Sugar metabolism in developing lupin seeds is affected by a short-term water deficit |
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Authors: | Pinheiro Carla Rodrigues Ana Paula de Carvalho Isabel Saraiva Chaves Maria Manuela Ricardo Cândido Pinto |
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Institution: | Instituto de Tecnologia Química e Biológica, Apartado 127, 2781-901 Oeiras, Portugal. |
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Abstract: | 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 ( approximately 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 approximately 60% increase in stachyose and raffinose (raffinose family oligosaccharides). This increase in raffinose family oligosaccharides appears as the WD imprinting on mature seeds. |
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