Adaptation and diversity along an altitudinal gradient in Ethiopian barley (Hordeum vulgare L.) landraces revealed by molecular analysis

Abstract

BackgroundAmong the cereal crops, barley is the species with the greatest adaptability to a wide range of environments. To determine the level and structure of genetic diversity in barley (Hordeum vulgare L.) landraces from the central highlands of Ethiopia, we have examined the molecular variation at seven nuclear microsatellite loci.ResultsA total of 106 landrace populations were sampled in the two growing seasons (Meher and Belg; the long and short rainy seasons, respectively), across three districts (Ankober, Mojanawadera and Tarmaber), and within each district along an altitudinal gradient (from 1,798 to 3,324 m a.s.l). Overall, although significant, the divergence (e.g. FST) is very low between seasons and geographical districts, while it is high between different classes of altitude. Selection for adaptation to different altitudes appears to be the main factor that has determined the observed clinal variation, along with population-size effects.ConclusionsOur data show that barley landraces from Ethiopia are constituted by highly variable local populations (farmer's fields) that have large within-population diversity. These landraces are also shown to be locally adapted, with the major driving force that has shaped their population structure being consistent with selection for adaptation along an altitudinal gradient. Overall, our study highlights the potential of such landraces as a source of useful alleles. Furthermore, these landraces also represent an ideal system to study the processes of adaptation and for the identification of genes and genomic regions that have adaptive roles in crop species.

Population Structure of Barley Landrace Populations and Gene-Flow with Modern Varieties

“…This is in agreement with what has been observed in different species where such comparisons have been made directly [5] or indirectly [8], [23]. This is further confirmation that in-situ conservation of landrace populations is an effective and valuable strategy to preserve crop genetic resources [7].…”

Low Genetic Differentiation and Evidence of Gene Flow among Barley Landrace Populations in Tunisia

“…Nielsen et al (2014), Das et al (2013), and Montilla-Bascón et al (2013) indeed reported lower gene diversity in wheat (0.384), rice (0.547) and oat (0.29), respectively. Conversely, R ST may reveal better differentiation, as it is independent of the stepwise mutation process (Hadado et al, 2010). In our study, the private alleles to the five northern populations (Beja, Kef, Siliana, Zaghouan, and Bizerte) represent 56% of the total private alleles assessed in the 11 populations.…”

“…The total number of effective alleles was 92.25. Comparable levels of low heterozygosity were reported when microsatellites were applied for Ethiopian (Hadado et al, 2010;Samberg et al, 2013) and Moroccan (Jensen et al, 2013) barley landraces. A total of 227 genotypes were scored with an average of 10.81 genotypes per locus (Table 3).…”

“…The loci EBmac0970 the loci Bmac0040 (0.0267), whereas the loci Bmag0139 presented the highest PI value (0.240). Expected heterozygosity (H e ) was 0.71 for Ethiopian landscape barley (Hadado et al, 2010), whereas a gene diversity value of ~0.6 was observed for Moroccan barley landraces (Jensen et al, 2013). The observed heterozygosity (H o ) across loci ranged from 0 (HVM36, HVM67, Bmac0093, Bmac0154, Bmag0218, EBmac0684, Bmac0113, Bmag0136, and EBmac 0970) to 1 (WMC1E8), with a mean of 0.12.…”

European Phaseolus coccineus L. landraces: Population Structure and Adaptation, as Revealed by cpSSRs and Phenotypic Analyses

“…In plants with a wide distribution, phenological traits and adaptive molecular variance can be expected to vary clinally along climatic gradients [43], [44]. As examples, latitudinal clines in flowering time have been predicted and shown in accessions of the annual Arabidopsis thaliana [43].…”