α-Galactosidase activity and carbohydrate mobilization in seeds of Dalbergia nigra (Vell.) Allemão ex Benth. : Fabaceae (brazilian rosewood) during germination

Abstract

Complex substances are converted by enzyme action into soluble molecules during the germination process, and these are in turn translocated to the growing plant embryo, serving as an energy source or physical structure. With the objective of quantifying α-galactosidase enzyme activity as well as mono- and oligosaccharide mobilization during germination, this study was conducted using Brazilian rosewood seeds. Seeds were kept in a germinator at 25ºC under continuous light for evaluation of radicle emergence (protrusion) over a period of 10 days. Mono- and oligosaccharide contents and also the specific activity of α–galactosidase enzyme were quantified on days zero, one, three and five. There was mobilization of glucose and mannose stored in cotyledons, and also of xylose in cotyledons and in the embryo in the first three days of germination. Rhamnose contents increased in cotyledons and in the embryonic axis. Raffinose was the initially used oligosaccharide, both in the embryonic axis and in cotyledons, while sucrose accumulated in both. Enzyme activity varied throughout, with greater specific activity on day one of imbibition, both in cotyledons and in the embryonic axis.