Chinese Barley Research Articles

Development and Characterization of a New TILLING Population for Forward and Reverse Genetics in Barley (Hordeum vulgare L.).

Mutagenesis is an important tool in crop improvement and free of the regulatory restrictions imposed on genetically modified organisms. Barley (Hordeum vulgare L.) is a diploid species with a genome smaller than those of other members of the Triticeae crops, making it an attractive model for genetic studies in Triticeae crops. In this study, we report an ethyl methane sulfonate (EMS)-mutagenized population in the Chinese barley landrace TX9425, which is tolerant to both abiotic and biotic stress. A TILLING (Targeting Induced Locus Lesion in Genomes) population consisting of 2000 M2 lines was also constructed based on the CEL I enzyme with subsequent polyacrylamide electrophoresis, which decreased the cost and labor investment. The mutant phenotypes of the M2 and M3 generations were scored and revealed the presence of a wide spectrum of morphological diversity. The population was evaluated by screening for induced mutations in five genes of interest. A detailed analysis was performed for the HvGLR3.5 gene and three mutations were identified by screening in 2000 M2 lines. Two of three mutations displayed tuft and yellow striped leaves compared to the wild type. Altogether, our study shows the efficiency of screening and the great potential of the new TILLING population for genetic studies in the barley crop model system.

Time-course of genotype and hormone-related effects on callus proliferation in barley genetic transformation

Successful barley genetic transformation is dependent on genotype selection, which largely limits its molecular breeding. To elucidate the effects of genotype and hormone on callus induction and differentiation of barley, we investigated the growth performance of callus proliferation and differentiation of green spot in three Chinese cultivars (ZU9, ZU10 and Hua30), one Australian malting barley (Franklin) and one Scotland Whisky barley (Golden Promise). The three Chinese barley showed shorter spikes but larger immature embryos after flowering for 15 ​d than the other two genotypes. Golden Promise had the largest callus proliferation and green spot differentiation than the other genotypes. Meanwhile, ZU10 showed a relatively similar appearance and high efficiency to Golden Promise, which highlights its capacity for genetic modification. Golden Promise maintained relatively higher expression of hormone-related genes at almost all stages of callus proliferation, including auxin and cytokinin related HvPIN1, HvARF3, HvRR6 and HvWOX11, which may explain its higher efficiency in genetic transformation. Adjusting hormone concentration to 1 ​mg ​L−1 6-BA and 0.25 ​mg L−1 2,4-D in transition medium significantly increased green spot differentiation for most genotypes. These findings may provide useful information for overcoming genotype dependency with optimal hormones at callus proliferation stages of barley.

An Improved Inoculation Method to Detect Wheat and Barley Genotypes for Resistance to Fusarium Crown Rot.

Fusarium crown rot (FCR), caused by Fusarium species, is a serious soilborne fungal disease in many wheat growing regions in the world. A reliable FCR assessment method is essential for germplasm screening and host resistance studies. Here, we report a new assay in which we inoculated wheat seedlings grown in a glasshouse for FCR by injecting spore suspensions into the seedling stems. The effects of inoculum concentration and injection time points on disease severity were investigated. Of different treatments, the injection of 107 macroconidia/ml suspension at one leaf and one heart stage gave best results. A collection of 92 emmer-derived hexaploid bread wheats, 43 barley germplasms, and four wheat genotypes with known resistance levels to FCR was used to validate this new method. Repeatability of the two trials in the validation experiments was high (r = 0.97, P < 0.01). Two emmer-derived hexaploid bread wheat and three Chinese barley germplasms showed consistent resistance to FCR in multiple rounds of selection. The short timeframe of this assay for phenotypic screening makes it a valuable tool to eliminate germplasms with undesirable susceptibility to FCR at seedling stage before costly field assays.

Comparative proteomic analysis of different barley cultivars during seed germination

Malting quality is an important determinant of the barley grain value used in brewing. Malting process is an accurately controlled barley germination followed by kilning and is modified according to the characteristics of the barley variety. However, the genetic mechanism of malting difference among varieties is still not clear. The present study aims to analyze the mechanism of malting performance variance about the different cultivars, especially the Chinese barley Gan-7. We identified brewing performance variance of Gan-7, Copeland, Spartacus and determined the variation in proteomic profiles among these cultivars. 114 proteins with significant differences between cultivars were identified and the roles of differential expression proteins in malt quality discrimination were elucidated according to their putative functions. The differentially expressed proteins mainly related to genetic information processing and carbohydrate metabolism pathways. Among them, we find that the poor α-amylase activity of Gan-7 is related to the low abundance of α-amylase. The performance of Gan-7 may be partly attributed to the differentially expressed proteins involved in starch hydrolysis, PRs, hordoindoline, hordein, trypsin inhibitor processes. In the present study, only barley variety used for malting was considered, and this can explain the cultivar effect of malting. These results may provide clues for optimizing the malting process for Chinese domestic barley cultivars, especially Gan-7.

