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Abstract Barley is one of the founder crops of the Neolithic transition in West Asia. While recent advances in genomics have provided a rather detailed picture of barley domestication, there are contradictory views on how the domestication process affected genetic diversity. We set out to revisit this question by integrating public DNA sequencing data from ancient barley and wide collections of extant wild and domesticated accessions. Using two previously overlooked approaches – analyses of chloroplast genomes and genome‐wide proportions of private variants – we found that the barley cultivated six millennia ago was genetically unique and more diverse when compared to extant landraces and cultivars. Moreover, the chloroplast genomes revealed a link between the ancient barley, an obscure wild genotype from north‐eastern Libya, and a distinct population of barley cultivated in Ethiopia/Eritrea. Based on these results, we hypothesize past existence of a wider North African population that included both wild and cultivated types and suffered from genetic erosion in the past six millennia, likely due to a rapid desertification that ended the Holocene African humid period. Besides providing clues about the origin of Ethiopian landraces, the hypothesis explains the post‐domestication loss of diversity observed in barley. Analyses of additional samples will be necessary to resolve the history of African barley and its contribution to the extant cultivated gene pool.

Alfalfa (Medicago sativa L.) is a vitally important perennial fodder legume worldwide. Given their particular traits, alfalfa crop wild relatives (CWRs) could be used to develop cultivars that can tolerate extreme environmental and climatic conditions. Until now, researchers have overlooked the composition and structure of bacterial communities in the root zone of alfalfa and its relevant CWRs and their influence on forage performance under actual field conditions. In this study, high-throughput sequencing of 16S rRNA analysis was performed to investigate the diversity and assemblies of bacterial communities in the bulk soil and in the root zone of individual field-grown Medicago plants arranged in a honeycomb selection design. The plants used in this study were M. sativa × M. arborea hybrids (Genotypes 6 and 8), the closely-related M. sativa nothosubsp. varia (Martyn) Arcang. (Genotype 13), and M. sativa ssp. sativa (Genotype 20). The bacterial communities in the root-zone samples and the assemblies in the bulk soil differed significantly. Genotype 13 was found to have distinct bacterial assemblies from the other genotypes while exhibiting the lowest forage productivity. These findings suggest that plant productivity may influence the composition of bacterial communities in the root zone. Biomarker analysis conducted using linear discriminant analysis (LDA) revealed that only members of the Rhizobiales order were enriched in the M. sativa nothosubsp. varia root zone whereas taxa belonging to Sphingomonas and various Bacteriodota were enriched in the other genotypes. Of the shared taxa identified in the root zone of the Medicago lines, the abundance of specific taxa, namely, Flavisolibacter, Stenotrophomonas, and Sphingomonas, were positively associated with forage yield. This pioneering study, in which the root zones of individual Medicago plants under actual field conditions were examined, offers evidence of differences in the bacterial composition of alfalfa genotypes with varying genetic backgrounds. Its findings indicate that particular bacterial taxa may favorably influence plant performance. This study covered the first six months of crop establishment and paves the way for further investigations to advance understanding of how shifts in bacterial assemblies in alfalfa roots affect plant performance over time.

Abstract De novo domestication—the modification of domestication genes in crop wild relatives via genome editing—is an approach for harnessing the beneficial genetic diversity of crop wild relatives. A prerequisite for de novo domestication is phenotyping to identify genetic materials suitable for cultivation in the respective environment. Taxa from the wheat genepool (Triticum aestivum, Triticum durum, Triticum monococcum) are a staple food; these taxa comprise wild relatives of different ploidy levels. The diploid Triticum boeoticum and Triticum urartu and the tetraploid Triticum dicoccoides and Triticum araraticum harbor desirable traits such as high grain quality and abiotic and biotic stress tolerance. Hence, they are candidates for de novo domestication. Here, we grew 111 wild wheats and 38 landraces originating predominantly from the Fertile Crescent and six modern wheat cultivars in a field in Giessen, Germany, to evaluate their environmental adaptability to the central European climate and to identify potential candidates and target traits for de novo domestication. We demonstrate that several wild taxa are suitable for cultivation in the central European environment and that they have distinct characteristics that need to be modified during de novo domestication. The normalized difference vegetation index and the thermal time to heading and flowering indicated excellent adaptability of some wheat wild relatives to central European conditions. The values of yield parameters such as grain weight per plant, number of tillers, and thousand kernel weight were lower in the wild wheats than in the landraces. Therefore, these traits should be targeted for improvement during the de novo domestication of wild wheats.

Abstract Grass pea (Lathyrus sativus L.) is a rich source of protein cultivated as an insurance crop in Ethiopia, Eritrea, India, Bangladesh, and Nepal. Its resilience to both drought and flooding makes it a promising crop for ensuring food security in a changing climate. The lack of genetic resources and the crop’s association with the disease neurolathyrism have limited the cultivation of grass pea. Here, we present an annotated, long read-based assembly of the 6.5 Gbp L. sativus genome. Using this genome sequence, we have elucidated the biosynthetic pathway leading to the formation of the neurotoxin, β-L-oxalyl-2,3-diaminopropionic acid (β-L-ODAP). The final reaction of the pathway depends on an interaction between L. sativus acyl-activating enzyme 3 (LsAAE3) and a BAHD-acyltransferase (LsBOS) that form a metabolon activated by CoA to produce β-L-ODAP. This provides valuable insight into the best approaches for developing varieties which produce substantially less toxin.

