Deriving a biophotothermal time scale for barley

Parameters for an equation representing crop development from planting to emergence, jointing, heading, soft dough and hard dough stages were obtained by iterative regression analysis of five years of temperature, photoperiod, and Olli barley phenological data from nine Canadian locations. The triquadratic model previously developed and applied to Marquis wheat by Robertson was used. The necessity of using the same threshold temperature for both the maximum and the minimum daily temperature causes analysis difficulties and makes the model less realistic. In spite of the model's limitations, the derived parameters are probably quite useful when applied under environmental conditions similar to those represented in the experiment. Under such conditions, the model seems to perform about as well for barley as it did for wheat, in spite of the considerable differences in the development behaviour of the two crops, especially barley's faster rate of development toward maturity.     

Molecular breeding for grain yield in barley: an evaluation of QTL effects in a spring barley cross

 We report results from a breeding strategy designed to accumulate favorable QTL alleles for grain yield identified in the SteptoeבMorex’ (SM) barley germplasm. Two map lines (SM73 and SM145) from the original mapping population were selected based on their marker genotype and QTL structure. When crossed, these lines would be expected to produce progeny with most favorable QTL alleles. One hundred doubled haploid (DH) lines from the F₁ hybrid of this cross were genotyped with ten RFLP markers and one morphological marker defining grain yield to monitor QTL segregation. A subset of 24 lines representing various combinations of putatively favorable and unfavorable QTL alleles, together with Steptoe, ‘Morex’, SM73, and SM145, were phenotyped for grain yield in five environments. Multiple regression procedures were used to explore phenotype and genotype relationships. Most target QTLs showed significant effects. However, significance and magnitude of QTL effects and favorable QTL allele phase varied across environments. All target QTLs showed significant QTL-by-environment interaction (QTL×E), and the QTL on chromosome 2 expressed alternative favorable QTL alleles in different environments. Digenic epistatic effects were also detected between some QTL loci. For traits such as grain yield, marker-assisted selection efforts may be better targeted at determining optimum combinations of QTL alleles rather than pyramiding alleles detected in a reference mapping population. Received: 2 June 1998 / Accepted: 17 September 1998     

A critical evaluation of a biophotothermal time scale for barley

The biophotothermal time scale for barley derived previously and based on daily maximum and minimum temperatures and photoperiod was examined and tested further. The threshold temperature of 4.3°C and the optimum of 19 or 20°C found for the planting to emergence phase, and the optimum temperature values of 18.4°C for minimum and 24.8°C for maximum for heading to soft dough were not inconsistent with the results of other authors. For some of the other cardinal points, no meaningful values were found. Tests of the biophotothermal equations with independent data indicated that they could usefully be applied under the environmental conditions prevailing on most of Canada's present or potential farmland. They gave dubious results when applied to very cool marine climates on some exposed coastal parts of Canada, and were unsatisfactory for the short-day regimes that affected early-season plantings at Buenos Aires. The equations for barley seemed much less universally applicable than those for wheat.     

Chloroplast DNA microsatellite analysis supports a polyphyletic origin for barley

Five barley chloroplast DNA microsatellites (cpSSRs) were used to study genetic relationships among a set of 186 barley accessions—34 Hordeum vulgare ssp. spontaneum (HS accessions) from Morocco, Ethiopia, Cyprus, Crete, Libya, Iraq, Iran, Turkey, Afghanistan and Israel, 122 H. vulgare ssp. vulgare landraces (HV landraces) from Spain, Bolivia (old Spanish introductions), Morocco, Libya and Ethiopia and 20 modern European spring barleys (HV cultivars). All loci were polymorphic in the material studied, with the number of alleles per locus ranging from two to three. Fifteen multi-locus haplotypes were observed, 11 in HS accessions and seven in HV landraces and cultivars. Of the seven haplotypes found in the HV lines, three were shared with the HS accessions, and four were unique. Cluster analysis revealed two main groups, one consisting of HS accessions from Ethiopia and the HV landraces from Spain, Bolivia (old Spanish), Morocco and Ethiopia, whereas the other larger group contained all of the other accessions studied. Based on these grouping and the existence of haplotypes found in the HV landraces and cultivars but not in the HS wild barley, a polyphyletic origin is proposed for barley, with further centres of origin in Ethiopia and the Western Mediterranean.     

A cDNA clone for a pathogenesis-related protein 1 from barley

A barley cDNA clone (PRb-1) corresponding to an mRNA differentially induced in resistant compared to susceptible barley cultivars by powdery mildew infection was isolated and characterised. The deduced amino acid sequence revealed 24 amino acids comprising the signal peptide and 140 amino acids of the mature peptide (15 kDa). This showed close homology to PR-1-like proteins, which have been isolated from maize, tobacco, tomato and Arabidopsis thaliana. Northern blot analysis showed accumulation of the corresponding mRNA 12 h after inoculation of resistant barley cultivars with Erysiphe graminis. Increased expression of the PRb-1 gene was also observed in resistant compared with near-isogenic susceptible barley plants following treatment with ethylene, salicylic acid, methyl jasmonate and 2,6-dichloro-isonicotinic acid.     

