hr) and, to a lesser extent, to uptake differences (deBoer et al 2006). Differences in cloransulam absorption and translocation partially explained differences in susceptibility among some weed species but not others (Barnes and Oliver 2004).…”

“…fl In plants, TSA herbicides are metabolized via para-hydroxylation of the aniline ring, followed by conjugation with glucose ( Fig. 7; Frear et al 1993;deBoer et al 2006). Microsomal cytochrome P450-dependent monooxygenases were identifi ed as the enzymes responsible for fl fi umetsulam hydroxfl ylation (Frear et al 1993).…”