Soluble sugars and flatulence-producing oligosaccharides in maturing yellow lupin (Lupinus luteus L) seeds

The flatulence-producing soluble oligosaccharides are an important component of lupin seeds and were assayed to establish the pattern of their accumulation in relation to germinability during seed development and maturation. Maturing yellow lupin cv. Juno seeds were harvested at 5-day intervals from 15 to 45 days after flowering (DAF). Seed fresh mass increased to a maximum at 35 DAF followed by a decrease when axis and cotyledon tissues changed colour from green to yellow. Maximum seed fresh mass corresponded to the maximum seed size. Seed dry mass continuously increased until 40 DAF. About 75% of mature seed dry mass was in cotyledons, 22% in testa, and 3% in axis. Maximum seed germinability occurred at 45 DAF after maximum seed dry mass and desiccation. Maturing yellow lupin seeds were desiccation tolerant. Mature dry seeds contained 10.9% oligosaccharides and 1.5% sucrose. During seed growth stachyose accumulation preceded accumulation of raffinose and verbascose. The highest rate of oligosaccharide accumulation appeared during seed desiccation and correlated with the acquisition of the ability to germinate. The sucrose:oligosaccharide ratio continuously decreased reaching 0.13 in mature seeds. Accumulation of oligosaccharides in maturing yellow lupin seeds is associated with seed germinability and seed desiccation tolerance.