An Evaluation of Hordeum vulgare L. ×Psathyrostachys fragilis (Boiss.) Nevski Crosses for Doubled Haploid Barley Production

Investigations were carried out to assess the suitability of the intergeneric cross Hordeum vulgare×Psathyrostachys fragilis for haploid barley production. H. vulgare cvs. ‘Emir’ and ‘Vada’ were each pollinated with P. fragilis P.I. 343192 and plants regenerated from embryos cultured on a modified B5 medium. Seed sets on ‘Vada’ were significantly lower than on ‘Emir’, and all the planes from ‘Vada’×P. fragile remained hybrid. Several of these flowered but there was little pairing between the parental chromosomes. Most of the plants from ‘Emir’×P. fragilis died, as seedlings but 3 plants developed into haploid barley. Because of the practical limitations of pollen availability from P. fragilis and the inconsistencies in haploid plant formation, it is unlikely that the cross will prove as valuable as that between H. vulgare×H. bulbosum for a doubled haploid barley programme.     

Haploid barley from the intergeneric cross Hordeum vulgare x Psathyrostachys fragilis

Summary The intergeneric hybrid Hordeum vulgare x Psathyrostachys fragilis was fairly easily obtained. During each growing season the intermediate, perennial hybrid yielded haploid tillers of H. vulgare. Late in one season few, hybrid tillers headed. The morphology, cytology and enzymatic patterns of hybrid and haploid tillers were investigated.     

Cryopreservation of Embryogenic Callus Cultures from Barley (Hordeum vulgare L.)

Embryogenic callus cultures of barley (Hordeum vulgare L.) were frozen in the presence of a cryoprotector and subsequentjy stored in liquid nitrogen. After thawing, a high percentage of cultures resumed growth after a lag-period of 2–4 weeks. Plant regeneration was achieved at a frequency comparable to that observed in control cultures.     

Anther Culture-Derived Regenerants from Hordeum vulgare × H. bulbosum Crosses

Hordeum bulbosum has several desirable attributes, including disease resistance, which would be worthwhile transferring to H. vulgare. Despite homoeologous chromosome pairing in the interspecific hybrids, there have been few reports of successful gene introgression between the two species. A possible explanation for this is that recombinant male gametes are at a competitive disadvantage with normal balanced gametes during post-pollination events. To circumvent this problem, the possibility of obtaining plants directly from immature pollen grains was investigated. Anthers from diploid, triploid and tetraploid H. vulgare × H. bulbosum hybrids were cultured on defined media. Only hybrids with dehiscent anthers in vivo responded in culture, and after transfer of calli and embryoids to regeneration medium, 36 albino and 12 green plants were obtained. Seven of the green regenerants survived, one of which contained 15 H. vulgare chromosomes (including one acrocentric chromosome) and one H. bulbosum chromosome. Another regenerant (Ac166) resembled a diploid H. vulgare × H. bulbosum hybrid but had partial anther dehiscence and a slightly modified chromosome constitution. Mostly normal H. vulgare progeny were obtained from crosses between H. vulgare cv.‘Emir’ and Ac166, but three plants involved chromosome additions and substitutions.     

Reduced chromosome association between the short arms of 5H homologues in Hordeum vulgare L. at metaphase I

Rod or ring bivalents at metaphase I (MI) reflect whether crossing-over has occurred on one or both pairs of chromosome arms, respectively, during meiotic prophase (pachytene). In cultivated barley ( Hordeum vulgare ) the highest frequencies of rod bivalents were found for satellite chromosomes (either 5H or 6H). To distinguish between chromosome 5H and 6H associations, a recombinant line derived from an H. vulgare × H. bulbosum hybrid with a hemizygous introgression from H. bulbosum on the short arm of chromosome 6H was probed with 45S rDNA and pSc119.2 using fluorescent in situ hybridization and compared with non-recombinant H. vulgare. The frequencies of rod bivalents, caused by failure of the short arms of 5H chromosomes (5HS) to associate during meiosis in the recombinant line, were similar to the frequencies of rod bivalents involving the satellite chromosomes in H. vulgare. Hence, rod bivalent formation in H. vulgare satellite chromosomes is probably based on reduced association of 5HS, corresponding to a low frequency of genetic recombination. 5HS is, therefore, more likely to show linkage disequilibrium than the other chromosome arms.     

Effects of selection and opportunities for recombination in doubled-haploid populations of barley (Hordeum vulgare L.)

