Acid & neutral gibberellin-like substances in potato tubers

Abstract

Gibberellin-like substances were found in extracts of potato peelings and buds made with various organic solvents at low (2.5) and neutral (7.3) pH. Several active zones were at Rf''s heretofore not shown to exhibit gibberellin activity. The neutral compounds were provisionally designated potato factors I and II. A solution of isopropyl alcohol, ammonium hydroxide, and water (10:1:1 v/v) was used as developing solvent. Dwarf peas grown under red light and dwarf maize d-1, d-3, and d-5 were used for bioassay. A neutral fraction contained a zone at Rf 0.3-0.4 that was active on peas but not on d-1 or d-5. Gibberellin-like substances at Rf 0.5-0.7 in a chloroform extract were active on dwarf pea, and d-3 and d-5, but not on d-1. Gibberellins A5 and A7 were found to be soluble in chloroform at pH 2.5 and 5.0, and A7 was soluble at pH 6.0. The possible significance of neutral gibberellin-like substances in the gibberellin economy of plants is discussed.