Wild barley is adapted to highly diverse environments throughout its geographical distribution range. Transcriptome sequencing of differentially adapted wild barley ecotypes from contrasting environments contributes to the identification of genes and genetic variation involved in abiotic stress tolerance and adaptation. Two differentially adapted wild barley ecotypes from desert (B1K2) and Mediterranean (B1K30) environments were analyzed for drought stress response under controlled conditions. The desert ecotype lost more water under both irrigation and drought, but exhibited higher relative water content (RWC) and better water use efficiency (WUE) than the coastal ecotype. We sequenced normalized cDNA libraries from drought-stressed leaves of both ecotypes with the 454 platform to identify drought-related transcripts. Over half million reads per ecotype were de novo assembled into 20,439 putative unique transcripts (PUTs) for B1K2, 21,494 for B1K30 and 28,720 for the joint assembly. Over 50% of PUTs of each ecotype were not shared with the other ecotype. Furthermore, 16% (3,245) of B1K2 and 17% (3,674) of B1K30 transcripts did not show orthologous sequence hits in the other wild barley ecotype and cultivated barley, and are candidates of ecotype-specific transcripts. Over 800 unique transcripts from each ecotype homologous to over 30 different stress-related genes were identified. We extracted 1,017 high quality SNPs that differentiated the two ecotypes. The genetic distance between the desert ecotype and cultivated barley was 1.9-fold higher than between the Mediterranean ecotype and cultivated barley. Moreover, the desert ecotype harbored a larger proportion of non-synonymous SNPs than the Mediterranean ecotype suggesting different demographic histories of these ecotypes. The results indicate a strong physiological and genomic differentiation between the desert and Mediterranean wild barley ecotypes and a closer relationship of the Mediterranean to cultivated barley. A significant number of novel transcripts specific to wild barley were identified. The higher SNP density and larger proportion of SNPs with functional effects in the desert ecotype suggest different demographic histories and effects of natural selection in Mediterranean and desert wild barley. The data are a valuable genomic resource for an improved genome annotation, transcriptome studies of drought adaptation and a source of new genetic markers for future barley improvement.

A network of 21 experiments was established across nine countries on four continents and spanning both hemispheres, to evaluate the relative performance of early generation perennial cereal material derived from wheat, rye, and barley and to inform future breeding strategies. The experimental lines were grown in replicated single rows, and first year production and phenology characteristics as well as yield and persistence for up to three years were monitored. The study showed that the existing experimental material is all relatively short-lived (≤3 years), with environments that are milder in summer and winter generally conferring greater longevity. No pedigree was superior across this diverse network of sites although better performing lines at the higher latitude sites were generally derived from Thinopyrum intermedium. By contrast, at lower latitudes the superior lines were generally derived from Th. ponticum and Th. elongatum parentage. The study observed a poor relationship between year 1 performance and productivity in later years, highlighting the need for perennial cereal material with greater longevity to underpin future experimental evaluation, and the importance for breeding programs to emphasize post-year 1 performance in their selections. Hybrid lines derived from the tetraploid durum wheat generally showed greater longevity than derivatives of hexaploid wheat, highlighting potential for greater use of Triticum turgidum in perennial wheat breeding. We advocate a model in future breeding initiatives that develops perennial cereal genotypes for specific target environments rather than a generic product for one global market. These products may include a diversity of cultivars derived from locally adapted annual and perennial parents. In this scenario the breeding program may have access to only a limited range of adapted perennial grass parents. In other situations, such as at very high latitude environments, perennial crops derived from barley or rye may have a better chance of success than those derived from wheat. In either case, development and selection of the perennial parent for adaptation to local environments would seem fundamental to success.