Effects of Two Starch Synthase IIa Isoforms on Grain Components and Other Grain Traits in Barley

Starch biosynthesis in cereal crops is a complex pathway regulated by multiple starch synthetic enzymes. Starch synthase IIa (SSIIa) is well-known to be one of the major starch synthases and is very important in amylopectin biosynthesis. It has significant effects on grain composition and kernel traits. However, there are few reports on the association of natural variation of SSIIa in barley and grain composition and characteristics. In this work, two SSIIa isoforms were first identified as SSIIaH and SSIIaL by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, mass spectrometry, and Western blotting. Sequence analysis of the SSIIa gene demonstrated that a 33 bp insertion coding a peptide of APPSSVVPAKK caused different SSIIa, e.g., SSIIaH and SSIIaL. Based on this molecular difference, a polymerase chain reaction marker was developed, which could be used to screen different SSIIa genotypes easily. Kernel hardness of SSIIaL genotypes was significantly higher than that of SSIIaH Chinese barley cultivars. The proportion of SSIIaL genotypes was extremely low in Australian barley cultivars (5/24) and much higher in Tibetan hull-less barley cultivars (46/74), consistent with the end-use requirements of barley grain. This study provided new information in barley endosperm starch synthesis and indicated that it is valuable for choosing the preferred SSIIa genotype according to the end-use requirements.

Mechanism and antibacterial activity of vine tea extract and dihydromyricetin against Staphylococcus aureus

Vine tea (Ampelopsis grossedentata) has been approved as a new food ingredient in 2013. Both vine tea extract (VTE) and its active ingredient, 2R, 3R-Dihydromyricetin (DMY), showed good antibacterial activity. The mechanism of VTE and DMY against Staphylococcus aureus were evaluated by morphology observation, cell membrane and wall assay, protein assay, and DNA assay in this study. The results of SEM and TEM revealed that the VTE and DMY changed the morphology of S. aureus. The leakage of AKPase and β-galactosidase in treated groups demonstrated that the membrane integrity of S. aureus was disrupted. Meanwhile, the results of protein assay showed that VTE and DMY inhibited the expression of total proteins, and decreased activities of a few energy metabolism enzymes, total ATPase. Moreover, spectral and competitive analysis revealed that VTE and DMY interacted with DNA by groove and intercalation binding. Finally, the suspension experiments of Chinese cabbage and barley showed that inhibitors had strong inhibitory effect on bacteria growth. Overall, the results suggested that VTE and DMY may be potential food preservatives for inhibiting pathogen.

Transcriptome Analysis Identifies Candidate Genes and Functional Pathways Controlling the Response of Two Contrasting Barley Varieties to Powdery Mildew Infection.

Powdery mildew caused by Blumeria graminis f. sp. hordei (Bgh) is one of the most serious diseases in barley. The numerous barley varieties across China provide valuable genetic resources to screen the resistant germplasm and to discover the primary genes of resistance to powdery mildew. In this study, Chinese barley variety Feng 7 was identified as a highly resistant genotype which limited Bgh colonization by cell apoptosis using leaf staining assay, while another variety Hua 30 showed high susceptibility. The performance of high resistance to Bgh in F1 plants from the two varieties suggested dominant gene(s) controlled the resistance to powdery mildew in Feng 7. To understand the host transcriptional response to Bgh infection, these two barley varieties Feng 7 and Hua 30 were inoculated with Bgh, and their transcriptional profiling using RNA sequencing (RNA-seq) at four time points (12 h post-inoculation (hpi), 24 hpi, 48 hpi, and 72 hpi) were compared. 4318 differentially expressed genes (DEGs), including 2244 upregulated and 2074 downregulated genes, were detected in Feng 7, compared with Hua 30 at 12 hpi. 4907 DEGs (2488 upregulated and 2419 downregulated) were detected at 24 hpi. 4758 DEGs (2295 upregulated and 2463 downregulated) were detected at 48 hpi. 3817 DEGs (2036 upregulated and 1781 downregulated) were detected at 72 hpi. The results showed the number of DEGs between two varieties peaked at 24 hpi (for the upregulated) or 48 hpi (for the downregulated), which is matched with the processing of Bgh infection. In addition, the number of upregulated DEGs involved in the functional pathways of plant defense (mitogen-activated protein kinase (MAPK) pathway and plant hormone signal transduction) is elevated remarkably at 24 hpi. Six candidate genes (PR13, glutaredoxin, alcohol dehydrogenase, and cytochrome P450) were identified in Feng 7. All of them present continuous expression at higher levels upon Bgh infection, compared with the performance in Hua 30, which revealed the potential contribution to Feng 7 mediate resistance to Bgh. In conclusion, the candidate genes and relevant pathways provided key information towards understanding the defense of barley to Bgh attack and the molecular mechanisms of different genetic resistance to powdery mildew.

