Gibberellins and carotenoids in the wild type and mutants of Gibberella fujikuroi

Abstract

A new screening procedure was used to isolate 14 gib mut ts of Gi!'berella_ fujikurof wit modi cations the production of gibberellins. The production of carotenmds and g bberellms was mvestlgated m the gib mutants and in representative car mutants with various modifications of carotenoid biosynthesis. The determinations of gibberellins were carried out with a simplified ftuorescence method. One of the mutants lacked both gibberellins and carotenoids. In many mutants the two pathways compensated each other: an increase in the production of one group of compounds was accompanied by a decrease in the production of the other Under certain conditions the compensation was quantitative when the output of the two pathways was meas¿red in moles of the common precursor, geranylgeranyl pyrophosphate. a-Picoline, an inhibi or of lycopene cyclase in G.fujikuroi, inhibits gibberellin biosynthesis. Other agents !hat atfect t e ac umulatlon. of carotenoids have no noticeable etfect on the accumulation of gibberellins; such as the case wath dtphenylamt?e and p-ionone, two inhibitors of phytoene dehydrogenation, and visible light, which stimulates carotenogenestS