Improving oat Beta-glucan content by biotechnological methods

Oat (Avena sativa L.) products lower the blood cholesterol level, a risk factor in heart diseases. Moreover, Beta-glucan also helps to normalize the postprandial blood glucose level and reduces the risk of colon cancer. These health benefits are mainly associated with high levels of mixed-linked (1,3)-(1,4)-Beta-D-glucan, a dietary fiber of which the main part is soluble. The amount of Beta-glucan is dependent on the genotype and thus can be increased by cultivar breeding. In this study, modern biotechnology tools were applied in order to breed high Beta-glucan oat cultivars for food and processing purposes. To understand the inheritance of Beta-glucan content in oat and to enable DNA-marker-assisted selection in oat cultivar breeding, a genetic linkage map was constructed for a Nordic oat cross. An Aslak x Matilda mapping population of 137 totally homozygous DH-lines was produced by anther culture. The linkage map consisted of over 600 PCR-based DNA-markers, including microsatellites, RAPDs, REMAPs, ISSRs, SRAPs and AFLPs. The QTL analysis showed two QTLs associated with Beta-glucan content. Together they explained about 37% of the variation in the DH lines. In both chromosomal regions alleles from Aslak had a favorable effect on Beta-glucan content. On the basis of the results, markers tightly linked to the genes themselves may be developed for DNA-marker assisted selection of high Beta-glucan content containing oat breeding lines. QTLs were located also for other traits of interest. Another aim was to modify the Beta-glucan content of Finnish oat cultivars through genetic engineering. Embryogenic cell cultures were started from mature embryos of oat cultivars Aslak, Veli, and Kolbu. A microbial 1,3-Beta-glucan synthase was transferred to oat cell lines by particle bombardment and transgenic plants were regenerated. The expression of the microbial gene in transgenic cell cultures was demonstrated by semi-quantitative RT-PCR. The 1,3-1,4-beta-glucan amounts were reduced and the molecular weight of the mixed-linked Beta-glucan differed in some transgenic seed lines when compared to non-transgenic control seeds. The analyses of 1,3-beta-glucan contents of transgenic cell lines and seeds is ongoing. A basis exists for modifying oat Beta-glucan contents through genetic engineering.