Competition among eight Rhynchosporium secalis isolates was assessed during parasitic and saprophytic phases of the disease cycle in field experiments conducted at two locations and over two growing seasons. The eight isolates were inoculated onto six barley populations exhibiting varying degrees of resistance. Microsatellite analysis of 2,866 isolates recovered from the field experiments showed significant, and sometimes opposite, changes in the frequencies of R. secalis genotypes during the growing season (parasitic phase) and between growing seasons (saprophytic phase). Isolates that showed the most complex virulence in greenhouse seedling assays had the lowest fitness in the field experiment. Significant differences in isolate fitness were found on different host populations and in different environments. Selection coefficients were large, indicating that evolution can occur rapidly in field populations. Although inoculated isolates had the lowest overall fitness on the moderately resistant landrace cv. Arabi Aswad, some isolates were more virulent and consistently increased in frequency on this landrace, suggesting a risk of directional selection and possible erosion of the resistance following its widespread deployment in monoculture. These results provide the first direct evidence that R. secalis pathogen genotypes differ in their saprophytic ability and parasitic fitness under field conditions.

Multi-environment trials represent a highly valuable tool for the identification of the genetic bases of crop yield potential and stress adaptation. A Diversity Array Technology®-based barley map has been developed in the ‘Nure’ × ‘Tremois’ biparental Doubled Haploid population, harbouring the genomic position of a gene set with a putative role in the regulation of flowering time and abiotic stress response in barley. The population has been evaluated in eighteen location-by-year combinations across the Mediterranean basin. QTL mapping identified several genomic regions responsible for barley adaptation to Mediterranean conditions in terms of phenology, grain yield and yield component traits. The most frequently detected yield QTL had the early flowering HvCEN_EPS2 locus (chromosome 2H) as peak marker, showing a positive effect from the early winter parent ‘Nure’ in eight field trials, and explaining up to 45.8 % of the observed variance for grain yield. The HvBM5A_VRN-H1 locus on chromosome 5H and the genomic region possibly corresponding to PPD-H2 on chromosome 1H were significantly associated to grain yield in five and three locations, respectively. Environment-specific QTLs for grain yield, and clusters of yield component QTLs not related to phenology and or developmental genes (e.g. on chromosome 4H, BIN_09) were observed as well. The results of this work provide a valuable source of knowledge and tools for both explaining the genetic bases of barley yield adaptation across the Mediterranean basin, and using QTL-associated markers for MAS pre-breeding and breeding programmes

BackgroundBarley (Hordeum vulgare L.) is a major cereal crop, which is cultivated under variable environmental conditions and abiotic stresses in marginal areas around the globe. In this study, we evaluated 150 Jordanian landraces obtained from ICARDA Gene Bank and four local checks for yield and yield components related-traits in two locations across Jordan for three growing seasons under rainfed conditions. The study aims to identify superior Jordanian barley genotypes under dry conditions, to understand the genotype × environment (G × E) interactions, to analyze stability parameters and to identify markers associated with yield and yield components under rainfed conditions.ResultsThe barley accessions exhibited significant variation for all traits studied. Three accessions with high yield, cultivar superiority and stability under specific environments were identified with accession G69 is the highest yielding and superior for Madaba and overall environments and G144 is the highest yielding at Ramtha. Accession G123 was high yielding in all environments and was stable across different environments. At the genetic level, the Jordanian landraces were found to be diverse with a clustering that was based on row-type. The GWAS analysis identified 77 significant markers-traits associations for multiple traits including grain yield (GY) with three significant QTLs located at 1H, 2H and 7H, which seem important for dry environments.ConclusionUtilizing Jordanian barley landraces can effectively improve and adapt the current barley cultivars for cultivation under environmental stresses in dry regions. Utilization of markers associated with important agronomical traits and their incorporation in breeding using marker assisted selection can improve barley tolerance to drought stress.Electronic supplementary materialThe online version of this article (10.1186/s12870-017-1140-1) contains supplementary material, which is available to authorized users.

SUMMARY23 January 2012 marked 70 years since the death of the Italian plant breeder Nazareno Strampelli (1866–1942), one of the most important plant geneticists of the 20th century. During the first 30 years of what is known as the ‘short century’, Strampelli was among the first, in Europe and in the world, to systematically apply Mendel's laws to plant breeding, particularly to wheat breeding which resulted in varieties characterized by rust resistance, early flowering and maturity and short straw. Due to Strampelli's varieties Italian wheat production doubled, an achievement that during the fascist regime was referred to as the ‘Wheat Battle’.Some of Strampelli's wheats, such as Mentana, Ardito and San Pastore, were used as parents in the breeding programmes of several countries after the Second World War; they also had a key role in the first phase of Norman Borlaug's Green Revolution, being instrumental in the development of the high-yielding varieties of the future Nobel Peace Laureate.A century after the key cross in which Strampelli, 30 years before Borlaug, used the genes for short straw and earliness in wheat breeding, his name and his work are not known and appreciated as they deserve, despite the recent evidence that the resistance to the new rust races could derive from the very same resistance genes identified by the Italian breeder at the beginning of the 20th century.

This chapter illustrates the contribution that landraces and the wild progenitor of cultivated barley, Hordeum spontaneum, can make to increase agricultural production, particularly in areas with severe climatic and nutritional stresses such as the Syrian steppe.