Recently, entire genebank collections of wheat have been extensively characterized with sequencing data. We have identified introgressions using these genotyping-by-sequencing and whole-genome sequencing data. On the basis of our results, we provide information about predicted introgressions at 1-Mb resolution for 9,172 wheat samples as a resource for breeders and scientists. We recommend that all plant genetic resources, including genebank collections, be characterized using a combination of variant calling and introgression prediction. This is necessary to identify potential duplicates in collections efficiently and reliably, and to select promising germplasms with potentially beneficial introgressions for further characterization and prospective breeding application.

Abstract Introgressions from crop wild relatives (CWRs) have been used to introduce beneficial traits into cultivated plants. Introgressions have traditionally been detected using cytological methods. Recently, single nucleotide polymorphism (SNP)-based methods have been proposed to detect introgressions in crosses for which both parents are known. However, for unknown material, no method was available to detect introgressions and predict the putative donor species. Here, we present a method to detect introgressions and the putative donor species. We demonstrate the utility of this method using 10 publicly available wheat genome sequences and identify nine major introgressions. We show that the method can distinguish different introgressions at the same locus. We trace introgressions to early wheat cultivars and show that natural introgressions were utilised in early breeding history and still influence elite lines today. Finally, we provide evidence that these introgressions harbour resistance genes.

Recent technological advances in next-generation sequencing (NGS) technologies have dramatically reduced the cost of DNA sequencing, allowing species with large and complex genomes to be sequenced. Although bread wheat (Triticum aestivum L.) is one of the world’s most important food crops, efficient exploitation of molecular marker-assisted breeding approaches has lagged behind that achieved in other crop species, due to its large polyploid genome. However, an international public–private effort spanning 9 years reported over 65% draft genome of bread wheat in 2014, and finally, after more than a decade culminated in the release of a gold-standard, fully annotated reference wheat-genome assembly in 2018. Shortly thereafter, in 2020, the genome of assemblies of additional 15 global wheat accessions was released. As a result, wheat has now entered into the pan-genomic era, where basic resources can be efficiently exploited. Wheat genotyping with a few hundred markers has been replaced by genotyping arrays, capable of characterizing hundreds of wheat lines, using thousands of markers, providing fast, relatively inexpensive, and reliable data for exploitation in wheat breeding. These advances have opened up new opportunities for marker-assisted selection (MAS) and genomic selection (GS) in wheat. Herein, we review the advances and perspectives in wheat genetics and genomics, with a focus on key traits, including grain yield, yield-related traits, end-use quality, and resistance to biotic and abiotic stresses. We also focus on reported candidate genes cloned and linked to traits of interest. Furthermore, we report on the improvement in the aforementioned quantitative traits, through the use of (i) clustered regularly interspaced short-palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9)-mediated gene-editing and (ii) positional cloning methods, and of genomic selection. Finally, we examine the utilization of genomics for the next-generation wheat breeding, providing a practical example of using in silico bioinformatics tools that are based on the wheat reference-genome sequence.

Genebanks hold comprehensive collections of wild species, wild relatives, and landraces that are useful for genetic improvement. Here, the authors report the genotype of nearly 80,000 wheat accessions using DArTseq technology to show the less explored genetic diversity.

Wheat occupies a special role in global food security since, in addition to providing 20% of our carbohydrates and protein, almost 25% of the global production is traded internationally. The importance of wheat for food security was recognised by the Chief Agricultural Scientists of the G20 group of countries when they endorsed the establishment of the Wheat Initiative in 2011. The Wheat Initiative was tasked with supporting the wheat research community by facilitating collaboration, information and resource sharing and helping to build the capacity to address challenges facing production in an increasingly variable environment. Many countries invest in wheat research. Innovations in wheat breeding and agronomy have delivered enormous gains over the past few decades, with the average global yield increasing from just over 1 tonne per hectare in the early 1960s to around 3.5 tonnes in the past decade. These gains are threatened by climate change, the rapidly rising financial and environmental costs of fertilizer, and pesticides, combined with declines in water availability for irrigation in many regions. The international wheat research community has worked to identify major opportunities to help ensure that global wheat production can meet demand. The outcomes of these discussions are presented in this paper.

Abstract Background Adaptation to drought-prone environments requires robust root architecture. Genotypes with a more vigorous root system have the potential to better adapt to soils with limited moisture content. However, root architecture is complex at both, phenotypic and genetic level. Customized mapping panels in combination with efficient screenings methods can resolve the underlying genetic factors of root traits. Results A mapping panel of 233 spring barley genotypes was evaluated for root and shoot architecture traits under non-stress and osmotic stress. A genome-wide association study elucidated 65 involved genomic regions. Among them were 34 root-specific loci, eleven hotspots with associations to up to eight traits and twelve stress-specific loci. A list of candidate genes was established based on educated guess. Selected genes were tested for associated polymorphisms. By this, 14 genes were identified as promising candidates, ten remained suggestive and 15 were rejected. The data support the important role of flowering time genes, including HvPpd-H1, HvCry2, HvCO4 and HvPRR73. Moreover, seven root-related genes, HERK2, HvARF04, HvEXPB1, PIN5, PIN7, PME5 and WOX5 are confirmed as promising candidates. For the QTL with the highest allelic effect for root thickness and plant biomass a homologue of the Arabidopsis Trx-m3 was revealed as the most promising candidate. Conclusions This study provides a catalogue of hotspots for seedling growth, root and stress-specific genomic regions along with candidate genes for future potential incorporation in breeding attempts for enhanced yield potential, particularly in drought-prone environments. Root architecture is under polygenic control. The co-localization of well-known major genes for barley development and flowering time with QTL hotspots highlights their importance for seedling growth. Association analysis revealed the involvement of HvPpd-H1 in the development of the root system. The co-localization of root QTL with HERK2, HvARF04, HvEXPB1, PIN5, PIN7, PME5 and WOX5 represents a starting point to explore the roles of these genes in barley. Accordingly, the genes HvHOX2, HsfA2b, HvHAK2, and Dhn9, known to be involved in abiotic stress response, were located within stress-specific QTL regions and await future validation.

