Molecular characterization of a putative sucrose:fructan 6-fructosyltransferase (6-SFT) of the cold-resistant Patagonian grass Bromus pictus associated with fructan accumulation under low temperatures

DEL VISO, F; PUEBLA, A.F.; FUSARI, C.M.; CASABUONO, A.C.; CUOTO, A.S.; PONTIS, H.G.; HOPP, H.E.; HEINZ, R.A.

PLANT AND CELL PHYSIOLOGY

Oxford University Press

Lugar: Oxford; Año: 2009 vol. 50 p. 489 - 503

0032-0781

Fructans are fructose polymers synthesized from sucrose in the plant vacuole. They represent short and long term carbohydrate reserves and have been associated to abiotic stress tolerance in graminean species. We report the isolation and characterization of a putative sucrose:fructan 6-fructosyltransferase (6-SFT) gene from a Patagonian grass species, Bromus pictus, tolerant to drought and cold temperatures. Structural and functional analyses of this gene were performed by Southern and northern blot. Sugar content, quality and fructosyltransferase activity were studied using by HPAEC-PAD, enzymatic and colorimetric assays. Putative 6-SFT gene had all fructosyltransferase conserved motifs and showed 90% identity at amino acid level with other 6-SFTs from winter cereals. Expression studies, sugar content and fructosyltransferase activity were performed in five sections of the leaf. Bp6-SFT was expressed predominantly in leaf bases, where FT activity and fructan content is higher. Bp6-SFT expression and accumulation of fructans showed different patterns in the evaluated leaf sections during a seven day time course experiment under chilling treatment. The transcriptional pattern suggests that B. pictus 6-SFT gene is highly expressed in basal leaf sections even under control temperate conditions, contrary to previous reports in other graminean species. Low temperatures caused an increase in Bp6-SFT expression and fructan accumulation in leaf bases. This is the first study of isolation and molecular characterization of a fructosyltransferase in a native species from the Patagonian region. Expression in heterologous systems will confirm functionality allowing future developments as generation of functional markers for assisted breeding or biotechnological applications.