We investigated the variation in plant response in host-pathogen interactions between wild (Aegilops spp., Triticum spp.) and domesticated wheat (Triticum spp.) and Wheat dwarf virus (WDV). The distribution of WDV and its wild host species overlaps in Western Asia in the Fertile Crescent, suggesting a coevolutionary relationship. Bread wheat originates from a natural hybridization between wild emmer wheat (carrying the A and B genomes) and the wild D genome donor Aegilops tauschii, followed by polyploidization and domestication. We studied whether the strong selection during these evolutionary processes, leading to genetic bottlenecks, may have resulted in a loss of resistance in domesticated wheat. In addition, we investigated whether putative fluctuations in intensity of selection imposed on the host-pathogen interactions have resulted in a variation in susceptibility to WDV. To test our hypotheses we evaluated eighteen wild and domesticated wheat taxa, directly or indirectly involved in wheat evolution, for traits associated with WDV disease such as leaf chlorosis, different growth traits and WDV content. The plants were exposed to viruliferous leafhoppers (Psammotettix alienus) in a greenhouse trial and evaluated at two time points. We found three different plant response patterns: i) continuous reduction in growth over time, ii) weak response at an early stage of plant development but a much stronger response at a later stage, and iii) remission of symptoms over time. Variation in susceptibility may be explained by differences in the intensity of natural selection, shaping the coevolutionary interaction between WDV and the wild relatives. However, genetic bottlenecks during wheat evolution have not had a strong impact on WDV resistance. Further, this study indicates that the variation in susceptibility may be associated with the genome type and that the ancestor Ae. tauschii may be useful as genetic resource for the improvement of WDV resistance in wheat.

Perennial grains have potential to contribute to ecological intensification of food production by enabling the direct harvest of human-edible crops without requiring annual cycles of disturbance and replanting. Studies of prototype perennial grains and other herbaceous perennials point to the ability of agroecosystems including these crops to protect water quality, enhance wildlife habitat, build soil quality, and sequester soil carbon. However, genetic improvement of perennial grain candidates has been hindered by limited investment due to uncertainty about whether the approach is viable. As efforts to develop perennial grain crops have expanded in past decades, critiques of the approach have arisen. With a recent report of perennial rice producing yields equivalent to those of annual rice over eight consecutive harvests, many theoretical concerns have been alleviated. Some valid questions remain over the timeline for new crop development, but we argue these may be mitigated by implementation of recent technological advances in crop breeding and genetics such as low-cost genotyping, genomic selection, and genome editing. With aggressive research investment in the development of new perennial grain crops, they can be developed and deployed to provide atmospheric greenhouse gas reductions.

Perennial cereal crops could limit the negative impacts of agriculture on the environment and climate change. In cold temperate climates, perennial plants must be adapted to seasonal changes and abiotic stresses, such as frost, to be able to regrow for several years. Wild crop relatives that are perennials and already adapted to cold temperate climates may provide genetic resources for breeding new perennial cereal grain crops. Barley (Hordeum vulgare) is one of the most important cereals in northern agricultural areas, and its related perennial species may be good candidates for the development of perennial cereals. We evaluated a diverse set of 17 wild perennial Hordeum species represented by 67 accessions in field conditions with a cold winter climate and long days during summer in Central Sweden (latitude 60° N). Six species (H. brevisubulatum, H. bulbosum, H. fuegianum, H. jubatum, H. lechleri and H. secalinum) showed regrowth and formation of spikes for four seasons. The most distant perennial relative of barley, H. stenostachys, showed weak regrowth. H. bulbosum, the closest perennial barley relative, had a large number of accessions with wide geographic origins that showed good regrowth. Together with its storage bulbs and its cross-compatibility with barley, this makes H. bulbosum an important genetic resource for the development of perennial Hordeum grains using either the domestication or the wide-hybridization strategy.

Albinism is a major limitation in the production of doubled haploid plants in cereals. As this trait is partly genetically controlled, the culture method has to be adapted to the plant genotype to reduce albinism. We have improved green plant recovery in the Northern barley (Hordeum vulgare L.) spring cultivar Mitja from 6 to 42% by altering the culture method and composition of the culture media. In a new three‐step protocol, the addition of casein hydrolysate to an intermediate regeneration medium gave the highest number of green plants. The shoot and root growth medium used for germinated embryos was superior to the standard media reported in the literature for root formation and shoot growth. Our modified method has merit for testing with other recalcitrant genotypes in anther and isolated microspore cultures.