Strong correlation of wild barley (Hordeum spontaneum) population structure with temperature and precipitation variation

Abstract

In this study, we present the genetic analysis of a new collection of wild barley (Hordeum spontaneum) using 42 simple sequence repeat (SSR) markers that represent the seven chromosomes. The Barley1K (B1K) infrastructure consists of 1020 accessions collected in a hierarchical sampling mode (HSM) from 51 sites across Israel and represents the wide adaptive niche of the modern barley's ancestor. According to the genetic structure analysis, the sampled sites can be divided into seven groups, and sampled microsites located on opposing slopes or in different soil types did not show significant genetic differentiation. Although the genetic analysis indicates a simple isolation-by-distance model among the populations, examination of the genetic populations' structure with abiotic parameters in an ordination analysis revealed that the combination of elevation, mid-day temperature and rainfall explains a high proportion of the variance in the principal components analysis. Our findings demonstrate that the current populations have therefore been shaped and distinguished by non-selective forces such as migration; however, we suggest that aridity and temperature gradients played major roles as selective forces in the adaptation of wild barley in this part of the Fertile Crescent. This unique collection is a prelude for the investigation of the molecular basis underlying plant adaptation and responsiveness to harsh environments.

DNA sequence variation of wild barley Hordeum spontaneum (L.) across environmental gradients in Israel

“…The methods used suggested different numbers of clusters (K ¼ 3 or K ¼ 8 with STRUCTURE and K ¼ 4 with DAPC), similar to previous analyses using other marker types (Hubner et al, 2009(Hubner et al, , 2012. The present sample is unbalanced because more than half of the accessions originated from EC1, and both clustering methods separate primarily the accessions from the different slopes within EC1 for lower values of K, which demonstrates the high diversity present in EC1 accessions.…”

“…Differences from previous studies indicate an effect of marker types, collections and temporal changes in the population (Nevo et al, 2012). Future studies of wild barley adaptation should be carried out with additional samples around microsites such as the EC and be combined them with large systematic collections like the Barley1K (Hubner et al, 2009) to put the local patterns of genetic variation into a broader geographic context. DATA ARCHIVING Sequence data were submitted to NCBI GenBank under accession numbers KC471630-KC473154.…”

“…Also, EC1 accessions grouped together with the other accessions from North Israel, whereas the accessions from the sampling sites in Central or Southern Israel were clustered separately. This grouping reflects the ecogeographic differences between the mesic North and xeric South and corresponds with the clustering into Mediterranean (Northern), coastal and desert wild barley (Hubner et al, 2009(Hubner et al, , 2012. As an exception, the Mt.…”

“…Common garden experiments suggested local adaptation to different levels of rainfall that affected traits like flowering time, seed size, seed germination and others (Volis et al, 2002b;Hubner et al, 2012). The genetic population structure overlaps with the major ecogeographic regions of the Levant area and may result from adaptation to different climatic regions (Hubner et al, 2009(Hubner et al, , 2012(Hubner et al, , 2013.…”

Transcriptome profiling reveals mosaic genomic origins of modern cultivated barley

“…Recent advances in the characterization and quantification of transcriptome with RNA-Seq have been made in rice (18), maize (19), and barley (20). In view of the large genome of barley and the wide genetic diversity of wild barley (4,14,21), RNA-Seq has become a very effective and powerful technology in generating comprehensive transcriptome profiles (22).…”