Barley Breeding Programs Research Articles

Seedling and adult‐plant stage resistance of a world collection of barley genotypes to stripe rust

AbstractBarley stripe rust caused by Puccinia striiformis f.sp. hordei (PSH) is one of the major diseases in barley production regions worldwide. A total of 336 barley genotypes with diverse genetic backgrounds targeted for low‐input barley production were tested for seedling and adult‐plant stage resistance against six PSH races (0S0, 0S0‐1, 1S0, 4S0, 5S0 and 7S0) originated from India. The seedling resistance was evaluated by inoculating the barley genotypes with six races separately under controlled conditions in Shimla, India. The same barley genotypes were evaluated for adult‐plant stage resistance in the Agricultural Research Station (ARS) of Rajasthan Agriculture University, Durgapura, Rajasthan, India. Out of the 336 barley genotypes tested for seedling resistance, 119 (35.4%), 101 (30.1%), 87 (25.9%), 100 (29.8%), 91 (27.1%) and 70 (20.8%) genotypes were resistant to races 0S0, 0S0‐1, 1S0, 4S0, 5S0 and 7S0, respectively. In the field, 102 (30.3%) genotypes showed the resistance response of which 18 (5.3%) genotypes were highly resistant to PSH. Barley genotypes AM‐14, AM‐177, AM‐37, AM‐120, AM‐300, AM‐36, AM‐103, AM‐189, AM‐291, AM‐275 and AM‐274 showed resistance response to all six races at seedling and adult‐plant stages. Seedling resistance reported in the current study is effective against the newly emerged race 7S0 and previously reported five races in India. Therefore, resistant barley genotypes identified in the current study provided effective protection against all six races at seedling and adult‐plant stages. The stripe rust resistance identified in the current studies may be potential donors of stripe rust resistance to barley breeding programmes in India and elsewhere.

QTL controlling grain filling under terminal drought stress in a set of wild barley introgression lines.

Drought is a major abiotic stress impeding the yield of cereal crops globally. Particularly in Mediterranean environments, water becomes a limiting factor during the reproductive developmental stage, causing yield losses. The wild progenitor of cultivated barley Hordeum vulgare ssp spontaneum (Hsp) is a potentially useful source of drought tolerance alleles. Wild barley introgression lines like the S42IL library may facilitate the introduction of favorable exotic alleles into breeding material. The complete set of 83 S42ILs was genotyped with the barley 9k iSelect platform in order to complete genetic information obtained in previous studies. The new map comprises 2,487 SNPs, spanning 989.8 cM and covering 94.5% of the Hsp genome. Extent and positions of introgressions were confirmed and new information for ten additional S42ILs was collected. A subset of 49 S42ILs was evaluated for drought response in four greenhouse experiments. Plants were grown under well-watered conditions until ten days post anthesis. Subsequently drought treatment was applied by reducing the available water. Several morphological and harvest parameters were evaluated. Under drought treatment, trait performance was reduced. However, there was no interaction effect between genotype and treatment, indicating that genotypes, which performed best under control treatment, also performed best under drought treatment. In total, 40 QTL for seven traits were detected in this study. For instance, favorable Hsp effects were found for thousand grain weight (TGW) and number of grains per ear under drought stress. In particular, line S42IL-121 is a promising candidate for breeding improved malting cultivars, displaying a TGW, which was increased by 17% under terminal drought stress due to the presence of an unknown wild barley QTL allele on chromosome 4H. The introgression line showed a similar advantage in previous field experiments and in greenhouse experiments under early drought stress. We, thus, recommend using S42IL-121 in barley breeding programs to enhance terminal drought tolerance.

Pathotypes of Pyrenophora teres on barley in Turkey

Net blotch foliar diseases of barley are important in Turkey, lowering grain yields and quality. There are two forms, the spot form (caused by Pyrenophora teres f. maculata ( Ptm )) and the net form (caused by P. teres f. teres ( Ptt )) . To determine the pathotypes of Ptt and Ptm in Turkey, surveys were carried out during 2012, 2013 and 2015. Pyrenophora teres samples were collected from 34 provinces of Turkey. From these samples, 258 Ptm and 167 Ptt single conidium isolates were obtained. Pathotypes of 50 P. teres f. maculata and 40 P. teres f. teres isolates were assessed by inoculating onto a differential set of 25 barley genotypes. Twenty six Ptm pathotypes and 24 Ptt pathotypes were identified, and significant pathogenic variation was found among the isolates. Barley breeding programmes in Turkey should consider the pathotypes identified for incorporation of net blotch resistance. Continuous virulence monitoring for the P. teres population should be carried out to inform resistance breeding priorities.

