Abstract
Polyamines (PAs) are essential metabolites in plants performing multiple functions during growth and development. Copper-containing amine oxidases (CuAOs) catalyse the catabolism of PAs and in
are encoded by a gene family. Two mutants of one gene family member,
, showed delayed seed germination, leaf emergence, and flowering time. The height of the primary inflorescence shoot was reduced, and developmental leaf senescence was delayed. Siliques were significantly longer in mutant lines and contained more seeds. The phenotype of
over-expressors was less affected. Before flowering, there was a significant increase in putrescine in
mutant leaves compared to wild type (WT), while after flowering both spermidine and spermine concentrations were significantly higher than in WT leaves. The expression of GA (gibberellic acid) biosynthetic genes was repressed and the content of GA
, GA
, GA
, GA
, and GA
was reduced in the mutants. The inhibitor of copper-containing amine oxidases, aminoguanidine hydrochloride, mimicked the effect of
mutation on WT seed germination. Delayed germination, reduced shoot height, and delayed flowering in the mutants were rescued by GA
treatment. These data strongly suggest
is an important gene regulating PA homeostasis, and that a perturbation of PAs affects plant development through a reduction in GA biosynthesis.