Department of Botany, University of Burdwan, Golapbag, Burdwan-713104
Kinetin could induce elongation of wheat coleoptile sections. Though the extent of elongation was less than that of IAA, it required much lower concentration than that of IAA. The growth promoting property of kinetin was negated when the oxidation of endogenous IAA in the coleoptiles was interrupted by pretreatment with chlorogenic acid or ethylenediaminetetra-acetic acid (disodium salt). The growth promoting property of kinetin was also lost when the coleoptiles were treated with sodium salt of diethyl-dithiocarbamie acid or reduced glutathione, which probably formed adducts with endogenous methylene oxindole, an oxidation product of IAA through oxindole pathway of IAA metabolism. The inhibition of growth of coleoptiles pretreated with chlorogenic acid was restored by 67% after addition of ethrel (2-chloroethylphosphonic acid). It is suggested that when the oxindole pathway was blocked, ethrel (ethylene releasing compound) might sufficiently increase, through an alternative pathway involving increased peroxidase activity, the level of endogenous Meox to promote growth. Subsequently, when the peroxidase activity was also inhibited with 2,2’-dipyridyl to block this bypass route, the kinetin induced growth of the coleoptiles was inhibited and could not be restored by ethrel.