Genetic Mapping of Quantitative Trait Loci for Yield-Affecting Traits in a Barley Doubled Haploid Population Derived from Clipper × Sahara 3771.

Many traits play essential roles in determining crop yield. Wide variation for morphological traits exists in Hordeum vulgare L., but the genetic basis of this morphological variation is largely unknown. To understand genetic basis controlling morphological traits affecting yield, a barley doubled haploid population (146 individuals) derived from Clipper × Sahara 3771 was used to map chromosome regions underlying days to awn appearance, plant height, fertile spike number, flag leaf length, spike length, harvest index, seed number per plant, thousands kernel weight, and grain yield. Twenty-seven QTLs for nine traits were mapped to the barley genome that described 3–69% of phenotypic variations; and some genomic regions harbor a given QTL for more than one trait. Out of 27 QTLs identified, 19 QTLs were novel. Chromosomal regions on 1H, 2H, 4H, and 6H associated with seed grain yield, and chromosome regions on 2H and 6H had major effects on grain yield (GY). One major QTL for seed number per plant was flanked by marker VRS1-KSUF15 on chromosome 2H. This QTL was also associated with GY. Some loci controlling thousands kernel weight (TKW), fertile spike number (FSN), and GY were the same. The major grain yield QTL detected on linkage PSR167 co-localized with TAM10. Two major QTLs controlling TKW and FSN were also mapped at this locus. Eight QTLs on chromosomes 1H, 2H, 3H, 4H, 5H, 6H, and 7H consistently affected spike characteristics. One major QTL (ANIONT1A-TACMD) on 4H affected both spike length (SL) and spike number explained 9 and 5% of the variation of SL and FSN, respectively. In conclusion, this study could cast some light on the genetic basis of the studied pivotal traits. Moreover, fine mapping of the identified major effect markers may facilitate the application of molecular markers in barley breeding programs.

A 191-bp insertion/deletion in GBSS1 region is responsible for the changes in grain amylose content in barley (Hordeum vulgare L.)

Amylose concentration in barley grain is one of the important quality traits. In this study, a major quantitative trait locus (QTL) for grain amylose content was identified from a doubled haploid (DH) population. This QTL was also detected from genome-wide association studies (GWAS) using 185 diverse barley germplasm. The waxy (GBSS1) gene was located in the QTL region and could be a candidate gene. Subsequent characterization of waxy alleles of two parents of the DH population revealed that a 191-bp insertion in the region from the transcription start site to start codon is responsible for the reduction of waxy transcript, leading to a lower expression level, thus, a lower amylose content. A genetic marker was designed for the waxy allele and can be effectively used in barley breeding programs.

English

Barley is a major cereal grown widely and used in several food products, beverage production and animal feed.  Being the fourth most important cereal crop in the world and the fifth rank in Ethiopia, it is a cash crop and used as a source of malt by the brewery industries, as food for human and feed for animals. Genetic diversity assessment is a key component in breeding programs. High level of polymorphism, codominant and multi allelic nature of simple sequence repeats (SSRs) markers make them preferable for diversity analysis in plant species. In this study, 22 SSRs markers were used to characterize the genetic diversity of 39 released and elite barley varieties collected from barley breeding program in Ethiopia. The amplification of SSRs loci were obtained for 35 primer pairs and only 22 of them showed clear polymorphic patterns which produced a total of 73 alleles with an average of 5 alleles per locus. The data generated by these informative primers were sufficient to discriminate the analysed barley genotypes. Based on the dissimilarity matrices ranging from 0.11 to 0.58, the genotypes were grouped into three major groups. The calculated polymorphism information content (PIC) values ranges from 0.17 to 0.60 with an average of 0.47 which shows the importance of the markers for future diversity analysis of barley. Locus HVACL1 and HVM36 shows higher PIC and locus HVBDHN7 shows lower PIC in this characterized barley genotype. This result will be useful for barley germplasm management and improvement in terms of biodiversity protection and design of new crosses for future breeding purpose.   Key words: Barley, elite, polymorphism information content (PIC), released, similarity, simple sequence repeats (SSRs), varieties.