Abstract Background Seeds of domesticated barley are grouped into two distinct types, which differ in morphology. Caryopses covered by adaxial (palea) and abaxial (lemma) hulls that tightly adhere to the pericarp at maturity give rise to hulled seeds whereas caryopses without adhering hulls give rise to naked seeds. The naked caryopsis character is an essential trait regarding the end use of barley. Results To uncover the genetic basis of the trait, a genome-wide association study (GWAS) has been performed in a panel comprising 222 2-rowed and 303 6-rowed spring barley landrace accessions. In addition to the well-described Nud locus on chromosome 7H, three novel loci showed strong associations with the trait: the first locus on 2H was specifically detected in 6-rowed accessions, the second locus on 3H was found in 2-rowed accessions from Eurasia and the third locus on 6H was revealed in 6-rowed accessions from Ethiopia. PCR analysis of naked accessions also confirmed the absence of a 17 kb region harboring the Nud gene on chromosome 7H for all but one naked accession. The latter was characterized by a slightly variant phenotype of the caryopsis. Conclusion Our findings provide evidence of the pervasiveness of the 17 kb deletion in spring barley from different geographic regions and at the same time reveal genomic footprints of selection in naked barley, which follow both geographic and morphological patterns.

The Adapting Agriculture to Climate Change Project set out to improve the diversity, quantity, and accessibility of germplasm collections of crop wild relatives (CWR). Between 2013 and 2018, partners in 25 countries, heirs to the globetrotting legacy of Nikolai Vavilov, undertook seed collecting expeditions targeting CWR of 28 crops of global significance for agriculture. Here, we describe the implementation of the 25 national collecting programs and present the key results. A total of 4587 unique seed samples from at least 355 CWR taxa were collected, conserved ex situ, safety duplicated in national and international genebanks, and made available through the Multilateral System (MLS) of the International Treaty on Plant Genetic Resources for Food and Agriculture (Plant Treaty). Collections of CWR were made for all 28 targeted crops. Potato and eggplant were the most collected genepools, although the greatest number of primary genepool collections were made for rice. Overall, alfalfa, Bambara groundnut, grass pea and wheat were the genepools for which targets were best achieved. Several of the newly collected samples have already been used in pre-breeding programs to adapt crops to future challenges.

Pigeonpea is a photoperiod-sensitive crop; therefore, the introgression of photoperiod insensitivity could increase its adaptability to new environments. We determined the effect of extended daylength (ED; 16 h light) on the phenotypical traits of extra-early, early, and mid-early maturing pigeonpea introgression lines (ILs) derived from wild Cajanus species belonging to secondary and tertiary gene pools. Plants were grown under natural daylength and extended daylength in a greenhouse. Comparisons of the time of floral bud initiation, days to flowering, plant height, number of branches, and number of leaf nodes on the main stem at flowering revealed photoperiod-insensitive lines. All traits varied widely among the ILs. Analyses of flowering traits revealed large genetic components with low genotype × treatment interactions and high broad-sense heritability. The photoperiod most strongly affected the number of primary branches, followed by plant height. The extended day advanced flowering by approximately four days in extra-early ILs, confirming that these ILs are quantitative, short-day plants. The photoperiod insensitivity index varied from 0.88 in ICPP 171541 (moderately photoperiod sensitive) to 0.99 in ICPP 171546 and ICPP 171561 (photoperiod insensitive). These photoperiod-insensitive extra-early flowering ILs can be used to enrich the genetic diversity of pigeonpea and to develop photoperiod-insensitive cultivars for cultivation in new environments.

Pod borer (Helicoverpa armigera) causes the highest yield losses in pigeonpea, followed by pod fly (Melanagromyza obtusa). High levels of resistance to pod borer are not available in the cultivated genepool. Several accessions of wild Cajanus species with strong resistance, and different resistance mechanisms (antixenosis and antibiosis) to pod borer have been identified. These accessions can be utilized to improve the pod borer resistance of cultivated pigeonpea. Using pod borer resistant Cajanus scarabaeoides and Cajanus acutifolius as pollen donors and popular pigeonpea varieties as recipients, pre-breeding populations were developed following simple- and complex-cross approaches. Preliminary evaluation of four backcross populations consisting of >2300 introgression lines (ILs) under un-sprayed field conditions resulted in identifying 156 ILs with low visual damage rating scores (5.0–6.0) and low pod borer damage (Cajanus species, they may contain different alleles for different resistance components to pod borer. Hence, these ILs are ready-to-use novel and diverse sources of pod borer resistance that can be utilized for improving the pod borer resistance of cultivated pigeonpea.