Major QTL for Fusarium crown rot resistance in a barley landrace

Fusarium crown rot (FCR) is a serious cereal disease in semi-arid regions worldwide. In assisting the effort of breeding cultivars with enhanced resistance, we identified several barley genotypes with high levels of FCR resistance. One of these genotypes, AWCS079 which is a barley landrace originating from Japan, was investigated by developing and assessing three populations of recombinant inbred lines. Two QTL, one located on the long arm of chromosome 1H (designated as Qcrs.cpi-1H) and the other on 3HL (designated as Qcrs.cpi-3H), were found to be responsible for the FCR resistance of this genotype. Qcrs.cpi-1H is novel as no other FCR loci have been reported on this chromosome arm. Qcrs.cpi-3H co-located with a reduced height (Rht) locus and the effectiveness of the former was significantly affected by the latter. The total phenotypic variance explained by these two QTL was over 60 %. Significant effects were detected for each of the QTL in each of the three populations assessed. The existence of these loci with major effects should not only facilitate breeding and exploitation of FCR-resistant barley cultivars but also their further characterization based on fine mapping and map-based gene cloning.     

Evidence for a light-harvesting chlorophyll a-protein complex in a chlorophyll b-less barley mutant

Chloroplasts of a chlorophyll (Chl) b-less barley mutant were solubilized with digitonin and fractionated by polyacrylamide gel electrophoresis with sodium deoxycholate in the running buffer. By this procedure, in contrast to using sodium dodecylsulfate (SDS) for solubilization, a Chl a-protein analogous to the major light-harvesting Chl a-b protein complex from wildtype chloroplasts was recovered. This mutant Chl a-protein comprises about fifty percent of the total Chl a, and is very similar in carotenoid, amino acid, protein and polypeptide composition to the major wildtype antenna Chl a-b protein. The only major differences we have found is its instability in the presence of SDS and sensitivity to protease action. Even with deoxycholate, the mutant Chl a complex often dissociates during electrophoresis into two green bands. The lack of Chl b appears to affect the normal organization of Chl a and protein in such a way as to render the complex more unstable.CIW-DPB No. 917.     

Sequence-tagged-site-facilitated PCR for barley genome mapping

Summary Speed, efficiency, and safety considerations have led many genome mapping projects to evaluate polymerase chain reaction (PCR) sequence amplification as an alternative to Southern blot analysis. However, the availability of informative primer sequences can be a limiting factor in PCR-based mapping. An alternative to random amplified polymorphism detection (RAPD) is the sequence-tagged-site (STS) approach. If informative primer sequences could be derived from known sequences, then current maps, which are based on both known function and anonymous clones, might be easily converted to maps utilizing PCR technology. In this paper, four pairs of primer sequences were obtained from published sequences, and four pairs were obtained by sequencing portions of DNA clones from genomic clones derived from a random genomic library used in the North American Barley Genome Mapping Project (NABGMP). These primers were used to screen for polymorphisms in the progeny of a winter x spring and a spring x spring barley cross. Two types of polymorphisms were distinguished using these primer sets: (1) insertion/deletion events that could be read directly from agarose gels, and (2) point mutation events. The latter were identified using polyacrylamide-gel electrophoresis of PCR products following digestion with restriction endonucleases (four-base cutters). To determine whether the PCR-based polymorphisms were allelic to polymorphisms identified by the clones from which the primer sequences derived, chromosomal assignments and (when possible) co-segregation analysis was performed.     

Prospects for molecular breeding of barley

Data from UK Recommended List Trials showed that the introduction of new cultivars of spring and winter barley has maintained a significant increase in yield over time, whereas there has been no significant improvement in hot water extract, the major determinant of good malting quality, in either crop. Commercial barley breeding is based upon phenotypic selection, and the introduction of molecular breeding methods must either increase the rate of advance, or offer an improvement in the cost‐effectiveness of breeding programmes. Molecular breeding can be applied to either single gene or polygenic characters but is not widely used in commercial barley breeding, other than as a marker for resistance to the Barley Yellow Mosaic Virus complex. There are many reports of potential targets for use in molecular breeding but the few validation studies that have been carried out to date are disappointing. Results from genomics studies are likely to lead to the identification of key candidate genes, which can be associated with economically important characters through co‐location on certain chromosomal regions. Associations between candidate gene sequence haplotypes and phenotypic characteristics is expected to identify allelic combinations, which are most frequently observed in successful cultivars, that can be used in molecular breeding of barley on a commercial scale.     