Leaf blight caused by Curvularia coicis on Chinese pearl barley (Coix chinensis) in Fujian Province, China

Chinese pearl barley (Coix chinensis Tod.) is grown worldwide as a cereal food and medicinal plant. During 2016 and 2017, a severe leaf blight outbreak was observed in Nanjing prefecture, Fujian Province, China. The disease outbreak affected almost 100% of the Chinese pearl barley plants under field conditions. The pathogen was isolated from infected leaves showing typical symptoms of dark brown spots surrounded by yellow halos, and was identified as Curvularia coicis Castellani based on morphological characteristics and sequencing of the ribosomal DNA internal transcribed spacer (rDNA-ITS). The optimal temperature for mycelial growth of C. coicis on potato dextrose agar (PDA) ranged from 25°C to 28°C. Pathogenicity assays were performed using Chinese pearl barley ‘Longyi 1' at the seven- to eight-leaf stage. Overall, C. coicis had a high virulence on these inoculated plants, even in the absence of wounds, and the pathogen was successfully reisolated. The results from this study identified the causal organism of leaf blight on Chinese pearl barley.

Complete Genome Sequence of Lactobacillus reuteri WHH1689, Isolated from Traditional Chinese Highland Barley Wine.

ABSTRACTHere, we report the complete genome sequence of Lactobacillus reuteri WHH1689, which was isolated from traditional Chinese highland barley wine in the Tibetan Plateau of China. The genome consists of a circular chromosome (2.04 Mb).

Inheritance and characterization of the new and rare gene Rph25 conferring seedling resistance in Hordeum vulgare against Puccinia hordei

AbstractIn this study, we characterized and mapped a new and rare resistance gene (RphFT) in the Chinese barley variety ‘Fong Tien’. RphFT, a dominant gene, was mapped to chromosome 5HL at a genetic position of 142.1 cM using DArT‐seq markers. The gene was also confirmed to be present in Australian cultivar ‘Yagan’ based on allelic tests, and likely ‘Lockyer’ based on multipathotype tests. The genetic studies also confirmed the presence of Rph12 in Australian cultivar ‘Baudin’. Rph12 is also located on chromosome 5HL close to RphFT, and the two loci were confirmed to be independent. Gene RphFT is of limited breeding value because it is effective to only one pathotype of P. hordei, 220P+ +Rph13 in Australia; nevertheless, it may play a role in controlling leaf rust if used in combination with other Rph genes. The locus symbol Rph25 is recommended for RphFT in accordance with the rules and numbering system of barley gene nomenclature.

ГЕНЕТИЧЕСКИЙ КОНТРОЛЬ УЛЬТРАСКОРОСПЕЛОСТИ МЕСТНЫХ ОБРАЗЦОВ ЯЧМЕНЯ ИЗ КИТАЯ

Ultra-early maturity of the Chinese barley landraces k-15881 (Hordeum vulgare L. var. coeleste L.) and k-15882 (var. nudipyramidatum Koern.) from VIR’s barley collection is controlled by three identical recessive genes. This homozygous genotype determines the period from shoot emergence to heading =32 days, with two recessives genes =36 days, and with one =40 days. One dominant allele of the gene contributes approximately 4 days to the earliness. New breeding source material with different times of heading to develop adaptable cultivars may be obtained by crossing these forms with later maturing commercial cultivars.

A new allele for aluminium tolerance gene in barley (Hordeum vulgare L.).