Enhanced levels of antioxidants, phenolic compounds, carotenoids and vitamin C have been reported for several crops grown under organic fertilizer, albeit with yield penalties. As organic agricultural practices continue to grow and find favor it is critical to gain an understanding of the molecular underpinnings of the factors that limit the yields in organically farmed crops. Concomitant phytochemical and transcriptomic analysis was performed on mature fruit and leaf tissues derived from Solanum lycopersicum L. 'Oregon Spring' grown under organic and conventional fertilizer conditions to evaluate the following hypotheses. 1. Organic soil fertilizer management results in greater allocation of photosynthetically derived resources to the synthesis of secondary metabolites than to plant growth, and 2. Genes involved in changes in the accumulation of phytonutrients under organic fertilizer regime will exhibit differential expression, and that the growth under different fertilizer treatments will elicit a differential response from the tomato genome. Both these hypotheses were supported, suggesting an adjustment of the metabolic and genomic activity of the plant in response to different fertilizers. Organic fertilizer treatment showed an activation of photoinhibitory processes through differential activation of nitrogen transport and assimilation genes resulting in higher accumulation of phytonutrients. This information can be used to identify alleles for breeding crops that allow for efficient utilization of organic inputs.

Barley is one of the oldest domesticated crops in the world and is mainly used for feed and malt and to a lesser extent as food. The use of barley as food is a tradition in communities in some countries of North Africa, Europe, and Asia. However, due to the health-promoting properties of barley grain, there is an increasing interest in such use. The International Center for Agricultural Research in the Dry Areas (ICARDA) has a global mandate for barley improvement and holds rich in-trust collections of cultivated and wild Hordeum species. The present study aims to evaluate 117 accessions of Hordeum spontaneum for their contents of β-glucan and microelements for breeding new varieties with enhanced nutritional value. The bulked seed accessions of Hordeum spontaneum were grown over two seasons, and the single plant derived seeds from these accessions were compared to 36 elite lines and varieties of cultivated barley in the second season in Morocco. The results showed large differences in β-glucan and microelements in both the bulk and the single plant seed accessions. The contents of β-glucans ranged from 1.44 to 11.3% in the Hordeum spontaneum accessions and from 1.62 to 7.81% in the cultivated barley lines. Large variations were found for the microelements content, but no differences were noticed between the wild and the cultivated species. However, some accessions of Hordeum spontaneum had higher combined contents of Iron, Zinc, and Selenium. Such accessions are used in interspecific crosses to develop biofortified barley germplasm and varieties.

Wheat (Triticum sp.) is one of the world’s most important crops, and constantly increasing its productivity is crucial to the livelihoods of millions of people. However, more than a century of intensive breeding and selection processes have eroded genetic diversity in the elite genepool, making new genetic gains difficult. Therefore, the need to introduce novel genetic diversity into modern wheat has become increasingly important. This review provides an overview of the plant genetic resources (PGR) available for wheat. We describe the most important taxonomic and phylogenetic relationships of these PGR to guide their use in wheat breeding. In addition, we present the status of the use of some of these resources in wheat breeding programs. We propose several introgression schemes that allow the transfer of qualitative and quantitative alleles from PGR into elite germplasm. With this in mind, we propose the use of a stage-gate approach to align the pre-breeding with main breeding programs to meet the needs of breeders, farmers, and end-users. Overall, this review provides a clear starting point to guide the introgression of useful alleles over the next decade.

Cowpea [Vigna unguiculata (L.) Walp.] is a major legume crop and an important source of protein in Africa. The Kafr El-Sheikh University has a long history of cowpea breeding and improvement in Egypt. Two superior lines with high seed yield and quality were selected through mutation breeding and released to farmers as new varieties under the names Kafr El Sheikh-1 and Kaha-1. Crosses were made between these two varieties to further improve cowpea to meet farmers’ demand. Using the pedigree selection method, 13 new superior F10 lines were selected and evaluated over 2 years for seed yield and related traits, earliness, and protein content under low (16 plants/m2) and high (24 plants/m2) plant densities. The results showed that plants grown in narrower space produced significantly higher seed yield per unit area than the plants grown in wider space. All developed lines produced significantly higher seed yield than the two parental lines in the 2018 trial and Kaha-1 in the 2019 trial. Line number 6 proved to be the best genotype for earliness (73.5–73.9 days after sowing), seed yield (573–647 g/m2), and crude protein content (22.7–24.3%) in both trials. In addition, line 4 with bushy determinate growth habit and high seed quality was recently released as a new variety (Sakha-1). Several other cowpea lines have clear potential for release as new high-yielding varieties with early maturity and high seed quality for farmers in Egypt. Seeds of selected lines are available from Kafrelsheikh University. This shows that mutation breeding and pedigree selection methods are among the most promising breeding methods for cowpea improvement.

