Sugar metabolism in developing lupin seeds is affected by a short-term water deficit

Pinheiro, Carla; Rodrigues, Ana Paula; Carvalho, Isabel Saraiva de; Chaves, Maria Manuela; Ricardo, C. P.

http://hdl.handle.net/10400.1/1861

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Authors

Pinheiro, Carla

Rodrigues, Ana Paula

Carvalho, Isabel Saraiva de

Chaves, Maria Manuela

Ricardo, C. P.

Abstract(s)

A short-term water deficit (WD) imposed during the pre-storage phase of lupin seed development [15–22 d after anthesis (DAA)] accelerated seed maturation and led to smaller and lighter seeds. During seed development, neutral invertase (EC 3.2.1.26) and sucrose synthase (EC 2.4.1.13) have a central role in carbohydrate metabolism. Neutral invertase is predominant during early seed development (up to 40 DAA) and sucrose synthase during the growing and storage phase (40–70 DAA). The contribution of acid invertase is marginal. WD decreased sucrose synthase activity by 2-fold and neutral invertase activity by 5–6-fold. These changes were linked to a large decrease in sucrose (∼60%) and an increase of the hexose:sucrose ratio. Rewatering restored sucrose synthase activity to control levels while neutral invertase activity remained depressed (30–60%). A transient accumulation of starch observed in control seeds was abolished by WD. Despite the several metabolic changes the final seed composition was largely unaltered by WD except for ∼60% increase in stachyose and raffinose (raffinose family oligosaccharides). This increase in raffinose family oligosaccharides appears as the WD imprinting on mature seeds.