Enhancement of Microsomal Bentazon 6-Hydroxylase and Cinnamic Acid 4-Hydroxylase Activities from Grain Sorghum Shoots

• Published in: Pesticide biochemistry and physiology Vol. 50; no. 1; pp. 92 - 105
• Main Authors: Haack, A.E., Balke, N.E.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.1994
• Subjects: ACIDE CINNAMIQUE; ACIDE NAPHTALENE ACETIQUE; ACIDO CINAMICO; ACIDO NAFTILACETICO; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ADDITIF; ADITIVOS; ALCOHOLES; ALCOOL; CHELATEUR; MEDIO DE CULTIVO; MILIEU DE CULTURE; ORGANITE CELLULAIRE; ORGANULOS CITOPLASMICOS; OXIDORREDUCTASAS; OXYDOREDUCTASE; QUELATOS; SORGHUM BICOLOR; TALLO; TIGE; TRAITEMENT DES SEMENCES; TRATAMIENTO DE SEMILLAS
• ISSN: 0048-3575; 1095-9939
• DOI: 10.1006/pest.1994.1061

Microsomes isolated from excised shoots of grain sorghum ( Sorghum bicolor, (L.) Moench) seedlings arylhydroxylated bentazon herbicide and cinnamic acid to 6-hydroxybentazon and p-coumaric acid, respectively. Constitutive, unprotected bentazon 6-hydroxylase (EC 1.14.13.) activity was low but measurable, whereas, constitutive, unprotected cinnamic acid 4-hydroxylase (EC 1.14.13.11) activity was much greater and was easily measurable. Inclusion of the isolation medium additives (i.e., protectants) ascorbate (40 m M), β-mercaptoethanol (14 m M), and EDTA (10 m M) increased bentazon 6-hydroxylase and cinnamic acid 4-hydroxylase activities to levels 11.6 and 1.7 times the control activities, respectively. Naphthalic anhydride seed treatment induced bentazon 6-hydroxylase activity to a level 1.9 to 8.0 times the control activity, depending on the sorghum variety, but did not significantly induce cinnamic acid 4-hydroxylase activity in any variety. Isolation medium additives and naphthalic anhydride seed treatment independently enhanced bentazon 6-hydroxylase activity resulting in a combined increase in activity 21.3 times the control activity. Differential responses of bentazon 6-hydroxylase and cinnamic acid 4-hydroxylase to isolation medium additives and naphthalic anhydride seed treatment suggest that bentazon and cinnamic acid are hydroxylated by different microsomal monooxygenases in sorghum.