BackgroundAluminium (Al) toxicity is the main factor limiting the crop production in acid soils and barley (Hordeum vulgare L.) is one of the most Al-sensitive of the small-grained cereals. The major gene for Al tolerance in barley is HvAACT1 (HvMATE) on chromosome 4H which encodes a multidrug and toxic compound extrusion (MATE) protein. The HvAACT1 protein facilitates the Al-activated release of citrate from root apices which protects the growing cells and enables root elongation to continue. A 1 kb transposable element-like insert in the 5’ untranslated region (UTR) of HvAACT1 is associated with increased gene expression and tolerance and a PCR-based marker is available to score for this insertion.ResultsWe screened a wide range of barley genotypes for Al tolerance and identified a moderately tolerant Chinese genotype named CXHKSL which did not show the typical allele in the 5’ UTR of HvAACT1 associated with tolerance. We investigated the mechanism of Al tolerance in CXHKSL and concluded it also relies on the Al-activated release of citrate from roots. Quantitative trait loci (QTL) analysis of double haploid lines generated with CXHKSL and the Al-sensitive variety Gairdner mapped the tolerance locus to the same region as HvAACT1 on chromosome 4H.ConclusionsOur results show that the Chinese barley genotype CXHKSL possesses a novel allele of the major Al tolerance gene HvAACT1.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2551-3) contains supplementary material, which is available to authorized users.

Fine mapping of barley locus Rps6 conferring resistance to wheat stripe rust.

Key messageBarley resistance to wheat stripe rust has remained effective for a long time and, therefore, the genes underlying this resistance can be a valuable tool to engineer durable resistance in wheat.Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a major disease of wheat that is causing large economic losses in many wheat-growing regions of the world. Deployment of Pst resistance genes has been an effective strategy for controlling this pathogen, but many of these genes have been defeated by new Pst races. In contrast, genes providing resistance to this wheat pathogen in other grass species (nonhost resistance) have been more durable. Barley varieties (Hordeum vulgare ssp. vulgare) are predominately immune to wheat Pst, but we identified three accessions of wild barley (Hordeum vulgare ssp. spontaneum) that are susceptible to Pst. Using these accessions, we mapped a barley locus conferring resistance to Pst on the distal region of chromosome arm 7HL and designated it as Rps6. The detection of the same locus in the cultivated barley ‘Tamalpais’ and in the Chinese barley ‘Y12’ by an allelism test suggests that Rps6 may be a frequent component of barley intermediate host resistance to Pst. Using a high-density mapping population (>10,000 gametes) we precisely mapped Rps6 within a 0.14 cM region (~500 kb contig) that is colinear to regions in Brachypodium (<94 kb) and rice (<9 kb). Since no strong candidate gene was identified in these colinear regions, a dedicated positional cloning effort in barley will be required to identify Rps6. The identification of this and other barley genes conferring resistance to Pst can contribute to our understanding of the mechanisms for durable resistance against this devastating wheat pathogen.

Allelic variation and geographic distribution of vernalization genes HvVRN1 and HvVRN2 in Chinese barley germplasm

Knowledge of the allelic variation and epistatic interaction of vernalization genes is crucial to understanding seasonal growth habit and adaptability of genetic resources in cultivated (Hordeum vulgare) and wild (Hodeum spontaneum) barley. In this research, 1398 Chinese barley accessions were characterized with molecular markers for vernalization genes HvVRN1 and HvVRN2. Different combinations of haplotypes at these two vernalization genes were present at different frequencies in wild barley, landraces and modern cultivars. All of the HvVRN1 haplotypes except HvVRN1-7 (V 1-7 ) and HvVRN1-Hs (V 1-Hs ) were identified in the Chinese barley collection chosen for this study. Haplotype V 1-8 occurred at the highest frequency in spring V 1 alleles, and V 1-1 , V 1-4 and V 1-8 had broad geographic distributions in China. Haplotypes V 1-2 and V 1-3 are restricted to modern cultivars as they were introduced from exotic germplasm. A total of 18 HvVRN1/HvVRN2 multilocus haplotypes were identified. Most of the HvVRN1/HvVRN2 haplotypes were present in materials from the Yellow-Huai River Valley and Middle-Lower Yangtze Valley ecological zones, birthplace of Chinese farming. The predominant combinations in landraces were V 1-8 /V 2 and v 1 /V 2 , but v 1 /v 2 made up the highest proportion of modern cultivars. Haplotypes V 1-5 /v 2 , V 1-10 /V 2 and V 1-9 /V 2 showed a correlation with region. Our results confirmed the presence or absence of conserved regulatory elements and the length of the first intron of HvVRN1 plays a determinant role in the vernalization requirement of barley. This study provides useful information for breeding and utilization of Chinese barley germplasm.