Doubled-haploid breeding systems are typically based on sampling gametes from F₁ plants. However, in the case of repulsion linkages, additional recombination could be advantageous. Pre-selection of gamete donors might also shift progeny performance in a desired direction. The objectives of this study were to quantify the effects of an additional round of recombination and assess the effectiveness of pre-anthesis selection in the production of barley doubled haploids. Assessments were conducted on: 1. 100 F₁-derived lines representing a subset of lines used in previous genome-mapping studies; 2. 100 random F₂-derived lines; and 3. 50 F₂-derived lines from gamete donors selected for early heading. An additional round of recombination had only a modest effect on generating more favourable genotypes. Pre-anthesis selection was ineffective in generating an earlier heading population. According to published quantitative-trait locus (QTL) analyses based on the F₁ -derived population, there are few repulsion linkages between QTL determining the traits measured in this experiment. Any advantages to be gained from postponing the generation of derivation of doubled haploids must be weighed against the delay and additional cost.     

Cloning, genetic and physical mapping of resistance gene analogs in barley (Hordeum vulgare L.)

The majority of verified plant disease resistance genes isolated to date belong to the NBS‐LRR class, encoding proteins with a predicted nucleotide binding site (NBS) and a leucine‐rich repeat (LRR) region. Using degenerate primers, designed from the conserved motifs of the NBS region in tobacco N and Arabidopsis RPS2 genes, we isolated 190 resistance gene analogs (RGA) clones from barley genomic DNA. A total of 13 single‐ and low‐copy RGAs were genetically mapped onto chromosomes 1H–7H (except 5H) using three barley double haploid (DH) mapping populations: Steptoe × Morex, Harrington × TR306 and LUGC × Bowman. Sequence analysis of the RGAs showed that they are members of a diverse group. As a result of BLAST searches, one RGA proved unique as it did not detect any significant hit. Another RGA is putatively functional, because it detected several barley expressed sequence tag (EST) matches. To physically map the RGAs, 13 sequences were used to screen a 6.3 × cv. ‘Morex’ bacterial artificial chromosome (BAC) library. After fingerprint analysis, eight contigs were constructed incorporating 62 BAC clones. These BAC contigs are of great value for positional cloning of disease resistance genes, because they span the regions where various barley R genes have been genetically mapped.     

Genetic analysis of heading date and other agronomic characters in barley (Hordeum vulgare L.)

Genetic analyses of heading date, tiller number, plant height, grain yield, kernel weight, and plump and thin kernels were made in three six-rowed barley crosses (Hordeum vulgare L.) involving four cultivars. Six populations, P₁ , P₂ , F₁ , F₂ , BC₁ , and BC₂ , from each cross were grown and evaluated at Fargo and Prosper, North Dakota, 1982. Parental means within crosses generally were different except for tiller number. Comparison of generation means suggested that late heading was dominant to early, high kernel weight was dominant to low, and kernel plumpness was influenced by additive gene action. The relationship between yield and heading date was not consistent among crosses and positive r values were quite low. It should be possible to select early maturing, high yielding segregates with plump kernels. Heterosis over the mid-parent was quite similar among crosses for heading date, but there was no heterosis over the high parent. Inbreeding depression was fairly constant for heading date, but was less consistent for yield. The lack of uniformity for estimates of inbreeding depression can be related to environmental variation and to its influence on type of gene action. The ratio of additive to dominance variance was inconsistent among crosses for heading date and yield. These data suggest selection for these characters should be delayed past the F 2 generation. Broad sense heritabilities for heading date ranged from 42 to 86%. Values obtained for grain yield were more consistent among broad sense than narrow sense estimates. Genetic advance estimates were low due to lack of additive variance. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Effect of Carbohydrate Composition and Concentration on Anther Culture Response in Barley (Hordeum vulgare L.)

Culture medium composition is critical for the successful induction of microspore division in vitro. The present experiments have focused on a relatively neglected area of cell and tissue culture research, namely the carbohydrate component used in the medium. Three spring barley genotypes were cultured on a medium which was modified by replacing sucrose with the following carbohydrates (6 % w/v): maltose, fructose, malt extract, galactose and a glucose (3 % w/v)/fructose (3 % w/v) mixture. Both maltose and malt extract were superior to sucrose in their capacity to induce green plantlet differentiation from microspores. The concentrations of both sucrose and maltose were also varied. Overall the response of anthers on maltose based media was higher than on sucrose based media. Furthermore, a concentration of maltose m the range 6—12 % w/v produced a higher frequency of green plants than a low concentration (1—3 % w/v). The effect of maltose based media on germplasm of direct relevance to barley breeders was also tested. The cultivar ‘Blenheim’ was shown to be very responsive and this genetic factor was transmitted to the F₁ hybrid. The frequency of haploid to diploid regenerants was not consistent over genotypes, but in general there were more haploid than diploid regenerants. The implications of these results for barley breeding are discussed.     