QTL analysis in Barley Across Environments in Egypt

BARLEY is one of the most important cereal crops worldwide. An advanced backcross doubled haploid mapping population was grown in four locations across Egypt (Assuit, Al Wady Al Asuity, Matrouh and Nubaria). The population included 301 BC2DH lines derived from crossing between a German elite cultivar of H. vulgare ssp. vulgare ‘Scarlett’ with an exotic accession of H. vulgare ssp. spontaneum ‘ISR42-8’. A linkage map including 371 different types of genetic markers was used to perform QTL analysis. We detected 56 putative QTLs for traits of interest. In addition, the study identified four markers with marker main and marker × environment interaction effects. The exotic alleles of those four markers could be responsible for increasing their traits across environments. Furthermore, eight markers showed pleiotropic effect across locations. Some DH lines performed better than their parents and check varieties in each environment and across four environments as well. These results might be useful in MAS for barley breeding programs in Egypt.

شناسایی ژنوتیپ های جو (Hordeum vulgare L.) متحمل به خشکی با استفاده از شاخصهای تحمل تنش

تنش خشکی انتهای فصل از مهم‌ترین عوامل محدودکننده تولید محصولات کشاورزی است. به‌منظور شناسایی ارقام متحمل به خشکی جو از بین 79 رقم خارجی و یک رقم شاهد ایرانی و نیز تعیین ارتباط بین اجزای عملکرد با شاخص‌های تحمل به تنش، آزمایشی تحت شرایط آبیاری نرمال و تنش آبی در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه شیراز انجام شد. از بین شاخص‌های مختلف تحمل به خشکی،MP، HMP، GMPو STIبیشترین همبستگی مثبت و معنی‌دار را با عملکرد در هردو شرایط آبیاری نرمال و تنش آبی نشان دادند و به‌عنوان بهترین معیارهای تعیین ارقام متحمل تعیین گردیدند. بعلاوه، عملکرد بیولوژیک، تعداد سنبله و وزن صد دانه در هر دو شرایط همبستگی مثبت و معنی‌داری را با شاخص‌های تحمل نشان دادند. با توجه به نتایج تجزیه به مؤلفه‌های اصلی، دو مؤلفه اول توانستند درمجموع 97 درصد از تغییرات را توجیه نمایند که مؤلفه اول به‌عنوان مؤلفه مقاومت و پایداری عملکرد و مؤلفه دوم به‌عنوان مؤلفه حساسیت معرفی شدند. با توجه به آنالیزهای آماری مختلف انجام‌شده ارقام 88 و 145 به‌عنوان متحمل‌ترین ارقام شناسایی شدند. تجزیه خوشه‌ای بر اساس شاخص‌های تحمل تنش و عملکرد در هر دو شرایط تنش و بدون تنش 80 رقم موردبررسی را در چهار گروه مجزا قرارداد. نتایج این تحقیق منبع مناسبی برای استفاده در برنامه‌های اصلاحی ارقام جو پاییزه برای افزایش تنوع ژنتیکی ژرم پلاسم ایرانی و نیز تولید ارقام متحمل به خشکی فراهم می‌آورد.

Association mapping utilizing diverse barley lines reveals net form net blotch seedling resistance/susceptibility loci.