POD promoted oxidative gelation of water-extractable arabinoxylan through ferulic acid dimers. Evidence for its negative effect on malt filterability

As a major component of non-starch polysaccharide in barley, arabinoxylan (AX) plays an important role in quality traits of malt and the final beer product. The Chinese barley malt has encountered filterability problems for a long time. The main reason caused by barley cultivar has been accepted in the malting and brewing industries. In our previous proteomic study, the peroxidase (POD) BP1 was found to be in quite high abundant in the filterability defect Chinese barley malt. Therefore, the present study tried to verify its negative effect on filterability, by surveying its activity in different malt samples and detecting effects of POD on AX gelation and filterability. The results showed that the activity of POD, as well as the content of AX bounded ferulic acid, were both negatively correlated with filterability, while the feruloyl esterase activity was positively correlated with it. In addition, AX gelation catalyzed by POD caused worse filterability, and the natural inhibitor of POD, vitamin C, could blocked the cross linking catalyzed by POD and thus improve the filterability. These results all suggested the great negative effect of POD on malt filterability.

Quantitative Trait Loci for Salinity Tolerance Identified under Drained and Waterlogged Conditions and Their Association with Flowering Time in Barley (Hordeum vulgare. L).

IntroductionSalinity is one of the major abiotic stresses affecting crop production via adverse effects of osmotic stress, specific ion toxicity, and stress-related nutritional disorders. Detrimental effects of salinity are also often exacerbated by low oxygen availability when plants are grown under waterlogged conditions. Developing salinity-tolerant varieties is critical to overcome these problems, and molecular marker assisted selection can make breeding programs more effective.MethodsIn this study, a double haploid (DH) population consisting of 175 lines, derived from a cross between a Chinese barley variety Yangsimai 1 (YSM1) and an Australian malting barley variety Gairdner, was used to construct a high density molecular map which contained more than 8,000 Diversity Arrays Technology (DArT) markers and single nucleotide polymorphism (SNP) markers. Salinity tolerance of parental and DH lines was evaluated under drained (SalinityD) and waterlogged (SalinityW) conditions at two different sowing times.ResultsThree quantitative trait loci (QTL) located on chromosome 1H, single QTL located on chromosomes 1H, 2H, 4H, 5H and 7H, were identified to be responsible for salinity tolerance under different environments. Waterlogging stress, daylight length and temperature showed significant effects on barley salinity tolerance. The QTL for salinity tolerance mapped on chromosomes 4H and 7H, QSlwd.YG.4H, QSlwd.YG.7H and QSlww.YG.7H were only identified in winter trials, while the QTL on chromosome 2H QSlsd.YG.2H and QSlsw.YG.2H were only detected in summer trials. Genes associated with flowering time were found to pose significant effects on the salinity QTL mapped on chromosomes 2H and 5H in summer trials. Given the fact that the QTL for salinity tolerance QSlsd.YG.1H and QSlww.YG.1H-1 reported here have never been considered in the literature, this warrants further investigation and evaluation for suitability to be used in breeding programs.

Identification and distribution of VERNALIZATION1 alleles in Chinese barley (Hordeum vulgare) germplasm

VERNALIZATION1 (VRN1) is a central regulator of the vernalization requirement, which affects the yield and geographical distribution of Triticeae crops through regulation of the flowering time. The first intron (Intron I) of VRN1 contains putative cis-elements that mediate repression of VRN1 expression. Allelic variations in Intron I are closely associated with increased VRN1 expression in vernalization-responsive accessions in the absence of vernalization. In this study, diagnostic molecular markers were developed to distinguish the main 12 known alleles, including a new allele, of barley (Hordeum vulgare) VRN1 (HvVRN1), and to investigate HvVRN1 alleles in 373 barley varieties from major agroecological regions in China. The new allele, HvVRN1-11, with a 3172-bp deletion in Intron I of HvVRN1, was identified in a Chinese barley landrace. Analysis of eight polymorphic sites flanking major variations in Intron I of HvVRN1 classified the 12 HvVRN1 alleles into five distinct groups. Compared with modern commercial barley, landraces possessed greater genetic diversity and contained the majority of HvVRN1 alleles, especially in the winter barley regions. HvVRN1 diversity in terms of allele number reduced significantly (P < 0.01) along with higher growing latitudes, but increased in accessions carrying the winter HvVRN2 allele. Wild-type HvVRN1 and the HvVRN1-8 allele showed the most widespread distribution in most regions whereas HvVRN1-1 & HvVRN1-8, and HvVRN1-5 are predominant in the Inner Mongolian Plateau spring barley region and the Northeast Plain spring barley region, respectively, with relatively higher latitudes. Compared with landraces, the frequency of HvVRN1-8 decreased while wild-type HvVRN1 increased significantly (P < 0.01) in commercial varieties. Our study classified HvVRN1 genetic diversity in a large collection of Chinese germplasm and provided a tool for identifying HvVRN1 alleles in barley breeding populations.

