Evidence for genetic differentiation and divergent selection in an autotetraploid forage grass (Arrhenatherum elatius)

Abstract

The use of local provenances in restoration, agriculture and forestry has been identified as measure to sustain biological diversity and to improve local productivity. However, the delineation of regional provenances is challenging because it requires the identification of well-defined groups based on spatiogenetic differentiation and/or the evidence of local adaptation. In this study, we investigate genetic variation at 186 AFLP loci in 46 European accessions of the important grassland species Arrhenatherum elatius and ask (1) whether genetic variation within accessions differs between European geographical regions; (2) at which spatial scale populations are structured across Europe and (3) whether putatively adaptive markers contribute to this pattern and whether these markers can be related to climatic site conditions. Basic expectations of population genetics are likely to be altered in autotetraploid species, thus, we adopted a band-based approach to estimate genetic diversity and structuring. Compared to other grasses A. elatius showed high genetic diversity and considerable differentiation among accessions (Phi(ST) = 0.24). Accessions separated in a Western European and a Central/Eastern European group, without further structure within groups. A genome scan approach identified four potentially adaptive loci, whose band frequencies correlated significantly with climatic parameters, suggesting that genetic differentiation in A. elatius is also the result of adaptive processes. Knowledge on adaptive loci might in the long run also help to adapt ecosystems to adverse climate change effects through assisted migration of ecotypes rather than introduction of new species.

Assessment of provenance delineation by genetic differentiation patterns and estimates of gene flow in the common grassland plant Geranium pratense

“…However, with only one significant out of eight correlations we found little evidence for adaptive differentiation caused by climatic selection, which has been identified as a driving force of population differentiation on various scales (e.g. Michalski et al 2010, Shi et al 2011). However, it cannot be excluded that other environmental variables (e.g.…”

“…For all samples, total genomic DNA was extracted using the DNeasy 96 Plant extraction kit (QIAGEN). AFLP analysis was done as described in Michalski et al (2010). After primer screening the four following primer combinations were selected: 5 0 -FAM-GACTGCGTACCAATTCAAC-3 0 and 5 0 -GATGAGTCCTGAGTAACAG-3 0 ; 5 0 -VIC-GACT GCGTACCAATTCACA-3 0 and 5 0 -GATGAGTCCTGAGT AACTT-3 0 ; 5 0 -NED-GACTGCGTACCAATTCAAG-3 0 and 5 0 -GATGAGTCCTGAGTAACAG-3 0 , and 5 0 -PET-GACT GCGTACCAATTCAGG-3 0 and 5 0 -GATGAGTCCTGAG TAACAG-3 0 .…”

“…AFLP markers (amplified fragment lengths polymorphisms) have helped to identify large scale differentiation patterns (Michalski et al 2010), to describe the spatial genetic structure within populations (Eckstein et al 2006), to infer the mating system (Peters et al 2009) and dispersal distances (Hardy et al 2006), and to demonstrate adaptive differentiation (Herrera and Bazaga 2008). Hence, AFLPs are a versatile tool for studying relevant patterns for the delineation of local provenances (Krauss and Koch 2004;Bussell et al 2006).…”

Analysis of genetic diversity inElytrigia repensgermplasm using intersimple sequence repeat (ISSR) markers

“…Yang et al (2007) found a significant correlation between the geographical and genetic distances among the populations of D. sinensis (p < 0.05) (Yang et al 2007). However, Michalski et al (2010) found the genetic and geographical distances were uncorrelated among central and eastern European accessions of A. elatius owing to the human activities in the nineteenth century (Michalski et al 2010). Therefore, the genetic isolation by distance among E. repens accessions is necessary to preserve genetic diversity and the ability to breed new varieties of E. repens in the future.…”

“…Even though the ISSR technique has some disadvantages as a dominant marker compared with SSRs and SNPs, it has been proven as an effective tool for investigation of genetic variation of species and has been widely used for evaluating plant germplasm and genetic diversity (Joshi et al 2000;Femandez et al 2002;Bornet et al 2004;Terzopoulos and Bebeli 2008;Liu et al 2009;Wang et al 2009;Michalski et al 2010). ISSR amplification is a PCR based method that can rapidly differentiate among closely related individuals and is useful to generate new DNA markers for studies on plant improvement, genomic fingerprinting, and phylogenetic analysis (Bornet and Branchard 2001;Wang et al 2009).…”