A skeletal linkage map of Hordeum bulbosum L. and comparative mapping with barley (H. vulgare L.)

A restriction fragment length polymorphism (RFLP) based linkage map of a cross between two diploid Hordeum bulbosum (2n = 2x = 14) clones, PB1 and PB11, was constructed from 46 recombinant progeny clones. Since both parents are heterozygous, separate and combined parental maps were constructed. All of the RFLP markers screened had previously been mapped in barley (H. vulgare L.) so that comparative maps could be produced. The PB1 linkage map consists of 20 RFLP marker loci assigned to four linkage groups covering 94.3 cM. The PB11 linkage map consists of 27 RFLP marker loci assigned to six linkage groups covering 149.1 cM. Thirteen markers polymorphic in both parents were used as ‘anchors’ to create a combined linkage map consisting of 38 loci assigned to six linkage groups and covering a genetic distance of 198 cM. Marker order was highly conserved in a comparison with the linkage map of H. vulgare (Laurie etal., 1995). However, in contrast, the genetic distances for the same markers were very different being 649 cM and 198 cM respectively, a genetic distance ratio of 1: 3.3. Thus although the map was short, it can be presumed to cover half the genome of H. bulbosum. This study provides further confirmation of the close relationship between the two species and gives a basis for the development of marker mediated introgression through interspecific hybridisation between the two species. This revised version was published online in July 2006 with corrections to the Cover Date.     

The resistance to leaf rust and powdery mildew of recombinant lines of barley (Hordeum vulgare L.) derived from H. vulgare × H. bulbosum crosses

A set of 23 recombinant lines (RLs) of barley ( Hordeum vulgare L.) derived from H. vulgare  ×  H. bulbosum L. crosses was inoculated with barley leaf rust ( Puccinia hordei ) and powdery mildew ( Blumeria graminis f.sp. hordei ) at the seedling stage to identify their levels and mechanisms of resistance. Eight RLs were studied further in glasshouse and field tests. All three barley parents ('Emir', 'Golden Promise' and 'Vada') were highly susceptible to powdery mildew and leaf rust isolates. Several RLs showed partial resistance expressed as high relative latency periods and low relative infection frequencies against leaf rust. This high level of partial resistance was due to a very high level of early aborting colonies without host cell necrosis. Several RLs showed hypersensitive resistance to some or all isolates. For powdery mildew, one RL was completely resistant to the CC1 isolate and had a hypersensitive resistance to the CO-02 isolate. Three RLs derived from 'Emir' were completely resistant to both powdery mildew isolates, and three more RLs tested in the field had higher levels of partial resistance than their parents. The results indicate that H. bulbosum contains major and minor gene(s) for resistance to leaf rust and powdery mildew that can be transferred to cultivated barley.     

The Impact of Underseeding Barley (Hordeum vulgare L.) on Timothy (Phleum pratense L.)-Clover (Trifolium pratense L.; Trifolium hybridum L.) Forage Production in a Cool Maritime Climate

Growing barley (Hordeum vulgare L.) in the year of forage establishment is a common agronomic practice in marginal growing regions, but is often not recommended to growers. We examined the effect of silage barley production over an establishing timothy (Phleum pratense L.)‐clover (Trifolium pratense L.; Trifolium hybridum L.) forage sward in a 4‐year study near St. John's, Newfoundland, Canada. The experiment compared two barley varieties differing in plant height (semidwarf Chapais and Leger), three barley seeding rates and the effect of a forage understorey on forage (barley) production in the establishment year and forage (timothy‐clover) production in the subsequent year. The taller Leger yielded similar forage biomass to Chapais in the year of forage establishment, which (when planted at 375 plants m^?2) was roughly twice that of a pure‐stand timothy‐clover mix. Increasing the barley seeding rate from 125 to 375 plants m^?2 resulted in a linear increase in forage yield in the year of planting. The production of barley forage in the establishment year resulted in reduced timothy‐clover forage yield in the year following barley planted at 125 and 375 seeds m^?2, but not for barley planted at 250 seeds m^?2. Companion planting also altered forage species composition in that higher barley seeding rates resulted in 12–18 % less timothy and 2–4 % lower fibre levels in the year following planting. Barley seeded at rates of 250–375 seeds m^?2 and undersown with a timothy‐clover mixture (harvested at mid‐milk) resulted in greater forage yield of poorer quality than pure‐stand timothy‐clover in the planting year, and a barley seeding rate of 250 seeds m^?2 did not impede forage production in the subsequent year.     

Variation in developmental patterns of wild barley (Hordeum spontaneum L.) and cultivated barley (H. vulgare L.)

