Induction of Glutathione S-Transferase Isozymes in Sorghum by Herbicide Antidotes

Abstract

Certain chemicals referred to as herbicide antidotes protect sorghum from injury by chloroacetanilide herbicides such as metolachlor. The effect of herbicide antidotes on the glutathione S-transferase isozyme complement of etiolated sorghum (Sorghum bicolor [L.] Moench) shoots was examined. Elution profiles of glutathione S-transferase isozymes from untreated and antidote-treated seedlings were generated by fast protein liquid chromatography utilizing an anion exchange (Mono Q) column. In untreated seedlings, there were two glutathione Stransferase isozymes, a major isozyme which exhibited activity toward 1-chloro-2,4-dinitrobenzene and a minor isozyme which exhibited activity toward metolachlor. Treating sorghum seedlings with various antidotes (flurazole, oxabetrinil, CGA-133205, naphthalic anhydride, dichlormid) resulted in the appearance of four to five additional glutathione S-transferase isozymes (depending on the particular antidote) which exhibited activity toward metolachlor as a substrate and little or no activity with 1-chloro-2,4-dinitrobenzene. Treating etiolated sorghum shoots with metolachlor was also found to induce at least four isozymes which exhibited activity toward the herbicide. An increase in glutathione S-transferase activity, measured with metolachlor as substrate, was detected within 4 h after treatment with 30 micromolar oxabetrinil, but 36 hours were required for maximum expression of activity. Addition of either the transcription inhibitor cordycepin or the translation inhibitor cycloheximide inhibited the appearance of glutathione S-transferase activity measured with metolachlor as substrate. The results are consistent with the hypothesis that antidotes confer protection against metolachlor injury in sorghum by inducing the de novo synthesis of glutathione Stransferase isozymes which catalyze the detoxification of the herbicide.Herbicide antidotes are chemical compounds used to protect certain grasses, in particular corn and sorghum, from injury by selected herbicides (4,14). Antidotes that provide varying degrees of protection to sorghum against injury by chloroacetanilide herbicides such as metolachlor or alachlor 'Cooperative investigation of the Minnesota Agricultural Experiment Station and the U.S.

Partial Characterization of Glutathione S-Transferase Isozymes Induced by the Herbicide Safener Benoxacor in Maize

“…Similarly, severa1 herbicide safeners, chemicals that protect crops from herbicide injury, stimulate the conjugation of herbicides with GSH by inducing GST activity in maize (Zea mays L.) and sorghum (Sorghum bicolor [L.] Moench). This increased GST activity appears to be the basis for protection from EPTC (Lay et al, 1975), metolachlor2 (Fuerst and Gronwald, 1986;Gronwald et al, 1987;Dean et al, 1990;Viger et al, 1991b), and alachlor (Mozer et al, 1983). Benoxacor, the herbicide safener for maize studied in this report, stimulated maize GST-M activity and decreased levels of unmetabolized metolachlor in seedlings (Kreuz et al, 1989;Viger et al, 1991b).…”

“…A diversity of xenobiotic chemicals induce GST in mammals, insects, and plants (Boyer, 1989;Clark, 1989;Dean et al, 1990). Similarly, severa1 herbicide safeners, chemicals that protect crops from herbicide injury, stimulate the conjugation of herbicides with GSH by inducing GST activity in maize (Zea mays L.) and sorghum (Sorghum bicolor [L.] Moench).…”

“…The research reported here establishes a foundation for this effort: safener-induced GST isozymes were partially purified and characterized, and preliminary identification of these isozymes was obtained. The specific objectives of this study were (a) to evaluate the effect of benoxacor concentration on maize growth and GST activity; (b) to evaluate the effect of benoxacor on the GST isozyme profile of maize using the FPLC procedure of Dean et al (1990); (c) to partially characterize the isozymes with respect to their activity with CDNB and metolachlor as substrates, and with respect to their reactivity with antisera to GST I and GST I/III (mixture); and (d) to identify GST I, 11, and I11 among the GST activity peaks separated by FPLC.…”

Organ-Specific Expression of Glutathione S-Transferases and the Efficacy of Herbicide Safeners in Arabidopsis

“…Upon treatment of grass crops with safeners, GSTs able to conjugate these herbicides are induced predominantly in shoot tissues. This response is associated with a high level of protection against herbicide damage in maize (Irzyk and Fuerst, 1993;Holt et al, 1995;Dixon et al, 1998), wheat Riechers et al, 1997;Pascal and Scalla, 1999;Xu et al, 2002), rice Hatzios, 2002a, 2002b), and sorghum (Dean et al, 1990;Gronwald and Plaisance, 1998).…”

Pathogen‐Defence Gene prp1–1 from Potato Encodes an Auxin‐Responsive Glutathione S‐Transferase

“…In animal cells, this reaction is utilized in the detoxification of xenobiotics or endogenous reactive products, and also in the binding of steroid hormones (Mannervik and Danielson, 1988 ;Listowsky, 1993). Plant glutathione S-transferases have been intensively studied with regard to their role in the detoxification of herbicides (Shimabukuro et al, 1971;Mozer et al, 1983;Edwards and Owen, 1986;Wiegand et al, 1986;Timmerman, 1989;Dean et al, 1990;Hunaiti and Bassam, 1990). However, little is known about the biological function and regulation of plant glutathione Stransferases.…”