PROMOTION OF ADVENTITIOUS ROOT FORMATION BY HELIANGINE AND ITS REMOVAL BY CYSTEINE1

Abstract

Heliangine at 10⁻⁴M promoted the adventitious root formation in hypocotyls of cuttings taken from light-grown (1,900 lux) seedlings of Phaseolus mungo. The promotion was almost completely reduced by simultaneously supplied 3×10⁻⁴M cysteine or 1.5×10⁻⁴M cystine, but not suppressed by 3×10⁻⁴M of reduced glutathione, alanine or serine. A 4 hr pretreatment with 3×10⁻⁴M cysteine made Phaseolus cuttings less sensitive to heliangine, but cysteine supplied after the treatment with heliangine brought about no effect on the action of heliangine. Cysteine also removed the inhibiting effect of heliangine on the indoleacetic acid-induced elongation of etiolated Avena coleoptile sections. In an aqueous solution heliangine formed an addition product with cysteine, indicating that cysteine can inactivate heliangine without any biological processes. On Phaseolus adventitious rooting, no effect was observed of p-chloromercuribenzoic acid, N-ethylmaleimide, 1,4-naphthoquinone, coumarin or penicillin. Reactivity toward sulfhydryl groups alone does not qualify a substance to be a promotor of root formation. Maleic hydrazide at 10⁻⁴M promoted root formation, but its effect was not removed by cysteine.