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Nonstructural carbohydrates were determined in both embryo and endosperm of dormant (nongerminating) and afterripened (germinating) intact caryopses of wild oat (Avena fatua L.). No changes in endosperm starch or soluble sugar were observed at the onset of germination (18 h). No changes in glucose, fructose, sucrose or starch within dormant or afterripened embryos correlated with onset of visual germination. In afterripened embryos, depletion of raffinose (18 h), stachyose (18 h) and galactose (24 h) was correlated with germination. In contrast, raffinose-family oligosaccharide levels in dormant embryos remained constant for 7 days following imbibition. Germination of isolated dormant embryos on 88 mM galactose-containing media was accompanied by decreased endogenous levels of raffinose and stachyose. Isolated embryos from dormant caryopses incorporated 14C from 14C-fructose into both raffinose and stachyose during 24 h of imbibition. In contrast, no 14C incorporation into stachyose was observed in embryos from afterripened caryopses. No 14C incorporation into raffinose was observed at 18 and 24 h. When in vitro activities of α galactosidase were measured, no temporal differences between dormant or afterripened caryopses were detected in either embryo or endosperm tissue. Although the mechanism associated with differences in utilization of raffinose and stachyose is yet unidentified, alterations in raffinose-family oligosaccharide metabolism in the embryo appear to be a unique prerequisite for afterripening-induced germination.

carbohydrate, germination, Afterripening, Avena fatua, dormancy, raffinose, seed, stachyose, wild oat

Publication DOI: 10.1111/j.1399-3054.1993.tb05492.x
Journal NLM ID: 1256322
Publisher: Copenhagen: Scandinavian Society For Plant Physiology
Institutions: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA, Departmentt of Agronomy, Purdue University, West Lafayette, IN, USA
Methods: enzymatic assays, bioassays