Gibberellins in endosperm and embryos of Marah macrocarpus

Abstract

Endogenous gibberellins (GAs) have been identified by GC-mass spectrometry in homogenates of the endosperm and embryos of Marah macrocarpus seeds, before and after fractionation of proteins by ammonium sulphate precipitation, followed by Sephadex G-25 filtration. The unfractionated endosperm homogenate contained GA 3, GA 4, GA 4-diacid, GA 7, GA 7-isolactone, GA 7-diacid, GA 25, GA 37, GA 43, GA 46, GA 62 and the putative 2β,12α-dihydroxyGA 25, 12α-hydroxyGA 43 and 2β-hydroxyGA 84; the amounts of these GAs were 2–100 μg g −1, except for GA 3 and GA 62, which were present in much lower amounts. The fractionated endosperm homogenate still contained GA 4, GA 7, GA 7-isolactone, GA 25, 2β,12α-dihydroxyGA 25, and GA 46, but in reduced amounts (⩽1 μg g −1 endosperm). The unfractionated embryo homogenate contained comparable amounts of the same GAs, as in the unfractionated endosperm homogenate, except for the absence of GA 7-diacid, GA 62, the putative 2β,12α-(OH) 2GA 25 and the putative 12α-OHGA 43; GA 1 and GA 13 were also present. In contrast to the endosperm, no GAs were detected in the fractionated embryo homogenate.