The harvesting of sweet cherry (Prunus avium L.) fruit is a labor-intensive process. The mechanical harvesting of sweet cherry fruit is feasible; however, it is dependent on the formation of an abscission zone at the fruit–pedicel junction. The natural propensity for pedicel-–fruit abscission zone (PFAZ) activation varies by cultivar, and the general molecular basis for PFAZ activation is not well characterized. In this study, ethylene-inducible change in pedicel fruit retention force (PFRF) was recorded in a developmental time-course with a concomitant analysis of the PFAZ transcriptome from three sweet cherry cultivars. In ‘Skeena’, mean PFRF for both control and treatment fruit dropped below the 0.40 kg-force (3.92 N) threshold for mechanical harvesting, indicating the activation of a discrete PFAZ. In ‘Bing’, mean PFRF for both control and treatment groups decreased over time. However, a mean PFRF conducive to mechanical harvesting was achieved only in the ethylene-treated fruit. While in ‘Chelan’ the mean PFRF of the control and treatment groups did not meet the threshold required for efficient mechanical harvesting. Transcriptome analysis of the PFAZ region followed by the functional annotation, differential expression analysis, and gene ontology (GO) enrichment analyses of the data facilitated the identification of phytohormone-responsive and abscission-related transcripts, as well as processes that exhibited differential expression and enrichment in a cultivar-dependent manner over the developmental time-course. Additionally, read alignment-based variant calling revealed several short variants in differentially expressed genes, associated with enriched gene ontologies and associated metabolic processes, lending potential insight into the genetic basis for different abscission responses between the cultivars. These results provide genetic targets for the induction or inhibition of PFAZ activation, depending on the desire to harvest the fruit with or without the stem attached. Understanding the genetic mechanisms underlying the development of the PFAZ will inform future cultivar development while laying a foundation for mechanized sweet cherry harvest.

Abstract Background Genetic mapping of phenotypic traits generally focuses on a single time point, but biomass accumulates continuously during plant development. Resolution of the temporal dynamics that affect biomass recently became feasible using non-destructive imaging. Results With the aim to identify key genetic factors for vegetative biomass formation from the seedling stage to flowering, we explored growth over time in a diverse collection of two-rowed spring barley accessions. High heritabilities facilitated the temporal analysis of trait relationships and identification of quantitative trait loci (QTL). Biomass QTL tended to persist only a short period during early growth. More persistent QTL were detected around the booting stage. We identified seven major biomass QTL, which together explain 55% of the genetic variance at the seedling stage, and 43% at the booting stage. Three biomass QTL co-located with genes or QTL involved in phenology. The most important locus for biomass was independent from phenology and is located on chromosome 7HL at 141 cM. This locus explained ~20% of the genetic variance, was significant over a long period of time and co-located with HvDIM, a gene involved in brassinosteroid synthesis. Conclusions Biomass is a dynamic trait and is therefore orchestrated by different QTL during early and late growth stages. Marker-assisted selection for high biomass at booting stage is most effective by also including favorable alleles from seedling biomass QTL. Selection for dynamic QTL may enhance genetic gain for complex traits such as biomass or, in the future, even grain yield.

Abstract Background Triticeae, the tribe of wheat grasses, harbours the cereals barley, rye and wheat and their wild relatives. Although economically important, relationships within the tribe are still not understood. We analysed the phylogeny of chloroplast lineages among nearly all monogenomic Triticeae taxa and polyploid wheat species aiming at a deeper understanding of the tribe’s evolution. We used on- and off-target reads of a target-enrichment experiment followed by Illumina sequencing. Results The read data was used to assemble the plastid locus ndhF for 194 individuals and the whole chloroplast genome for 183 individuals, representing 53 Triticeae species and 15 genera. We conducted Bayesian and multispecies coalescent analyses to infer relationships and estimate divergence times of the taxa. We present the most comprehensive dated Triticeae chloroplast phylogeny and review previous hypotheses in the framework of our results. Monophyly of Triticeae chloroplasts could not be confirmed, as either Bromus or Psathyrostachys captured a chloroplast from a lineage closely related to a Bromus-Triticeae ancestor. The most recent common ancestor of Triticeae occurred approximately between ten and 19 million years ago. Conclusions The comparison of the chloroplast phylogeny with available nuclear data in several cases revealed incongruences indicating past hybridizations. Recent events of chloroplast capture were detected as individuals grouped apart from con-specific accessions in otherwise monopyhletic groups.

Identification of genetic polymorphisms and subsequent development of molecular markers is important for marker assisted breeding of superior cultivars of economically important species. Sweet cherry (Prunus avium L.) is an economically important non-climacteric tree fruit crop in the Rosaceae family and has undergone a genetic bottleneck due to breeding, resulting in limited genetic diversity in the germplasm that is utilized for breeding new cultivars. Therefore, it is critical to recognize the best platforms for identifying genome-wide polymorphisms that can help identify, and consequently preserve, the diversity in a genetically constrained species. For the identification of polymorphisms in five closely related genotypes of sweet cherry, a gel-based approach (TRAP), reduced representation sequencing (TRAPseq), a 6k cherry SNParray, and whole genome sequencing (WGS) approaches were evaluated in the identification of genome-wide polymorphisms in sweet cherry cultivars. All platforms facilitated detection of polymorphisms among the genotypes with variable efficiency. In assessing multiple SNP detection platforms, this study has demonstrated that a combination of appropriate approaches is necessary for efficient polymorphism identification, especially between closely related cultivars of a species. The information generated in this study provides a valuable resource for future genetic and genomic studies in sweet cherry, and the insights gained from the evaluation of multiple approaches can be utilized for other closely related species with limited genetic diversity in the breeding germplasm. Keywords: Polymorphisms, Prunus avium, Next-generation sequencing, Target region amplification polymorphism (TRAP), Genetic diversity, SNParray, Reduced representation sequencing, Whole genome sequencing (WGS)

