M. Jain et N. Bhalla-sarin, Effect of glyphosate on the activity of DAHP synthase isozymes in callus cultures of groundnut (Arachis hypogaea L.) selected in vitro, I J BIOCH B, 37(4), 2000, pp. 235-240
Two isozymes of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHP
synthase or DS, EC 4.1.2.15) from the callus cultures of Arachis hypogaea L
. were resolved by DEAE cellulose column chromatography and characterized u
sing selective assays based on divalent cation requirements and regulation
by the end-product amino acids. The total extractable activity of DAHP synt
hase did not show any change in the glyphosate sensitive and tolerant cell
lines when compared to 5-enolpyruvylshikimate-3-phosphate synthase (EPSP sy
nthase, EC 2.5.1.19), the known target of inhibition by glyphosate. However
, the activities of both, DAHP synthase and EPSP synthase were inhibited by
glyphosate in vitro. The inhibitory effects of glyphosate on the activitie
s of (a) EPSP synthase and DAHP synthase, and (b) isozymes of DAHP synthase
, have been compared. The data indicate that the Co2+ dependent isozyme of
DAHP synthase is a putative target for the action of glyphosate in A. hypog
aea.