Wild barley, Hordeum spontaneum C. Koch, is the progenitor of cultivated barley, Hordeum vulgare. The centre of diversity is in the Fertile Crescent of the Near East, where wild barley grows in a wide range of conditions (temperature, water availability, day length, etc.). The genetic diversity of 39 wild barley genotypes collected from Israel, Turkey and Iran was studied with 33 SSRs of known map location. Analysis of molecular variance (AMOVA) was performed to partition the genetic variation present within from the variation between the three countries of origin. Using classification tree analysis, two (or three) specific SSRs were identified which could correctly classify most of the wild barley genotypes according to country of origin. Associations of SSR variation with flowering time and adaptation to site-of-origin ecology and geography were investigated by two contrasting statistical approaches, linear regression based on SSR length variation and linear regression based on SSR allele class differences. A number of SSRs were significantly associated with flowering time under four different growing regimes (short days, long days, unvernalised and vernalised). Most of the associations observed could be accounted for by close linkage of the SSR loci to earliness per se genes. No associations were found with photoperiodic and vernalisation response genes known to control flowering in cultivated barley suggesting that different genetic factors may be active in wild barley. Novel genomic regions controlling flowering time in wild barley were detected on chromosomes 1HS, 2HL, 3HS and 4HS. Associations of SSRs with site-of-origin ecological and geographic data were found primarily in genomic regions determining plant development. This study shows that the analyses of SSR variation by allele class and repeat length are complementary, and that some SSRs are not necessarily selectively neutral.
Bibliographical noteFunding Information:
We are grateful to Rhonda Meyer, George Young, Joanne Russell (SCRI, Dundee, Invergowrie, UK), Jack Staub (USDA, University of Wisconsin, Madison, WI) and Dave Laurie (John Innes Centre, Norwich, UK) for valuable help and advice. V.I. holds a Marie-Curie fellowship as part of the EC programme for Training and Mobility of Researchers (TMR). SCRI receives grants-in-aid from the Scottish Executive Rural Affairs Department (SERAD). E.N. wishes to thank the Israeli Discount Bank Chair of Evolutionary Biology and the Ancel-Teicher Research Foundation for Genetics and Molecular Evolution for financial support.
- Classification tree
- Hordeum spontaneum
- Regression analysis
ASJC Scopus subject areas
- Agronomy and Crop Science
- Plant Science