DArTseq Genotypic and Phenotypic Diversity of Barley Landraces Originating from Different Countries

Landraces are considered a key element of agrobiodiversity because of their high variability and adaptation to local environmental conditions, but at the same time, they represent a breeding potential hidden in gene banks that has not yet been fully appreciated and utilized. Here, we present a genome-wide DArTseq analysis of the diversity of 116 spring barley landraces preserved in the collection of the Polish gene bank. Genetic analysis revealed considerable variation in this collection and several distinct groups related to the landraces’ country of origin and the grain type were identified. The genetic distinctness of hulless accessions may provide a basis for pro-quality breeding aimed at functional food production. However, the variable level of accession heterogeneity can be a significant obstacle. A solution to this problem is the establishment of special collections composed of pure lines that are accessible to breeders. Regions lacking genetic diversity have also been identified on 1H and 4H chromosomes. A small region of reduced heterogeneity was also present in the hulless forms in the vicinity of the nud gene that determines the hulless grain type. However, the SNPs present in this area may also be important in selection for traits related to grain weight and size because their QTLs were found there. This may support breeding of hulless forms of spring barley which may have applications in the production of high-quality foods with health-promoting values.

Sources of Resistance to Powdery Mildew in Barley Landraces from Turkey

Powdery mildew on barley, caused by the pathogen Blumeria graminis f. sp. hordei, occurs worldwide and can result in severe yield loss. Germplasm of barley, including landraces, commercial cultivars, wild relatives and breeding lines are stored in more than 200 institutions. There is a need for characterization of this germplasm in terms of resistance to biotic and abiotic stresses. This is necessary in order to use specific accessions in breeding programs. In the present study, 129 barley landraces originated from Turkey and provided by the ICARDA genebank were tested for resistance to powdery mildew. Seedling resistance tests after inoculation with 19 differentiated isolates of B. graminis f. sp. hordei were used to postulate the presence of resistance genes. From the 129 landraces studied, plants of 19 (14.7%) of them showed resistance to infection with powdery mildew. Based on preliminary tests from these 19 landraces, 25 resistant single plant lines were selected for testing with differential powdery mildew isolates. Seven lines were resistant to all 19 isolates used. However, only one line (5583-1-4) showed resistance scores of zero against all isolates used. It is likely that this line possesses unknown, but highly effective genes for resistance. In five resistant lines it was not possible to postulate the presence of specific resistance genes. In 19 lines the presence of the genes Mlp, Mlk, Mlh, Mlg, Ml(CP), Mlat, Mla3, Mla6, Mla7 and Mla22 were postulated. These new sources of highly effective powdery mildew resistance in barley landraces from Turkey could be successfully used in breeding programs.

Greenbug resistance in barley landraces from Uzbekistan

Background. The greenbug (Sсhizaphis graminum Rondani) can significantly reduce the yield of barley and other cereals in the southern regions of Russia. Cultivation of resistant varieties can significantly limit the pathogen’s harmfulness. At the same time, specific interaction with the genotypes of the host plant, characteristic of S. graminum, requires a continuous search for new resistance donors to broaden the genetic diversity of barley cultivars. Materials and methods. The resistance of 178 accessions of barley landraces from Uzbekistan to the Krasnodar greenbug population was tested in laboratory experiments. Juvenile plants were infested with aphids of different ages, and when the susceptible control died (cv. ‘Belogorsky’), resistance was assessed on a 0 to 10 (plant death) rating scale. Plants with a damage rate of 1–4 points (up to 30% of the leaf surface being damaged) belonged to the resistant class; damage rate of 5–8 points indicated moderate resistance of plants, and that of 9–10 meant susceptibility. In addition, we assessed the aphid damage of the winter barley cultivar ‘Post’, protected by the previously identified resistance gene Rsg1.Results and conclusions. We identified 52 barley accessions as heterogeneous for the studied trait. In six accessions, plants with high (points 3 to 4) and moderate (5 to 8) resistance were identified; 6 accessions were differentiated into 3 phenotypic classes: resistant, moderately resistant, and susceptible; and in 40 accessions the manifestation of the resistance component varied within 5 to 7 points (from 31 to 60% of the leaf surface being damaged). The distinctly expressed resistance of 12 accessions is controlled by alleles of resistance genes that differ from Rsg1. After selection for resistance, the identified accessions can be used in breeding.

Mlo Resistance to Powdery Mildew (Blumeria graminis f. sp. hordei) in Barley Landraces Collected in Yemen

Barley (Hordeumvulgare L.) is one of the most important cereal crops in the world. Powdery mildew on barley, which is caused by the pathogen Blumeria graminis f. sp. hordei, occurs world-wide and can result in severe yield loss. Thousands of barley accessions are stored in national gene banks, and their characterization for breeding purposes is needed. This study was conducted to determine the resistance to powdery mildew in 33 barley landraces from Yemen, which were obtained from the ICARDA gene bank. Twenty differential isolates of barley powdery mildew were used. Nine single plant lines were selected from five landraces, based on tests that were performed with 30 plants per landrace, after inoculation with the most avirulent isolate of barley powdery mildew available. Two of these landraces originated from the Al Bayda province in Yemen, and three others originated from Dhamar, Sanaa, and Taizz, respectively. Next, single plant lines were tested using a set of 20 differential isolates of powdery mildew. Two lines that were selected from landrace from the Al Bayda province in Yemen, showed disease reaction designated as 0(4), which is specific for the presence of Mlo resistance. The new source of highly effective Mlo powdery mildew resistance that is described in this study could be used in barley breeding programs.