A diverse collection of barley lines was phenotyped with three North American Pyrenophora teres f. teres isolates and association analyses detected 78 significant marker-trait associations at 16 genomic loci. Pyrenophora teres f. teres is a necrotrophic fungal pathogen and the causal agent of the economically important foliar disease net form net blotch (NFNB) of barley. The deployment of effective and durable resistance against P. teres f. teres has been hindered by the complexity of quantitative resistance and susceptibility. Several bi-parental mapping populations have been used to identify QTL associated with NFNB disease on all seven barley chromosomes. Here, we report the first genome-wide association study (GWAS) to detect marker-trait associations for resistance or susceptibility to P. teres f. teres. Geographically diverse barley genotypes from a world barley core collection (957) were genotyped with the Illumina barley iSelect chip and phenotyped with three P. teres f. teres isolates collected in two geographical regions of the USA (15A, 6A and LDNH04Ptt19). The best of nine regression models tested were identified for each isolate and used for association analysis resulting in the identification of 78 significant marker-trait associations (MTA; -log10p value >3.0). The MTA identified corresponded to 16 unique genomic loci as determined by analysis of local linkage disequilibrium between markers that did not meet a correlation threshold of R 2 ≥ 0.1, indicating that the markers represented distinct loci. Five loci identified represent novel QTL and were designated QRptts-3HL, QRptts-4HS, QRptts-5HL.1, QRptts-5HL.2, and QRptts-7HL.1. In addition, 55 of the barley lines examined exhibited a high level of resistance to all three isolates and the SNP markers identified will provide useful genetic resources for barley breeding programs.

“Women’s empowerment through seed improvement and seed governance: Evidence from participatory barley breeding in pre-war Syria”

Approaches to food security primarily focus on technological solutions, seeking to produce more food, preferably with fewer resources. It has been argued that access to food involves issues of resource distribution and social marginalization. Governance is seen as one of the keys to redressing the institutional inequity that affects resource distribution. Rural women’s empowerment is seen as a means to reduce social marginalization and to hasten progress towards hunger eradication and gender equitable institutions. Building on the empirical findings of a six-year study (2006–2011) undertaken in the context of a participatory barley breeding (PBB) programme in pre-war Syria, this paper establishes the links between women’s empowerment, seed improvement through PPB and seed governance vis-à-vis household food security. The study shows how the programme enhanced the empowerment of the respondent women and how gender-blind seed governance regimes at national and international levels restricted the empowerment of these women ultimately affecting the pillars of food security. We discuss some of the challenges encountered by the study in conceptualizing and operationalizing gender analysis to enhance women’s empowerment. The article further discusses the interplay of processes to both discipline gender norms and provides transformational opportunities towards gender equity created by public spaces such as the PBB programme. The article contributes to current discussions on the effective pathways to develop smallholder agriculture, enhance gender equity and enhance food security and rural livelihoods in the dry areas of the temperate world.

Marker development using SLAF-seq and whole-genome shotgun strategy to fine-map the semi-dwarf gene ari-e in barley.

BackgroundBarley semi-dwarf genes have been extensively explored and widely used in barley breeding programs. The semi-dwarf gene ari-e from Golden Promise is an important gene associated with some agronomic traits and salt tolerance. While ari-e has been mapped on barley chromosome 5H using traditional markers and next-generation sequencing technologies, it has not yet been finely located on this chromosome.ResultsWe integrated two methods to develop molecular markers for fine-mapping the semi-dwarf gene ari-e: (1) specific-length amplified fragment sequencing (SLAF-seq) with bulked segregant analysis (BSA) to develop SNP markers, and (2) the whole-genome shotgun sequence to develop InDels. Both SNP and InDel markers were developed in the target region and used for fine-mapping the ari-e gene. Linkage analysis showed that ari-e co-segregated with marker InDel-17 and was delimited by two markers (InDel-16 and DGSNP21) spanning 6.8 cM in the doubled haploid (DH) Dash × VB9104 population. The genetic position of ari-e was further confirmed in the Hindmarsh × W1 DH population which was located between InDel-7 and InDel-17. As a result, the overlapping region of the two mapping populations flanked by InDel-16 and InDel-17 was defined as the candidate region spanning 0.58 Mb on the POPSEQ physical map.ConclusionsThe current study demonstrated the SLAF-seq for SNP discovery and whole-genome shotgun sequencing for InDel development as an efficient approach to map complex genomic region for isolation of functional gene. The ari-e gene was fine mapped from 10 Mb to 0.58 Mb interval.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3247-4) contains supplementary material, which is available to authorized users.

Genome-Wide Association Study of Spot Form of Net Blotch Resistance in the Upper Midwest Barley Breeding Programs.

