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Biosynthesis of raffinose family oligosaccharides and galactosyl pinitols in developing and maturing seeds of winter vetch [Vicia villosa Roth.]

100%

Lahuta L. B.

Acta Societatis Botanicorum Poloniae

2006

tom 75

nr 3

219-227

Changes in the accumulation of two types of α-D-galactosides: raffinose family oligosaccharides and galactosyl pinitols were compared with changes in the activities of galactosyltransferases during winter vetch (Vicia villosa Roth.) seed development and maturation. Occurrence of galactinol and raffinose in young seeds and changes in activities of galactinol synthase and raffinose synthase during seed development indicated that formation of raffinose oligosaccharides (RFOs) preceded synthesis of galactopinitols. Although transfer of galactose residues into raffinose oligosaccharides increased as seeds were maturing, at late stages of seed maturation the accumulation of galactopinitols was preferred to that of RFOs. In the present study, activities of enzymes transferring galactose moieties from galactinol to D-pinitol forming galactopinitol A, and further transfer of galactose moieties from galactinol to mono- and di-galactopinitol A were detected throughout seed development and maturation. This is a new observation, indicating biological potential of winter vetch seeds to synthesize mono-, di- and tri-galactosides of D-pinitol in a pathway similar to RFOs. The pattern of changes in activities of stachyose synthase and enzymes synthesizing galactopinitols (named galactopinitol A synthase and ciceritol synthase) suggests that formation of stachyose, mono- and di-galactopinitol A (ciceritol) is catalyzed by one enzyme. High correlation between activities of verbascose synthase and enzyme catalyzing synthesis of tri-galactopinitol A from galactinol and ciceritol (named tri-galactopinitol A synthase) also suggests that biosynthesis of both types of tri-galactosides was catalyzed by one enzyme, but distinct from stachyose synthase. Changes in concentrations of galactosyl acceptors (sucrose and D-pinitol) can be a factor which regulates splitting of galactose moieties between both types of galactosides in winter vetch seeds.

High concentrations of D-pinitol or D-chiro-inositol inhibit the biosynthesis of raffinose family oligosaccharides in maturing smooth tare [Vicia tetrasperma [L.] Schreb.] seeds

100%

Lahuta L. B., Gorecki R. J., Horbowicz M.

Acta Physiologiae Plantarum

2005

tom 27

nr 4A

In the present study we have investigated the effect of exogenous cyclitols on accumulation of their galactosides and raffinose family oligosaccharides (RFOs) in maturing smooth tare (Vicia tetrasperma [L.] Schreb) seeds. Feeding D-pinitol to pods of smooth tare increased the amount of free D-pinitol and its galactosides: galactopinitol A, galactopinitol B, di- and trigalactopinitol A in seeds. Similarly, feeding D-chiro-inositol, which does not occur naturally in Vicia seeds, resulted in the transport of this cyclitol in the seed, and caused accumulation of high levels of D-chiro-inositol galactosides (fagopyritol B1, B2 and B3). Accumulation of both cyclitols and their galactosides drastically reduced accumulation of verbascose and, to a lesser extent, stachyose and di-galactosyl- myo-inositol. Feeding D-chiro-inositol also decreased accumulation of di- and tri-galactosyl pinitols, naturally occurring in seeds. Inhibition of RFOs accumulation by elevated levels of free cyclitols indicates competition between biosynthesis of both types galactosides, and similarity of both biosynthetic pathways in smooth tare seeds.

Ograniczanie wyników

1 Acta Physiologiae Plantarum

1 Acta Societatis Botanicorum Poloniae

2 Lahuta L. B.

1 Gorecki R. J.

1 Horbowicz M.

1 2006

1 2005

Wyniki wyszukiwania

Biosynthesis of raffinose family oligosaccharides and galactosyl pinitols in developing and maturing seeds of winter vetch [Vicia villosa Roth.]

High concentrations of D-pinitol or D-chiro-inositol inhibit the biosynthesis of raffinose family oligosaccharides in maturing smooth tare [Vicia tetrasperma [L.] Schreb.] seeds