Pathogenic and molecular variation of Fusarium species causing head blight on barley landraces

Fusarium head blight (FHB) is consistently one of the most important barley diseases worldwide. This study aimed to evaluate the pathogenicity of 16 isolates of four Fusarium species under controlled conditions and their genetic variability using 22 random amplified polymorphic DNA (RAPD) markers. Pathogenic variation was characterized based on disease development rates and disease index on two Syrian barley landraces with varying resistance to FHB, Arabi Aswad (AS) and Arabi Abiad (AB). Significant differences in intra- and inter-Fusarium species pathogenicity and in susceptibility between the above-mentioned cultivars were highlighted. Overall, the two barley landraces showed moderately susceptible to moderately resistance levels to fungal infection and FHB spread within the head. Quantitative traits showed significant correlation with previous data generated in vitro and under field conditions, suggesting that growth chamber indices can predict fungal pathogenicity and quantitative disease resistance generated under various experimental conditions. Based on PCR amplification with seven different primers, the isolates showed genetic variation. Dendrogram generated by cluster analysis based on RAPD markers data showed two main groups, suggesting that a possible clonal origin could exist in the four Fusarium species. RAPD fingerprints are not useful to distinguish the 16 Fusarium isolates with different levels of pathogenicity.

Assessment on the Current State of On-Farm Diversity and Genetic Erosion in Barley (Hordeum vulgare L.) Landraces from Bale Highlands, Southeast Ethiopia

Barley landraces is among the major cereal crops grown in Ethiopian highlands including Bale highlands. However, in recent days, the crop is highly declining to the extents of total loss. This study was, therefore, aimed at assessing the extents of its on-farm diversity and genetic erosion from Bale highlands, Ethiopia. Data were generated from twelve administrative districts and analyzed considering important ecological and genetic erosion models. A total of 25 distinct (at least in naming) barley landraces with varying distribution patterns have been identified in the areas. Landrace richness ( R ) revealed higher magnitude among all the study districts, the smallest being 2.02 ( D Mg ) and 1.41 ( D Mn ) and considerable range of variations ( D Mg = 2.02 to 5.02, D Mn = 1.41 to 3.17). Among the study districts, Dinsho consisted the highest on-farm diversity estimate ( D Mg = 5.02 , D Mn = 3.17 ) followed by Goba and Sinana ( D Mg = 4.50 and 3.97; D Mn = 2.87 and 2.57 in that order). Estimate of the landrace evenness ( E ) also showed the highest magnitude (>0.95) except in Agarfa district (0.77). The result suggests potentiality of the areas and wide cultivation of majority of the landraces in the villages. However, nowadays, only 14 landraces are under cultivation and the remaining 11 are totally eroded from the district(s) constituting the highest (56.0%) combined genetic erosion suggesting loss of important agronomic traits and, thus, a major bottleneck for further improvement and conservation plans. Thus, attention should be payed to conserving the landraces for better further use.

Multifaceted Analysis of Barley Landraces Collected during Gene Bank Expeditions in Poland at the End of the 20th Century

The extensive genetic diversity of crop landraces deposited in gene banks is an important part of future breeding programs. However, in order to exploit this potential, it is necessary both to preserve germplasm and to collect and share a wide range of data on its characteristics and evaluation. The main objective of the presented paper was to evaluate the diversity of spring barley landraces originating from Poland. Historical data from standard field evaluation of agronomic traits, genetic data obtained from Inter Simple Sequence Repeat (ISSR) analysis and grain morphometric data were used. The analysis showed that groups of hulled and hulls barley accessions were substantially separate. Genetic and grain morphological variation did not show any relationship with eco-geographical conditions in the place of origin. There was also no clear division into forms with two- and six-row ears. The combination of the results of various types of analyzes describing this collection makes us believe that its chances of being used in research and breeding will increase.

The influence of breeding history, origin and growth type on population structure of barley as revealed by SSR markers

Natural and mass selection during domestication and cultivation favored particular traits of interest in barley. In the present study, population structure, and genetic relationships among 144 accessions of barley landraces and breeding materials from various countries were studied using a set of 77 and 72 EST-SSR and gSSR markers, respectively distributed on seven chromosomes of barley. In total, 262 and 429 alleles were amplified in 77 EST-SSRs and 72 gSSR loci, respectively. Out of which, 185 private/group-specific alleles were identified in the landraces compared with 14 in "cultivar and advanced breeding lines", indicating the possibility to introgress favorite alleles from landraces into breeding materials. Comparative analysis of genetic variation among breeding materials, Iranian landraces, and exotic landraces revealed higher genetic diversity in Iranian landraces compared with others. A total of 37, 15, and 14 private/group-specific alleles were identified in Iranian landraces, exotic landraces, and breeding materials, respectively. The most likely groups for 144 barley genotypes were three as inferred using model- and distance-based clustering as well as principal coordinate analysis which assigned the landraces and breeding materials into separate groups. The distribution of alleles was found to be correlated with population structure, domestication history and eco-geographical factors. The high allelic richness in the studied set of barley genotype provides insights into the available diversity and allows the construction of core groups based on maximizing allelic diversity for use in barley breeding programs.