Summary Six wild barley (Hordeum spontaneum) accessions, from a diverse range of habitats, and two spring-cultivated barleys, were examined for variation in durations of development phases. The durations of the leaf initiation and spikelet initiation phases were longer and spikelet growth phases shorter, in wild than in cultivated barley. Across all wild and cultivated barleys the rate and duration of spikelet initiation were negatively correlated, but neither was related to the number of spikelets per spike. The number of spikelets was positively correlated with the number of leaves and the ratio of the number of spikelets to the number of leaves declined with increasing time to anthesis, indicating that each successive leaf was associated with a diminishing increase in the number of spikelets. The duration of culm elongation and final culm length were shorter in accessions of cultivated barley compared with wild barley. This paper also discusses the feasibility for increasing the number of spikelets per spike through breeding for genetic changes in lengths of pre-anthesis phases of development.Abbreviations ANOVA Analysis of variance - HV Hordeum vulgare - CE Culm elongation - DR Double ridge - HS Hordeum spontaneu - ° Cd Degree days     

The transfer of a gene conferring resistance to scald (Rhynchosporium secalis) from Hordeum bulbosum into H. vulgare chromosome 4HS

Scald is a serious foliar disease that infects barley (Hordeum vulgare L.) causing reduced yields and adversely affecting quality. A means to combat the disease is to breed cultivars that possess genetic resistance. However, all known resistance alleles have so far originated from within the primary genepool of barley. This reliance on H. vulgare and H. vulgare ssp. spontaneum as resistance sources may encourage virulent forms of the pathogen to become established. To broaden the genetic base of cultivated barley and provide novel resistances to many diseases we have used a species from the secondary genepool of barley, H. bulbosum, in a resistance‐breeding programme. In this study we describe the development and trialling of a scald‐resistant recombinant line derived from a hybrid between H. vulgare and H. bulbosum. The scald resistance is simply inherited and located on the short arm of barley chromosome 4 (4HS).     

大麦基因组GRAS基因家族的全基因组鉴定与表达分析

GRAS基因家族是一类仅存在于植物并广泛参与其生长发育调控的转录因子,根据其序列结构和系统发育树分化特征,GRAS转录因子包含PATI,DELLA,HAM,SCR,SHR等多个亚家族成员.本研究利用大麦最新的基因组数据库,采用生物信息学的方法筛选鉴定出41条GRAS基因序列,其中有34条序列具有完整的GRAS家族蛋白特...     

Relationship between phenotypic and genetic diversity of parental genotypes and the frequency of transgression effects in barley (Hordeum vulgare L.)

The aim of the study was to evaluate the relationship between genetic and phenotypic distances of parents and the genetic potential of crosses as measured by the frequency of transgressive segregants in homozygous populations. Material for the study involved 17 barley cross‐combinations. In each cross, the parental genotypes, F₂ hybrids and doubled haploid (DH) lines were analysed. Yield and yield‐related traits were observed in the experiments. Phenotypic (univariate and multivariate) and genetic distances (GD) were investigated between pairs of parental genotypes. Genetic distance was evaluated by using random amplified polymorphic DNA markers. In F₂ generations, the genetic coefficient of variability (GCV) was evaluated. Within all the cross‐combinations studied, each DH line was compared with both parents to distinguish the positive and negative transgressive lines. In addition, the coefficient of gene distribution (r) along parental genomes was evaluated. Relationships between frequency of transgression and both phenotypic and GDs, GCV and r, were assessed by regression analysis. It was found that for all the traits studied the frequency of transgressive lines depended mainly on gene distribution (r). Genetic distance between parents appeared to be significant for the occurrence of transgression effects in plant height, ear length, grain weight per ear and grain yield per plot. Regression analysis has shown that phenotypic differences between parental genotypes were also important for the frequency of transgressive lines. A weak relationship was found between the variation of F₂ hybrids and the occurrence of transgressive lines. The results indicate that occurrence of transgressive segregants in a homozygous population should be considered as a phenomenon dependent simultaneously on several factors characterizing parental genotypes. Among them, the most important are: gene distribution, phenotypic diversity and GD.     