Pyrenophora teres f. maculata, the causal agent of spot form of net blotch (SFNB), is an emerging pathogen of barley in the United States and Australia. Compared with net form of net blotch (NFNB), less is known in the U.S. Upper Midwest barley breeding programs about host resistance and quantitative trait loci (QTL) associated with SFNB in breeding lines. The main objective of this study was to identify QTL associated with SFNB resistance in the Upper Midwest two-rowed and six-rowed barley breeding programs using a genome-wide association study approach. A total of 376 breeding lines of barley were evaluated for SFNB resistance at the seedling stage in the greenhouse in Fargo in 2009. The lines were genotyped with 3,072 single nucleotide polymorphism (SNP) markers. Phenotypic evaluation showed a wide range of variability among populations from the four breeding programs and the two barley-row types. The two-rowed barley lines were more susceptible to SFNB than the six-rowed lines. Continuous distributions of SFNB severity indicate the quantitative nature of SFNB resistance. The mixed linear model (MLM) analysis, which included both population structure and kinship matrices, was used to identify significant SNP-SFNB associations. Principal component analysis was used to control false marker-trait association. The linkage disequilibrium (LD) estimates varied among chromosomes (10 to 20 cM). The MLM analysis identified 10 potential QTL in barley: SFNB-2H-8-10, SFNB-2H-38.03, SFNB-3H-58.64, SFNB-3H-78.53, SFNB-3H-91.88, SFNB-3H-117.1, SFNB-5H-155.3, SFNB-6H-5.4, SFNB-6H-33.74, and SFNB-7H-34.82. Among them, four QTL (SFNB-2H-8-10, SFNB-2H-38.03 SFNB-3H-78.53, and SFNB-3H-117.1) have not previously been published. Identification of SFNB resistant lines and QTL associated with SFNB resistance in this study will be useful in the development of barley genotypes with better SFNB resistance.

Genomic Selection Performs Similarly to Phenotypic Selection in Barley

Genomic selection uses marker‐based predictions to improve and accelerate the breeding process. Numerous studies have investigated the accuracy of genomic predictions; however, few studies have directly compared genomic and phenotypic selection. We compared genomic and phenotypic selection in five sets of selection candidates from a barley breeding program. In each set, about 96 breeding lines were genotyped with 1536 single nucleotide polymorphism (SNP) markers and phenotyped for yield, Fusarium head blight (FHB) severity, and deoxynivalenol (DON) concentration. A set of 168 lines and the same set of SNP markers were used to train a prediction model and predict the performance of the selection candidates using ridge regression best linear unbiased prediction. The best‐performing 10% of the breeding lines in each selection candidate set were selected using both methods and revaluated in several trials. We found similar significant response to selection using genomic and phenotypic selection for FHB severity and DON concentration, and no significant response for yield using either method. For all traits, genomic selection significantly increased genetic similarity compared with the selection candidates. In addition, genomic selection, compared with phenotypic selection, resulted in an increase in the frequency of favorable alleles. Three indirect selection methods for DON concentration, (predicted FHB severity, empirical FHB severity, and predicted DON concentration) performed similarly to direct phenotypic selection for DON, but differed considerably in cost. We conclude that the use of genomic selection for yield and FHB breeding in barley should result in gains from response to selection that are similar to the gains obtained using phenotypic selection, but with a shorter breeding cycle time and lower cost.

Mapping and validation of major quantitative trait loci for kernel length in wild barley (Hordeum vulgare ssp. spontaneum)

BackgroundKernel length is an important target trait in barley (Hordeum vulgare L.) breeding programs. However, the number of known quantitative trait loci (QTLs) controlling kernel length is limited. In the present study, we aimed to identify major QTLs for kernel length, as well as putative candidate genes that might influence kernel length in wild barley.ResultsA recombinant inbred line (RIL) population derived from the barley cultivar Baudin (H. vulgare ssp. vulgare) and the long-kernel wild barley genotype Awcs276 (H.vulgare ssp. spontaneum) was evaluated at one location over three years. A high-density genetic linkage map was constructed using 1,832 genome-wide diversity array technology (DArT) markers, spanning a total of 927.07 cM with an average interval of approximately 0.49 cM. Two major QTLs for kernel length, LEN-3H and LEN-4H, were detected across environments and further validated in a second RIL population derived from Fleet (H. vulgare ssp. vulgare) and Awcs276. In addition, a systematic search of public databases identified four candidate genes and four categories of proteins related to LEN-3H and LEN-4H.ConclusionsThis study establishes a fundamental research platform for genomic studies and marker-assisted selection, since LEN-3H and LEN-4H could be used for accelerating progress in barley breeding programs that aim to improve kernel length.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0438-6) contains supplementary material, which is available to authorized users.

