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- Title
Enzymatic breakdown of raffinose oligosaccharides in pea seeds.
- Authors
Blöchl, Andreas; Peterbauer, Thomas; Hofmann, Julia; Richter, Andreas
- Abstract
Both alkaline and acidic α-galactosidases (α- d-galactoside galactohydrolases, E.C.3.2.1.22) isolated from various plant species have been described, although little is known about their co-occurrence and functions in germinating seeds. Here, we report on the isolation of two cDNAs, encoding for α-galactosidases from maturing and germinating seeds of Pisum sativum. One was identified as a member of the acidic α-galactosidase of the family 27 glycosyl hydrolase cluster and the other as a member of the family of alkaline α-galactosidases, which are highly homologous to seed imbibition proteins (SIPs). PsGAL1 transcripts, encoding for the ACIDIC α-GALACTOSIDASE, were predominately expressed during seed maturation and acidic enzyme activities were already present in dry seeds, showing little changes during seed germination. Compartmentation studies revealed that acidic α-galactosidases were located in protein storage vacuoles (PSVs). PsAGA1, encoding for the ALKALINE α-GALACTOSIDASE, was only expressed after radicle protrusion, when about 50% of RFOs have already been broken down. RFO breakdown was markedly decreased when the translation of the alkaline enzyme was inhibited, providing evidence that PsAGA1 indeed functioned in RFO degradation. Based on these data, we present an integrated model of RFO breakdown by two sequentially active α-galactosidases in pea seeds.
- Subjects
SEED pods; ENZYMES; PEAS; PLANT species; PLANT physiology; SEED viability; PLANT classification; PLANT embryology; OLIGOSACCHARIDES; GLUCOSIDES
- Publication
Planta: An International Journal of Plant Biology, 2008, Vol 228, Issue 1, p99
- ISSN
0032-0935
- Publication type
Article
- DOI
10.1007/s00425-008-0722-4