Genetic engineering of beta-glucan contents of oat

The health benefits of oat (Avena sativa L.) are mainly associated with its mixed-linked beta-glucan. Mixed-linked beta-glucan is not metabolised by digestive enzymes. It lowers the cholesterol levels of blood and balances the glucose and insulin contents of serum after meals. These physiological effects reduce the risks of cardiovascular diseases. Our aim is to increase the beta-glucan content of Finnish oat cultivars through genetic engineering. The ultimate aim is to use plant-derived genes to elevate the beta-glucan content of oat to levels not obtainable through traditional plant breeding methods. Embryogenic cell cultures were started from mature embryos of oat cultivars ‘Aslak’, ‘Veli’ and ‘Kolbu’. Microscopic- and HPLC-analysis of beta-glucan of seeds, apical meristems and cell cultures were carried out. Gene transfer of microbial 1,3-beta-glucan synthases by particle bombardment was performed. The beta-glucan was mainly localized in subaleurone layers of oat seeds by Calcofluor staining. The molecular weight of oat seed beta-glucan was ca. 2 000 000 and the amount varied from 40 to 60 g/kg. In apical meristems trace amounts of beta-glucan were observed. In cell cultures the molecular weight of the beta-glucan was ca. 200 000 and the amount varied from 2 to 3 g/kg. Gene transfer experiments with microbial 1,3-beta-glucan synthase genes have been started in order to evaluate their effect on beta-glucan contents of oat cell lines. The cloning of plant beta-glucan synthase genes is on the way. References Salmenkallio-Marttila, M., K. Katina & K. Autio, 2002. Effects of bran fermentation on quality and microstructure of high-fiber wheat bread. Cereal Chem. 78: 429-435. Suortti, P. 1993. Size-exclusion chromatographic determination of beta-glucan with postcolumn reaction detection. J. Chrom. 632: 105-110.