Plant epicuticular lipids: alteration by herbicidal carbamates.

The effect of several carbamates and trichloroacetic acid on the biosynthesis of epicuticular lipids from leaves of pea (Pisum sativum) was tested by chemical and visual methods. The carbamates tested included S-(2,3-dichloroallyl) diisopropylthiocarbamate (diallate), N-(3-chlorophenyl) isopropylcarbamate (chloropropham), S-ethyl dipropylthiocarbamate, and 2-chloroallyl diethyldithiocarbamate. Diallate reduced epicuticular lipids by 50% when the plants were root-treated and by 80% when vapor-treated. These results were supported by scanning electron microscopy and carbon replica techniques with transmission electron microscopy. The ratio of wax lipid components in the diallate-treated plants remained unchanged, with the exception of the primary alcohols, which were reduced. Diallate appears to interfere with the biosynthesis of a precursor to the elongation-decarboxylation pathway of lipid synthesis. N-(3-Chlorophenyl)isopropylcarbamate had no significant effect on total amounts of extractable epicuticular lipids, nor did it alter the structure of the wax formation on the leaves. The scanning electron microscopy micrographs indicated that S-ethyl dipropylthiocarbamate significantly reduced wax formation on pea leaves. 2-Chloroallyl diethyldithiocarbamate altered the structure of the wax formations, but not the total amount of wax (scanning electron microscopy). Trichloroacetic acid had little effect on wax deposition compared to diallate or S-ethyl dipropylthiocarbamate (scanning electron microscopy). The implication of the effect of the carbamates on epicuticular lipids and penetration of subsequent topically applied chemicals is discussed.

Metabolic fate of 3,4-dichloropropionanilide in plants: the metabolism of the propionic Acid moiety.

3,4-Dichloropropionanilide-(14)C (propanil) labeled in either the C-1 or C-3 carbon atoms of the propionic acid moiety was applied to the roots of pea (Pisum sativum L.) and rice (Oryza sativa L.) plants in nutrient solution (0.1 mm-0.28 mm). Radioactivity was detected throughout the treated plants, but the greatest labeling was found in the roots. None of the products that contained aniline were radioactive, suggesting that the plants split the propionic acid moiety from propanil. The fate of the propionate moiety of propanil was determined by recovery of (14)CO(2) from plants exposed to propanil-(14)C. The time-course of the (14)CO(2) production demonstrated that the intact propionic acid was cleaved from the propanil and subsequently catabolized by the beta-oxidation catabolic sequence. The appearance of radioactivity in the shoots was attributed to the incorporation of products of propionate metabolism. Both the susceptible pea plants and the tolerant rice plants converted a high percentage of the administered propanil-(14)C to (14)CO(2).

Metabolism of 3,4-dichloropropionanilide in plants: the metabolic fate of the 3,4-dichloroaniline moiety.

Studies to elucidate the fate of 3,4-dichloropropionanilide (propanil) in rice (Oryza sativa L. var. Nato) plants have shown that the propanil molecule is cleaved and the propionic acid moiety metabolized. To ascertain the fate of the 3,4-dichloroaniline moiety of propanil, rice plants were exposed to propanil in liquid culture. The roots and shoots of treated rice plants were extracted and quantitatively assayed for four aniline-containing metabolites. One of the four metabolites proved to be 3,4-dichloroaniline, while the remaining three metabolites contained complexed 3,4-dichloroaniline. N-(3,4-dichlorophenyl)-glucosylamine was identified as one of the complexes. A time-course study of the four metabolites indicated the appearance of the 3,4-dichloroaniline-containing metabolites within 6 hours. After 14 days of treatment, the complexed aniline metabolites amounted to only 10 percent of the total propanil administered to the rice plants.