Exploring Swedish Oat (Avena sativa) Genetic History - from AD 1440 to today

Abstract: Oats (Avena sativa) have been one of the most important cereals in Swedish crop history, completely dominating domestic cereal production in the 19th and early 20th centuries. During this time, oats were mainly used as horse feed and since then, production has decreased with decreased use of horses. Oats have recently been rediscovered as a source of plant-based protein with several health benefits, and due to the low environmental requirements and effectiveness in cereal crop rotation, oats are yet again increasing in popularity. For future development of oat cultivars, insight into oat genetics and genomic history of oats is required. In this study, 84 archeological oat grains (1440-1766 AD) originating from desiccated and waterlogged sources in southern Sweden were analyzed to understand their genetic history. Next generation sequencing (NGS) of extracted DNA from individual grains revealed that the samples had varying oat alignment success, ranging from 0.01 - 34.38% (average: 9.00%). Through metagenomic analysis, it was concluded that, even though a large part of the acquired reads were bacterial, the endogenous oat content was enough to enable deeper bioinformatic analysis. Through Kompetitive Allele Specific PCR (KASP) genotyping, the genetic and geographic structuring was investigated by comparison with 343 previously genotyped 19th century oat landrace grains. Results showed that ancient landraces share genetic similarity with historical landraces and modern improved cultivars, implying that the with the introduction of improved cultivars, they were incorporated into ancient landraces, possibly to increase local adaptation. The analyses revealed a large within-accession variation in all results. An attempt was made to understand the source of this variation, but no pre-extraction parameters that increase sample success were distinguishable. With this study, it was shown that genotyping, sequencing and bioinformatic analysis of ancient oat samples is possible, and can be used to understand oat genetic history.