Molecular characterization of barley 3H semi-dwarf genes.

The barley chromosome 3H accommodates many semi-dwarfing genes. To characterize these genes, the two-rowed semi-dwarf Chinese barley landrace ‘TX9425’ was crossed with the Australian barley variety ‘Franklin’ to generate a doubled haploid (DH) population, and major QTLs controlling plant height have been identified in our previous study. The major QTL derived from ‘TX9425’ was targeted to investigate the allelism of the semi-dwarf gene uzu in barley. Twelve sets of near-isogenic lines and a large NILF2 fine mapping population segregating only for the dwarfing gene from ‘TX9425’ were developed. The semi-dwarfing gene in ‘TX9425’ was located within a 2.8 cM region close to the centromere on chromosome 3H by fine mapping. Molecular cloning and sequence analyses showed that the ‘TX9425’-derived allele contained a single nucleotide substitution from A to G at position 2612 of the HvBRI1 gene. This was apparently the same mutation as that reported in six-rowed uzu barley. Markers co-segregating with the QTL were developed from the sequence of the HvBRI1 gene and were validated in the ‘TX9425’/‘Franklin’ DH population. The other major dwarfing QTL derived from the Franklin variety was distally located on chromosome 3HL and co-segregated with the sdw1 diagnostic marker hv20ox2. A third dwarfing gene, expressed only in winter-sown trials, was identified and located on chromosome 3HS. The effects and interactions of these dwarfing genes under different growing conditions are discussed. These results improve our understanding of the genetic mechanisms controlling semi-dwarf stature in barley and provide diagnostic markers for the selection of semi-dwarfness in barley breeding programs.

Genetic Diversity Among Barley Varieties (Lines) Bred in China

To investigate the genetic variation level of Chinese barley varieties(lines) bred over recent years,the genetic diversity among 73 barley accessions from different growth regions were analyzed by 25 SSR markers on different locations of 7 linkage groups.2-6 alleles of each SSR locus were detected with an average of 3.92 alleles/locus.The variation of polymorphism information content(PIC) of each SSR marker ranged between 0.252 and 0.780 with an average of 0.569,showing a relative high detection ability of genetic polymorphism by SSR markers.The genetic similarity coefficient(GS) of malting barley varieties(lines) from different regions varied from 0.661 to 0.767 with an average of 0.714,and GS of hulless barley varieties(lines) in Tibet plateau varied from 0.533 to 0.925 with an average of 0.699.42 accessions of malting barley could be classified into 2 major groups at the level of GS 0.671,and 31 accessions of hulless barley could be classified into 5 groups at the level of GS 0.618.Majority of clusters/subclusters were found to contain accessions from the same geographic origins,showing a certain level of relationship between clustering and variety origin.In this study,SSR markers with high polymorphism were used to assess the genetic diversity of Chinese barley cultivars(lines).A poor genetic diversity still existed among these varieties(lines) and their genetic basis was rather narrow,which provided important reference for the selection and utilization of parental genotype in barley breeding project.

Identification and characterization of seedling and adult plant resistance to Puccinia hordei in Chinese barley germplasm

AbstractLeaf rust of barley, caused by Puccinia hordei, occurs in all barley‐growing regions of Australia causing significant yield losses under epidemic conditions. The development and use of resistant cultivars are the most economical and environmentally sustainable method to control leaf rust which in turn relies on ongoing efforts to identify and characterize new sources of resistance. The aim of this study was to postulate known genes and/or identify new sources of resistance to P. hordei. Fifty‐two genotypes were assessed at the seedling and adult plant growth stages. On the basis of multipathotype tests, 39 genotypes lacked detectable seedling resistance, and nine were postulated to carry the genes Rph2, Rph4, Rph12 and Rph19 singly. Four genotypes carried uncharacterized seedling resistance; however, the gene(s) present in each were ineffective to at least one of the pathotypes used. Field tests at the adult plant growth stage revealed the presence of adult plant resistance (APR) in 12 genotypes. Tests of allelism and marker analysis indicated that resistance genes present in these genotypes were independent of the APR gene Rph20.