EFFECTS OF CLOMAZONE ON IPP ISOMERASE AND PRENYL TRANSFERASE ACTIVITIES IN CELL-SUSPENSION CULTURES AND COTYLEDONS OF SOLANACEOUS SPECIES

Laboratory assays were conducted to determine the sensitivity of tomat o and tobacco cell suspension cultures and tomato and pepper cotyledon s to clomazone. A comparison of fresh weight and carotenoid content in dicated up to a three-fold difference between the clomazone-tolerant t obacco and clomazone-susceptible tomato cell suspension cultures. In c ontrast, an approximate 60-fold difference between the tolerant pepper and susceptible tomato cotyledons was observed when total chlorophyll and carotenoid contents were measured. The effect of clomazone and it s possible metabolites on in vivo and in vitro extractable IPP isomera se (EC 5.3.3.2) and prenyl transferase (EC 2.5.1.29) activity was inve stigated. There was no clear inhibitory effect of clomazone or possibl e clomazone metabolites upon enzyme activity in tomato or tobacco cell suspension cultures or on light or dark grown tomato or pepper cotyle dons. No specific enzymatic target site of clomazone was identified in correlation with the reduction in total chlorophyll or carotenoid con tent. Nomenclature: Clomazone, lorophenyl)methyl]-4,4-dimethyl-3-isoxa zolidinone; pepper, Capsicum annum L. cv Yolo Wonder L; tobacco, Nicot iana tabacum L. 'KY-14'; tomato, Lycopersicon esculentum Mill. 'Niagar a.'