Behavior of¹⁴C-Haloxyfop-Methyl in Intact Plants and Cell Cultures

Abstract

Behavior of14C-haloxyfop-methyl {methyl 2-[4-[(3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoate} was examined in intact plants of soybean [Glycine max(L.) Merr. ‘Mead’], shattercane [Sorghum bicolor(L.) Moench. ♯ SORVU], and yellow foxtail [Setaria glauca(L.) Beauv. ♯ SETLU] and in cell cultures of soybean and yellow foxtail. Foliar absorption of14C-haloxyfo-methyl by intact plants was almost complete within 48 h. Significant translocation occurred within 48 h of treatment, with soybean and shattercane plants translocating more14C than yellow foxtail. Metabolism of14C-haloxyfop-methyl in intact plants was similar among species. Haloxyfop-methyl was rapidly hydrolyzed to haloxyfop in treated leaves and then translocated to metabolically active areas within the plants. Significant quantities of polar products were also isolated. Soybean cells in suspension culture contained higher levels of14C than did yellow foxtail cells. Most of the14C in soybean cells was haloxyfop-methyl, while yellow foxtail contained mostly haloxyfop.

Detoxification of chlorotoluron in a chlorotoluron‐resistant biotype of Alopecurus myosuroides. Comparison between cell cultures and whole plants

“…These systetn s have some advantages over whole plants when studying herbicide tnetabolistn, such as (1) their relative hotnogeneity when they ate used at an appropriate gtowth phase (Sterling and Baike 1988), (2) a reduced content of pigtnents that can facilitate analytical measurements as they mask results (Matringe et al 1990), (3) the avoidance of absorption and translocation barriers in species in which they complicate metabolism studies (Lamoureux et al, 1991) and (4) their insensitivity to photosynthesis-inhibiting herbicides (as they are nonchlorophyllous cultures), allowing herbicide metabolistn to be evaluated in the absence of phytotoxicity (Grosstnann et al 1992). Nevertheless, although no major qualitative differences have been found in pesticide metabolism between intact plants and cell cultures of the same species, quantitatively significant differences have been observed (Buhler et al 1985).…”

Comparing Techniques for Quantifying Haloxyfop Absorption and Translocation in Johnsongrass (Sorghum halepense)

“…Radiolabeled samples of haloxyfop have been applied in 0.2-|il (7), 0.5-|il (8), 2.0-|il (16), and unspecified size (3) droplets and as an even smear on the leaf surface (10). Leaf wash solutions used to remove nonabsorbed haloxyfop include distilled water plus an adjuvant (9), methanol (10), ethanol (13), acetone (13), acetonitrile (8), distilled water plus an adjuvant followed by methanol and then chloroform (7), and distilled water followed by chloroform (3). The size of the treated area as well as total volume of the treatment solution has ranged from 2.0 |il applied on a 2.0-cm 2 area (7) to 90 unapplied to two or three leaves (8).…”

“…Typically, more than 90% of recovered 14 C was ab sorbed following foliar applications of ,4 C-haloxyfop (3,9,14,16). Absorption, however, has ranged from more than 98% after 48 h in green foxtail [Setaria viridus (L.) Beauv.]…”

“…(9), and more than 97% after 96 h in quackgrass [Elytrigia repens (L.) Nevski] (16) to approximately 50% in grain sorghum [Sorghum bicolor (L.) Moench] after 48 h (13). Generally less than 5% of recovered ,4 C occurred in the leaf wash (3,9,16). However, as much as 20% of recovered 14 C occurred in leaf washes from bermudagrass [Cynodon dactylon (L.) Pers.]…”

Comparative Effects of Quizalofop and Its Esters on Acetyl-CoA Carboxylase and Fatty Acid Biosynthesis in Corn Leaf Chloroplasts

“…Several reports suggest that biologically active forms are the corresponding free acids which are formed in treated leaf tissues presumably by carboxylesterase and translocated to meristematic regions in the phloem. [10][11][12] Most evidence for this assumption is based on absorption translocation and metabolism studies on f oliar-applied 14C-labeled herbicides. However a radioactive material translocated from a treated leaf blade to other parts of the plant accounted for less than 1% of the applied 14C -label but we made no attempt to characterize the translocated radioactive material this time.…”