With ongoing climate change, drought events are becoming more frequent and will affect biomass formation when occurring during pre-flowering stages. We explored growth over time under such a drought scenario, via non-invasive imaging and revealed the underlying key genetic factors in spring barley. By comparing with well-watered conditions investigated in an earlier study and including information on timing, QTL could be classified as constitutive, drought or recovery-adaptive. Drought-adaptive QTL were found in the vicinity of genes involved in dehydration tolerance such as dehydrins (Dhn4, Dhn7, Dhn8, and Dhn9) and aquaporins (e.g. HvPIP1;5, HvPIP2;7, and HvTIP2;1). The influence of phenology on biomass formation increased under drought. Accordingly, the main QTL during recovery was the region of HvPPD-H1. The most important constitutive QTL for late biomass was located in the vicinity of HvDIM, while the main locus for seedling biomass was the HvWAXY region. The disappearance of QTL marked the genetic architecture of tiller number. The most important constitutive QTL was located on 6HS in the region of 1-FEH. Stage and tolerance specific QTL might provide opportunities for genetic manipulation to stabilize biomass and tiller number under drought conditions and thereby also grain yield.

Markers linked to agronomic traits are of the prerequisite for molecular breeding. Genotyping-by-sequencing (GBS) data enables to detect small polymorphisms including single nucleotide polymorphisms (SNPs) and short insertions or deletions (InDels) that can be used, for instance, for marker-assisted selection, population genetics, and genome-wide association studies (GWAS). Here, we aim at detecting large chromosomal modifications in barley and wheat based on GBS data. These modifications could be duplications, deletions, substitutions including introgressions as well as alterations of DNA methylation. We demonstrate that GBS coverage analysis is capable to detect Hordeum vulgare/Hordeum bulbosum introgression lines. Furthermore, we identify large chromosomal modifications in barley and wheat collections. Hence, large chromosomal modifications, including introgressions and copy number variations (CNV), can be detected easily and can be used as markers in research and breeding without additional wet-lab experiments.

Breeding new crop cultivars with efficient root systems carries great potential to enhance resource use efficiency and plant adaptation to unstable climates. Here, we evaluated the natural variation of root system architectural traits in a diverse spring barley association panel and conducted genome-wide association mapping to identify genomic regions associated with root traits. For six studied traits, root system depth, root spreading angle, seminal root number, total seminal root length, and average seminal root length 1.9- to 4.2-fold variations were recorded. Using a mixed linear model, 55 QTLs were identified cumulatively explaining between 12.1% of the phenotypic variance for seminal root number to 48.1% of the variance for root system depth. Three major QTLs controlling root system depth, root spreading angle and total seminal root length were found on Chr 2H (56.52 cM), Chr 3H (67.92 cM), and Chr 2H (76.20 cM) and explained 12.4%, 18.4%, and 22.2% of the phenotypic variation, respectively. Meta-analysis and allele combination analysis indicated that root system depth and root spreading angle are valuable candidate traits for improving grain yield by pyramiding of favorable alleles.

Genebanks are a rich source of genetic variation. Most of this variation is absent in breeding programs but may be useful for further crop plant improvement. However, the lack of phenotypic information forms a major obstacle for the educated choice of genebank accessions for research and breeding. A promising approach to fill this information gap is to exploit historical information gathered routinely during seed regeneration cycles. Still, this data is characterized by a high non-orthogonality hampering their analysis. By examining historical data records for flowering time, plant height, and thousand grain weight collected during 70 years of regeneration of 6,207 winter wheat (Triticum aestivum L.) accessions at the German Federal ex situ Genebank, we aimed to elaborate a strategy to analyze and validate non-orthogonal historical data in order to charge genebank information platforms with high quality ready-to-use phenotypic information. First, a three-step quality control assessment considering the plausibility of trait values and a standard as well as a weather parameter index based outlier detection was implemented, resulting in heritability estimates above 0.90 for all three traits. Then, the data was analyzed by estimating best linear unbiased estimations (BLUEs) applying a linear mixed-model approach. An in silico resampling study mimicking different missing data patterns revealed that accessions should be regenerated in a random fashion and not blocked by origin or acquisition date in order to minimize estimation biases in historical data sets. Validation data was obtained from multi-environmental orthogonal field trials considering a random subsample of 3,083 accessions. Correlations above 0.84 between BLUEs estimated for historical data and validation trials outperformed previous approaches and confirmed the robustness of our strategy as well as the high quality of the historical data. The results indicate that the IPK winter wheat collection reveals an extraordinary high phenotypic diversity compared to other collections. The quality checked ready-to-use phenotypic information resulting from this study is the first brick to extend traditional, conservation driven genebanks into bio-digital resource centers.

A collection of 379 Hordeum vulgare cultivars, comprising all combinations of spring and winter growth habits with two and six row ear type, was screened by genome wide association analysis to discover alleles controlling traits related to grain yield. Genotypes were obtained at 6,810 segregating gene-based single nucleotide polymorphism (SNP) loci and corresponding field trial data were obtained for eight traits related to grain yield at four European sites in three countries over two growth years. The combined data were analyzed and statistically significant associations between the traits and regions of the barley genomes were obtained. Combining this information with the high resolution gene map for barley allowed the identification of candidate genes underlying all scored traits and superposition of this information with the known genomics of grain trait genes in rice resulted in the assignation of 13 putative barley genes controlling grain traits in European cultivated barley. Several of these genes are associated with grain traits in both winter and spring barley.

