SSR and SNP diversity in a barley germplasm collection

Sets of microsatellites extracted from both a genomic library (gSSRs) and from expressed sequence tag sequence (eSSRs), and single nucleotide polymorphisms (SNPs) were applied to assess the levels of genetic diversity in a sample of 70 barley accessions, originating from 28 countries in Asia, Africa, the Middle East and Europe. The eSSR assays detected a mean of 9.5 alleles per locus, and the gSSRs only 5.7 alleles per locus, but the polymorphism information content values for the two assay types were indistinguishable. Strong and statistically significant correlations were observed between the eSSR and gSSR (r = 0.86, P < 0.05), the eSSR and SNP (r = 0.74, P < 0.05) and the gSSR and SNP genotypes (r = 0.67, P < 0.05). Accessions originating from the Middle East and Asia had the highest levels of genetic diversity. Pairwise genetic similarity ranged from 0.16 to 0.87 (mean 0.43), indicating that the sample was genetically diverse. When clustered on the basis of genotype, Asian and African accessions tended to be grouped together, but those originating from the Middle East were not concentrated in any particular cluster

Locating Stable Across Environment QTL Involved in the Determination of Agronomic Characters in Wheat

The International Triticeae Mapping Initiative (ITMI) recombinant inbred line (RIL) population was used to detect quantitative trait loci (QTL) underlying some key agronomic characters in bread wheat ( Triticum aestivum L.). Trait measurements were taken from five independent field experiments performed in Serbia. Stable across environment QTL involved in the determination of heading/flowering time and ear morphology/grain yield were detected on, respectively, chromosome arms 2DS and 4AL. These map locations are consistent with those obtained where the same population has been grown in contrasting geographical sites. However, as a result of QTL x environment interactions, not all these QTL are expressed in all environments. Nevertheless the ( pleiotropic) effect on ear morphology appears to be expressed in almost all environments, and so represents a high value target for wheat improvement

Genomics of tolerance to abiotic stress in the Triticeae

Genomics platforms offer unprecedented opportunities to identify, select and in some cases clone the genes and the quantitative trait loci (QTLs) that govern the tolerance of Triticeae to abiotic stresses and, consequently, grain yield. Transcriptome profiling and the other \u201comics\u201d platforms provide further information to unravel gene functions and validate the role of candidate genes. This review provides a synopsis of the main results on the studies that have investigated the genomics of Triticeae crops under conditions of abiotic constraints. With their rich biodiversity and high functional plasticity in response to environmental stresses, Triticeae crops provide an ideal ground for taking full advantage of the opportunities offered by genomics approaches. Ultimately, the practical impact of the knowledge and materials generated through genomics-based approaches will depend on their integration and exploitation within the extant breeding programs