Accumulation of genes for susceptibility to rust fungi for which barley is nearly a nonhost results in two barley lines with extreme multiple susceptibility

Nonhost resistance is the most common type of resistance in plants. Understanding the factors that make plants susceptible or resistant may help to achieve durably effective resistance in crop plants. Screening of 109 barley (Hordeum vulgare L.) accessions in the seedling stage indicated that barley is a complete nonhost to most of the heterologous rust fungi studied, while it showed an intermediate status with respect to Puccinia triticina, P. hordei-murini, P. hordei-secalini, P. graminis f. sp. lolii and P. coronata ff. spp. avenae and holci. Accessions that were susceptible to a heterologous rust in the seedling stage were much more or completely resistant at adult plant stage. Differential interaction between barley accessions and heterologous rust fungi was found, suggesting the existence of rust-species-specific resistance. In particular, many landrace accessions from Ethiopia and Asia, and naked-seeded accessions, tended to be susceptible to several heterologous rusts, suggesting that some resistance genes in barley are effective against more than one heterologous rust fungal species. Some barley accessions had race-specific resistance against P. hordei-murini. We accumulated genes for susceptibility to P. triticina and P. hordei-murini in two genotypes called SusPtrit and SusPmur, respectively. In the seedling stage, these accessions were as susceptible as the host species to the target rusts. They also showed unusual susceptibility to other heterologous rusts. These two lines are a valuable asset to further experimental work on the genetics of resistance to heterologous rust fungi.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00425-004-1319-1Abbreviations ff. spp Formae speciales - RIL Recombinant inbred line - DC Double cross - DC-S Progeny produced by selfing of double-cross plants     

Proline biosynthesis in a proline-accumulating barley mutant

A barley (Hordeum vulgare L.) mutant, R5201, selected for resistance to 4? mM trans-4-hydroxyproline had a 3–6 fold increase in the soluble proline content of the leaf compared with the parent cultivar, Maris Mink. The mutant converted more [U-⁴C]glutamic acid to free proline in the leaves than Maris Mink but incorporation into protein proline was similar. Incorporation of radioactivity into proline was inhibited by exogenous proline more in Maris Mink than R5201, suggesting that feedback inhibition of proline biosynthesis is relaxed, but not absent in the mutant. When [1-¹⁴C]ornithine was the precursor, both R5201 and Maris Mink incorporated similar small amounts of label into soluble and protein proline. More protein proline was formed by both genotypes from labelled glutamic acid than from labelled ornithine. There may exist two routes of proline formation, where the glutamate pathway is synthetic and the ornithine pathway is catabolic.     

Proanthocyanidins of barley and sorghum; composition as a function of maturity of barley ears

Sorghum vulgare seeds contain a proanthocyanidin polymer consisting largely of 2,3-cis procyanidin units with M?_n, 2500. Hordeum vulgare ears contain low levels of proanthocyanidin oligomers containing 2–4 units, and composed largely of 2,3-trans procyanidin and prodelphinidin units with catechin as the terminal unit. The concentration of the oligomers in barley ears was virtually constant throughout the 33 day growth and ripening period.     

Characterization of a transport activity for long-chain peptides in barley mesophyll vacuoles

The plant vacuole is the largest compartment in a fully expanded plant cell. While only very limited metabolic activity can be observed within the vacuole, the majority of the hydrolytic activities, including proteolytic activities reside in this organelle. Since it is assumed that protein degradation by the proteasome results in the production of peptides with a size of 3-30 amino acids, we were interested to show whether the tonoplast exhibits a transport activity, which could deliver these peptides into the vacuole for final degradation. It is shown here that isolated barley mesophyll vacuoles take up peptides of 9-27 amino acids in a strictly ATP-dependent manner. Uptake is inhibited by vanadate, but not by NH(+)(4), while GTP could partially substitute for ATP. The apparent affinity for the 9 amino acid peptide was 15 μM, suggesting that peptides are efficiently transferred to the vacuole in vivo. Inhibition experiments showed that peptides with a chain length below 10 amino acids did not compete as efficiently as longer peptides for the uptake of the 9 amino acid peptide. Our results suggest that vacuoles contain at least one peptide transporter that belongs to the ABC-type transporters, which efficiently exports long-chain peptides from the cytosol into the vacuole for final degradation.     

Total protein release from barley aleurone layers as a bioassay for gibberellins

The effect of gibberellic acid on the secretion of proteins from barley (Hordeum vulgare L.) aleurone layers has been investigated for its suitability as a gibberellin bioassay. Concentrations from 10^–4 g/ml to 100 g/ml of GA₃ resulted in the release of proportionally increasing amounts of total protein. The release of proteins is not affected by indoleacetic acid and kinetin. This method has been applied and compared with the -amylase assay for the estimation of gibberellin in extracts of tomato fruits and maize seedlings.Abbreviations GA₃ gibberellic acid - IAA indoleactic acid - K kinetin     

Models for predicting soil zinc availability for barley

Regression models are proposed for the prediction of soil zinc availability within different pH ranges. The relationship between zinc concentration in barley plants, zinc content in soils and soil pH was described using a two-dimensional diagram. Results show that the soil zinc availability is significantly affected by pH changes at pH above 6.5. Below this point, the pH effect becomes gradually less important. In the low pH range, the soil zinc availability is mainly dependent on soil zinc quantity.