Despite the global value of barley, compared to its wild progenitor, genetic variation in this crop has been drastically reduced due to the process of domestication, selection and improvement. In the medium term, this will negatively impact both the vulnerability and yield stability of barley against biotic and abiotic stresses under climate change. Returning to the crop wild relatives (CWR) as sources of new and beneficial alleles is a clear option for enhancing the resilience of diversity and adaptation to climate change. Southeastern Anatolia constitutes an important part of the natural distribution of wild barley in the Fertile Crescent where important crops were initially domesticated. In this study, we investigated genetic diversity in a comprehensive collection of 281 geo-referenced wild barley individuals from 92 collection sites with sample sizes ranging from 1 to 9 individuals per site, collected from southeastern Anatolia and 131 domesticated genotypes from 49 different countries using 40 EST-SSR markers. A total of 375 alleles were detected across entire collection, of which 283 were carried by domesticated genotypes and 316 alleles were present in the wild gene pool. The number of unique alleles in the wild and in the domesticated gene pool was 92 and 59, respectively. The population structure at K = 3 suggested two groups of wild barley namely G1-W consisting wild barley genotypes from the western part and G1-E comprising those mostly from the eastern part of the study area, with a sharp separation from the domesticated gene pool. The geographic and climatic factors jointly showed significant effects on the distribution of wild barley. Using a Latent Factor Mixed Model, we identified four candidate loci potentially involved in adaptation of wild barley to three environmental factors: temperature seasonality, mean temperature of driest quarter, and precipitation of coldest quarter. These loci are probably the targets of genomic regions, with potential roles against abiotic stresses.

Einkorn and emmer wheat together with barley were among the first cereals domesticated by humans more than 10,000 years ago, long before durum or bread wheat originated. Domesticated einkorn wheat differs from its wild progenitor in basic morphological characters such as the grain dispersal system. This study identified the Non-brittle rachis 1 (btr1) and Non-brittle rachis 2 (btr2) in einkorn as homologous to barley. Re-sequencing of the Btr1 and Btr2 in a collection of 53 lines showed that a single non-synonymous amino acid substitution (alanine to threonine) at position 119 at btr1, is responsible for the non-brittle rachis trait in domesticated einkorn. Tracing this haplotype variation back to wild einkorn samples provides further evidence that the einkorn progenitor came from the Northern Levant. We show that the geographical origin of domesticated haplotype coincides with the non-brittle domesticated barley haplotypes, which suggest the non-brittle rachis phenotypes of einkorn and barley were fixed in same geographic area in today’s South-east Turkey.

Emmer wheat, Triticum dicoccon schrank (syn. T. dicoccum (schrank) schÜbl.), is one of the earliest domesticated crops, harboring a wide range of genetic diversity and agronomically valuable traits. The crop, however, is currently largely neglected. We provide a wealth of karyotypic information from a comprehensive collection of emmer wheat and related taxa. In addition to C-banding polymorphisms, we identified 43 variants of chromosomal rearrangements in T. dicoccon; among them 26 (60.4%) were novel. The T7A:5B translocation was most abundant in Western Europe and the Mediterranean. The plant genetic resources investigated here might become important in the future for wheat improvement. Based on cluster analysis four major karyotypic groups were discriminated within the T. dicoccon genepool, each harboring characteristic C-banding patterns and translocation spectra: the balkan, asian, european and ethiopian groups. We postulate four major diffusion routes of the crop and discuss their migration out of the Fertile Crescent considering latest archaeobotanical findings.

Global environmental change and increasing human population emphasize the urgent need for higher yielding and better adapted crop plants. One strategy to achieve this aim is to exploit the wealth of so called landraces of crop species, representing diverse traditional domesticated populations of locally adapted genotypes. In this study, we investigated a comprehensive set of 1485 spring barley landraces (Lrc1485) adapted to a wide range of climates, which were selected from one of the largest genebanks worldwide. The landraces originated from 5° to 62.5° N and 16° to 71° E. The whole collection was genotyped using 42 SSR markers to assess the genetic diversity and population structure. With an average allelic richness of 5.74 and 372 alleles, Lrc1485 harbours considerably more genetic diversity than the most polymorphic current GWAS panel for barley. Ten major clusters defined most of the population structure based on geographical origin, row type of the ear and caryopsis type - and were assigned to specific climate zones. The legacy core reference set Lrc648 established in this study will provide a long-lasting resource and a very valuable tool for the scientific community. Lrc648 is best suited for multi-environmental field testing to identify candidate genes underlying quantitative traits but also for allele mining approaches.

Using Roche/454 technology, we sequenced the chloroplast genomes of 12 Triticeae species, including bread wheat, barley and rye, as well as the diploid progenitors and relatives of bread wheat Triticum urartu, Aegilops speltoides and Ae. tauschii. Two wild tetraploid taxa, Ae. cylindrica and Ae. geniculata, were also included. Additionally, we incorporated wild Einkorn wheat Triticum boeoticum and its domesticated form T. monococcum and two Hordeum spontaneum (wild barley) genotypes. Chloroplast genomes were used for overall sequence comparison, phylogenetic analysis and dating of divergence times. We estimate that barley diverged from rye and wheat approximately 8-9 million years ago (MYA). The genome donors of hexaploid wheat diverged between 2.1-2.9 MYA, while rye diverged from Triticum aestivum approximately 3-4 MYA, more recently than previously estimated. Interestingly, the A genome taxa T. boeoticum and T. urartu were estimated to have diverged approximately 570,000 years ago. As these two have a reproductive barrier, the divergence time estimate also provides an upper limit for the time required for the formation of a species boundary between the two. Furthermore, we conclusively show that the chloroplast genome of hexaploid wheat was contributed by the B genome donor and that this unknown species diverged from Ae. speltoides about 980,000 years ago. Additionally, sequence alignments identified a translocation of a chloroplast segment to the nuclear genome which is specific to the rye/wheat lineage. We propose the presented phylogeny and divergence time estimates as a reference framework for future studies on Triticeae.

