Farmers without borders—genetic structuring in century old barley (Hordeum vulgare)

Abstract

The geographic distribution of genetic diversity can reveal the evolutionary history of a species. For crop plants, phylogeographic patterns also indicate how seed has been exchanged and spread in agrarian communities. Such patterns are, however, easily blurred by the intense seed trade, plant improvement and even genebank conservation during the twentieth century, and discerning fine-scale phylogeographic patterns is thus particularly challenging. Using historical crop specimens, these problems are circumvented and we show here how high-throughput genotyping of historical nineteenth century crop specimens can reveal detailed geographic population structure. Thirty-one historical and nine extant accessions of North European landrace barley (Hordeum vulgare L.), in total 231 individuals, were genotyped on a 384 single nucleotide polymorphism assay. The historical material shows constant high levels of within-accession diversity, whereas the extant accessions show more varying levels of diversity and a higher degree of total genotype sharing. Structure, discriminant analysis of principal components and principal component analysis cluster the accessions in latitudinal groups across country borders in Finland, Norway and Sweden. F ST statistics indicate strong differentiation between accessions from southern Fennoscandia and accessions from central or northern Fennoscandia, and less differentiation between central and northern accessions. These findings are discussed in the context of contrasting historical records on intense within-country south to north seed movement. Our results suggest that although seeds were traded long distances, long-term cultivation has instead been of locally available, possibly better adapted, genotypes.

Extent and pattern of genetic diversity in Ethiopian white lupin landraces for agronomical and phenological traits

“…About 90% of the landraces constituted the Cluster I and were from three bordering zones of Gojam namely: West Gojam, Awi, and Bahir Dar Zuria. This result indicates that there might have been exchange of seeds, and seed trade between farmers, and gene flow across boundaries of those areas (Forsberg et al, 2015). On the other hand, accessions from non-bordering origins were entirely constituted by a particular cluster such as landraces from South Gondar and East Gojam constituent cluster IV, and those from North Gondar and North Omo form cluster VIII.…”

Exploring Fennoscandian agricultural history through genetic analysis of aged crop materials

“…Previous studies have shown that both the barley and rye grown in this region are genetically distinct from the ones grown in southern and central Europe (Jones, et al, 2011;Hagenblad, et al, 2016). For barley, it has been shown that these structures were present already in late 19 th century (Aslan, et al, 2015;Forsberg, et al, 2015) but the time-depth of these structures beyond that has remained unknown. One of the limiting factors has been the lack of suitable historical plant materials available for genetic analysis.…”

“…Improvement effects resulted from selection and breeding using only a small number of plants with the desired traits, followed by seed marketing and distribution over large areas outside of the region and traditions in which the original landraces formed (Jones, et al, 2008b). Studies based on landrace materials have, for example, been used to examine local adaptation to climate (Jones, et al, 2008a;Jones, et al, 2011;Aslan, et al, 2015) and population structures in order to determine the origins and spread of different crops on local scale (Pecetti and Damania, 1996;Papa, et al, 1998;Leino, et al, 2013;Forsberg, et al, 2015) or over larger distances (Hunt, et al, 2011;Jones, et al, 2011;Oliveira, et al, 2012a).…”

Population genetic structure in Fennoscandian landrace rye (Secale cereale L.) spanning 350 years

“…Genetic analysis of unimproved domesticated cultivars, known as landraces, of rye preserved in genebanks has shown much more variation within the landraces than among them (Persson and von Bothmer 2002;Hagenblad et al 2016). Compared to Fennoscandian landrace barley (Forsberg et al 2015) rye from this region shows little differentiation between landraces from different geographic areas. It has been suggested that when a wind pollinated, outbreeding crop such as rye is grown to the extent it has been cultivated in Fennoscandia, gene flow between fields and areas has been sufficient to homogenize the genetic diversity (Hagenblad et al 2016).…”

“…The distribution of genetic diversity in landraces may be seen as historical records of former trade routes and social interactions (Jones et al 2008;Forsberg et al 2015). In the sixteenth and seventeenth century the government supported migration of farmers from Finland to scarcely populated forest areas in the middle of Sweden, known to this day as Finnmarken (Myrdal and Söderberg 1991).…”