Virulence of Pyrenophora teres populations in western Canada

Net blotch, caused by Pyrenophora teres, is an economically important disease of barley. The pathogen has two morphologically similar but genetically distinct forms: P. teres f. teres (Ptt) and P. teres f. maculata (Ptm), which cause net form net blotch (NFNB) and spot form net blotch (SFNB), respectively. The virulence of a collection of 39 Ptt and 27 Ptm isolates collected from western Canada was evaluated by inoculating these isolates onto sets of barley differential hosts. One week following inoculation, the second and third leaves of each plant were rated for disease severity on scales of 1–10 (for Ptt) or 1–9 (for Ptm). Plants rated <5 and ≥5 were scored as resistant and susceptible to Ptt, respectively, while plants rated 1–3 and >3 were scored as resistant and susceptible to Ptm. The experiment was repeated. Cluster analysis revealed 16 and 13 distinct pathotype groups, respectively, among the 39 and 27 representative Ptt and Ptm isolates. The barley differentials CI 5791 and CI 9820 were resistant to all isolates of Ptt except one, whilst the differential CI 9214 was resistant to all isolates of Ptm except two. Therefore, the differential lines CI 5791 and CI 9820, for Ptt, and CI 9214, for Ptm, can still be considered as potentially useful sources of resistance for Canadian barley breeding programmes.

Assessment of genetic diversity in Brazilian barley using SSR markers.

Barley is a major cereal grown widely and used in several food products, beverage production and animal fodder. Genetic diversity is a key component in breeding programs. We have analyzed the genetic diversity of barley accessions using microsatellite markers. The accessions were composed of wild and domesticated barley representing genotypes from six countries and three breeding programs in Brazil. A total of 280 alleles were detected, 36 unique to Brazilian barley. The marker Bmag120 showed the greatest polymorphism information content (PIC), with the highest mean value found on chromosome three, and the lowest on chromosomes four and six. The wild accessions presented the highest diversity followed by the foreign genotypes. Genetic analysis was performed using Principal Coordinates Analysis, UPGMA clustering, and Bayesian clustering analysis implemented in Structure. All results obtained by the different methods were similar. Loss of genetic diversity has occurred in Brazilian genotypes. The number of alleles detected in genotypes released in 1980s was higher, whereas most of the cultivars released thereafter showed lower PIC and clustered in separate subgroups from the older cultivars. The use of a more diverse panel of genotypes should be considered in order to exploit novel alleles in Brazilian barley breeding programs.

Identification of aerenchyma formation-related QTL in barley that can be effective in breeding for waterlogging tolerance.

Aerenchyma formation after 7days of waterlogging in commercial potting mixture can be a reliable, fast, and widely utilized approach for the selection of waterlogging tolerant barley genotypes. One major QTL for aerenchyma formation after 7days of waterlogging treatment was identified and the newly developed markers explained 44% of the phenotypic variance. This QTL can now be effectively used in barley breeding programs. Waterlogging is one of the important limiting conditions for crop yield and productivity. The main feature of waterlogged soils is oxygen deprivation, due to slow gas diffusion in water. Decreased oxygen content in waterlogged soils leads to the oxygen deficiency in plant tissues, resulting in reduced energy availability for plants. Rapidly induced aerenchyma formation is critical to maintaining adequate oxygen supply and overall waterlogging tolerance in barley. In this study, we have proved that quantifying aerenchyma formation after 7days of waterlogging in commercial potting mixture can be a reliable, fast, and widely utilised approach for the selection of waterlogging tolerant barley genotypes, which is supported by measurements of redox potential (an indicator of anaerobic conditions). This protocol was also used to identify quantitative trait loci (QTL) in a doubled haploid population of barley from the cross between Yerong (tolerant) and Franklin (sensitive) genotypes. The QTL for aerenchyma formation and root porosity were at the same location as the waterlogging tolerance QTL. Seven new markers were developed and added onto this region on chromosome 4H. One major QTL for aerenchyma formation after 7days waterlogging treatment explained 44.0% of the phenotypic variance. This successful QTL for aerenchyma formation can be effectively used in the marker assisted selection to improve waterlogging tolerance in barley.