Heading time is a complex trait, and natural variation in photoperiod responses is a major factor controlling time to heading, adaptation and grain yield. In barley, previous heading time studies have been mainly conducted under field conditions to measure total days to heading. We followed a novel approach and studied the natural variation of time to heading in a world-wide spring barley collection (218 accessions), comprising of 95 photoperiod-sensitive (Ppd-H1) and 123 accessions with reduced photoperiod sensitivity (ppd-H1) to long-day (LD) through dissecting pre-anthesis development into four major stages and sub-phases. The study was conducted under greenhouse (GH) conditions (LD; 16/8 h; ∼20/∼16°C day/night). Genotyping was performed using a genome-wide high density 9K single nucleotide polymorphisms (SNPs) chip which assayed 7842 SNPs. We used the barley physical map to identify candidate genes underlying genome-wide association scans (GWAS). GWAS for pre-anthesis stages/sub-phases in each photoperiod group provided great power for partitioning genetic effects on floral initiation and heading time. In addition to major genes known to regulate heading time under field conditions, several novel QTL with medium to high effects, including new QTL having major effects on developmental stages/sub-phases were found to be associated in this study. For example, highly associated SNPs tagged the physical regions around HvCO1 (barley CONSTANS1) and BFL (BARLEY FLORICAULA/LEAFY) genes. Based upon our GWAS analysis, we propose a new genetic network model for each photoperiod group, which includes several newly identified genes, such as several HvCO-like genes, belonging to different heading time pathways in barley.

Two hundred sixteen barley ( L.) cultivars were selected to represent the diversity and history of European spring two-row barley breeding and to search for alleles controlling agronomic traits by association genetics. The germplasm was genotyped with 7864 gene-based single nucleotide polymorphism markers and corresponding field trial trait data relating to growth and straw strength were obtained at multiple European sites. Analysis of the marker data by statistical population genetics approaches revealed two important trends in the genetic diversity of European two-row spring barley, namely, i) directional selection for approximately 14% of total genetic variation of the population in the last approximately 50 yr and ii) highly uneven genomic distribution of genetic diversity. Association analysis of the phenotypic and genotypic data identified multiple loci affecting the traits investigated, some of which co-map with selected regions. Collectively, these data show that the genetic makeup of European two-row spring barley is evolving under breeder selection, with signs of extinction of diversity in some genomic regions, suggesting that “breeding the best with the best” is leading towards fixation of some breeder targets. Nevertheless, modern germplasm also retains many regions of high diversity, suggesting that site-specific genetic approaches for allele identification and crop improvement such as association genetics are likely to be successful.

Increasing the amount of bioavailable mineral elements in plant foods would help to improve the nutritional status of populations in developing countries. Legume seeds have the potential to provide many essential nutrients. It is important to have information on genetic variations among different lentil populations so that plant breeding programs can use new varieties in cross-breeding programs. The main objective of this study was to characterize the micro- and macronutrient concentrations of lentil landraces seeds collected from South-Eastern Turkey. We found impressive variation in the micro- and macroelement concentrations in 39 lentil landraces and 7 cultivars. We investigated the relationships of traits by correlation analysis and principal component analysis (PCA). The concentrations of several minerals, particularly Zn, were positively correlated with other minerals, suggesting that similar pathways or transporters control the uptake and transport of these minerals. Some genotypes had high mineral and protein content and potential to improve the nutritional value of cultivated lentil. Cross-breeding of numerous lentil landraces from Turkey with currently cultivated varieties could improve the levels of micro- and macronutrients of lentil and may contribute to the worldwide lentil quality breeding program.

Identifying intra-locus interactions underlying heterotic variation among whole-genome hybrids is a key to understanding mechanisms of heterosis and exploiting it for crop and livestock improvement. In this study, we present the development and first use of the heterotic trait locus (HTL) mapping approach to associate specific intra-locus interactions with an overdominant heterotic mode of inheritance in a diallel population using Sorghum bicolor as the model. This method combines the advantages of ample genetic diversity and the possibility of studying non-additive inheritance. Furthermore, this design enables dissecting the latter to identify specific intra-locus interactions. We identified three HTLs (3.5% of loci tested) with synergistic intra-locus effects on overdominant grain yield heterosis in 2 years of field trials. These loci account for 19.0% of the heterotic variation, including a significant interaction found between two of them. Moreover, analysis of one of these loci (hDPW4.1) in a consecutive F2 population confirmed a significant 21% increase in grain yield of heterozygous vs. homozygous plants in this locus. Notably, two of the three HTLs for grain yield are in synteny with previously reported overdominant quantitative trait loci for grain yield in maize. A mechanism for the reproductive heterosis found in this study is suggested, in which grain yield increase is achieved by releasing the compensatory tradeoffs between biomass and reproductive output, and between seed number and weight. These results highlight the power of analyzing a diverse set of inbreds and their hybrids for unraveling hitherto unknown allelic interactions mediating heterosis.