In vitro Conversion of Neutral Gibberellin-like Substances from Potato Tubers

Abstract

RECENTLY, a chemically neutral substance, separated chromatographically from a methanol extract of potato tubers, was reported to stimulate elongation of ‘Morse's Progress’ dwarf pea plants grown under red light^1,2. This bioassay is particularly sensitive to certain gibberellins, and the neutral substance, tentatively termed potato factor I, was therefore considered gibberellin-like. The substance was separated under well-controlled conditions to avoid the possibility of contamination by acid substances. Its discovery was of considerable interest since gibberellin-like substances that exhibit activity on the dwarf pea bioassay were previously found only in the acid fraction of plant extracts. The growth promotion by potato factor I became of even greater interest when, after two weeks standing and rechromatography, its activity had disappeared from its original place on the chromatogram and a new zone, now giving an acid test and showing much higher biological activity, appeared at R_F 0.5–0.6.