The influence of photoperiod on the Vrn-H2 locus (4H) which is a major determinant of plant development and reproductive fitness traits in a facultative × winter barley (Hordeum vulgare L.) mapping population

To determine the effect of Vrn‐H2 locus on plant developmental and agronomic traits, detailed controlled environment tests involving a factorial set of vernalization and photoperiod treatments were carried out using doubled haploid lines developed from a facultative (Vrn‐H2^?) × winter (Vrn‐H2⁺) barley cross. The allele phase at the Vrn‐H2 locus influenced heading date as well as the developmental and agronomic traits. The performance of Vrn‐H2⁺ lines was significantly influenced by vernalization: reproductive fitness traits showed significant decreases without vernalization. However, the effects of alleles at the Vrn‐H2 locus extended beyond simple satisfaction of the vernalization requirement. Vrn‐H2⁺ lines showed increased reproductive fitness compared with Vrn‐H2^? lines when vernalization was followed by a long photoperiod. The responses of the two Vrn‐H2 allele classes to photoperiod duration were quite different in terms of heading date, developmental and agronomic traits. These results suggest that alleles at the Vrn‐H2 locus – and/or tightly linked gene(s) – respond primarily to the exogenous signal of vernalization (temperature), but when the vernalization requirement has been fulfilled, they also respond to photoperiod duration.     

Breeding Progress in Grain Yield and Selected Agronomic Characters of Winter Barley (Hordeum vulgare L.) over the Last Quarter of a Century

This study gives estimates of breeding progress achieved in winter barley (Hordeum vulgare L.) since the 1960′s in grain yield and the change in several morphological traits for seventeen historically important cultivars: 12 six-rowed and 5 two-rowed, grouped into four epochs according to the period of major commercialization in Italy. All genotypes were evaluated across a range of soil fertility and climatic environments. The modern six-rowed cultivars have shown a consistent increase in tillers/m² and seeds/spike (16 and 28 %, respectively) over the local populations. In the modern two-rowed cultivar ‘Igri’ the increase in tillers/m² and seed weight were, respectively, 20 and 14 % snd seeds/spike decreased by 20 % over the local populations. The modern six-rowed and two-rowed cultivars have less lodging, are earlier and shorter than the old varieties and local populations. In the last quarter of a century, the breeding progress for gram yield has been increased by 52 and 74 kg/ ha/year or 0.75 and 1.1 % per year respectively, for six-rowed and two-rowed genotypes: while the gain in biomass yield in the same period was not uniform for six-rowed cuitivars and increased by 64 kg/ha/ year or 0.46 % in two-rowed cultivars. The grain yield improvement in the modern six-rowed and two-rowed cultivars is the result of a better partitioning of the photosynthetic products into the grain.     

Effect of powdery mildew (Erysiphe graminis f.sp. hordei) on photosynthesis and grain yield of partially resistant genotypes of spring barley (Hordeum vulgare L.)

The effect of powdery mildew on the photosynthesis and grain yield of partially resistant spring barley was investigated. The effect of powdery mildew on the CO₂ exchange rate (CER) of inoculated and non-inoculated leaves was measured in several glasshouse experiments. Grain yield reduction by powdery mildew was determined in three field experiments. The CER of the inoculated leaves was reduced by infection but that of the non-inoculated leaves was not significantly different from that of the corresponding leaves of the control plants. The reduction in CER of the different genotypes was closely related to the percentage leaf area infected with powdery mildew. The correlation between degree of mildew infection and grain yield reduction varied between r = 0.84 (significant at P = 0.01) and r = 0.41 (not significant). Differences in greenness of the crop were correlated better with grain yield reduction (r = 0.66, P = 0.01) than powdery-mildew infection itself. Low percentages of powdery-mildew infection did not lead to significant reduction in grain yield. Partial resistance to powdery mildew could thus be a valuable attribute of future barley varieties.     

Morphological and molecular analysis of androgenetic, selfed and backcrossed plants produced from a Hordeum vulgare x H, bulbosum hybrid

Anther culture (AC) was carried out on a fertile triploid hybrid between Hordeum vulgare L. (cultivated barley) and H. bulbosum L, (bulbous barley grass) to determine whether AC-derived regenerants differed from progeny obtained through selfing and backcrossing. Chromosome counts were carried out on all plants and DNA was extracted from them to prepare Southern blots for molecular analysis. To identify true recombinants, the blots were probed with rye repetitive sequence probes (pSc119.1 and pScl19.2). which hybridize strongly and specifically to H. bulbosum DNA. Twenty probes that detect single- or low-copy sequences were hybridized with Southern blots containing restricted DNA extracted from 25 AC-derived plants, 11 selfed and six backcrossed progeny that showed hybridizations with pScll9. Although restriction fragment length polymorphisms (RFLPs) were only observed using probes that map to four of the possible 14 chromosome arms, an introgression associated with chromosome 6HS was frequently observed among plants derived from AC. selfing and backcrossing. Plants from AC differed from selfed and backcrossed progeny in their chromosome number; unique RFLP bands that were occasionally observed may indicate chromosomal rearrangements.