Identification of Quantitative Trait Loci for the Phenolic Acid Contents and Their Association with Agronomic Traits in Tibetan Wild Barley

Phenolic acids have been of considerable interest in human nutrition because of their strong antioxidative properties. However, even in a widely grown crop, such as barley, their genetic architecture is still unclear. In this study, genetic control of two main phenolic acids, ferulic acid (FA) and p-coumaric acid (p-CA), and their associations with agronomic traits were investigated among 134 Tibetan wild barley accessions. A genome-wide association study (GWAS) identified three DArT markers (bpb-2723, bpb-7199, and bpb-7273) associated with p-CA content and one marker (bpb-3653) associated with FA content in 2 consecutive years. The contents of the two phenolic acids were positively correlated with some agronomic traits, such as the first internode length, plant height, and some grain color parameters, and negatively correlated with the thousand-grain weight (TGW). This study provides DNA markers for barley breeding programs to improve the contents of phenolic acids.

Expression profiling of genes involved in drought stress and leaf senescence in juvenile barley.

BackgroundDrought stress in juvenile stages of crop development and premature leaf senescence induced by drought stress have an impact on biomass production and yield formation of barley (Hordeum vulgare L.). Therefore, in order to get information of regulatory processes involved in the adaptation to drought stress and leaf senescence expression analyses of candidate genes were conducted on a set of 156 barley genotypes in early developmental stages, and expression quantitative trait loci (eQTL) were identified by a genome wide association study.ResultsSignificant effects of genotype and treatment were detected for leaf colour measured at BBCH 25 as an indicator of leaf senescence and for the expression level of the genes analysed. Furthermore, significant correlations were detected within the group of genes involved in drought stress (r = 0.84) and those acting in leaf senescence (r = 0.64), as well as between leaf senescence genes and the leaf colour (r = 0.34). Based on these expression data and 3,212 polymorphic single nucleotide polymorphisms (SNP) with a minor allele frequency >5 % derived from the Illumina 9 k iSelect SNP Chip, eight cis eQTL and seven trans eQTL were found. Out of these an eQTL located on chromosome 3H at 142.1 cM is of special interest harbouring two drought stress genes (GAD3 and P5CS2) and one leaf senescence gene (Contig7437), as well as an eQTL on chromosome 5H at 44.5 cM in which two genes (TRIUR3 and AVP1) were identified to be associated to drought stress tolerance in a previous study.ConclusionWith respect to the expression of genes involved in drought stress and early leaf senescence, genotypic differences exist in barley. Major eQTL for the expression of these genes are located on barley chromosome 3H and 5H. Respective markers may be used in future barley breeding programmes for improving tolerance to drought stress and leaf senescence.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0701-4) contains supplementary material, which is available to authorized users.

Breeding barley for quality in Turkey

We evaluated a total of 411 genotypes, including 334 breeding lines with 77 checks from Barley (Hordeum vulgare L.) Breeding Program of Turkey (BBPT), based upon their grain yield (GY) and quality traits (namely protein content-PC, acid detergent fiber-ADF, thousand kernel weight-TKW, kernel size-KS and test weight-TW), during the 5 consecutive cropping seasons, from 2007-2008 to 2011-2012. Broad-sense heritability (H) values for quality traits were moderate (0.57-0.65), while it was low (0.43) for grain yield. Accordingly, grain physical features (namely TW, KS and TKW) were positively significantly correlated with GY, but negatively significantly correlated with PC. Results of our study showed that selection for GY and quality traits was less efficient than we expected, due to undesirable multi-variate correlations such as GY vs PC and low to moderate H values. Therefore, we tried to put suggestions forward to the BBPT, by following discussing about our ability to select for high GY and acceptable quality in barley.