Salinity tolerance of wild barley Hordeum vulgare ssp. spontaneum

Salinity tolerance of 47 wild barley genotypes and six barley cultivars was evaluated under control and salinity stress (300 mM NaCl) conditions. Shoot and root dry weight (DW), plant height, membrane stability index (MSI), relative water content, survival rate, leaf malondialdehyde (MDA) and proline contents, root and leaf Na, K, Ca and K/Na ratio, and chlorophyll a fluorescence were measured. Salinity stress caused significant increase in the MDA, proline content, Na and Ca concentrations of the roots and leaves, but resulted in a decrease in the other traits. H. spontaneum genotypes were considerably less affected by the salinity than the genotypes of H. vulgare. Plant survivability was negatively correlated with the Na concentration (r =−.66) but positively correlated with the leaf K/Na ratio (r = .67) and MSI (r = .68). Tolerance mechanisms such as ion exclusion (Na) were likely to be present in the wild barley causing K/Na homeostasis as well as the much lower root and shoot Na, resulting in the higher survival rate.     

Marker-assisted characterization of frost tolerance in barley (Hordeum vulgare L.)

Five molecular markers associated to two frost tolerance QTLs ( Fr-H1 and Fr-H2 ) were tested both on nine Turkish accessions, classified by breeders as highly frost-tolerant, and on a previously described sample of 26 barleys, winter, facultative and spring. Accessions were characterized in terms of frost tolerance under both field conditions and artificial freezing test at −12°C. The Turkish lines resulted to be equal or superior to the most tolerant European genotypes tested, showing that they can be used to improve the frost tolerance of the EU barley germplasm. The marker Hv BM5A ( Vrn-H1 and Fr-H1 ) resulted to be the best predictor for assisted selection within this germplasm, because of its high correlation between allelic variation and phenotypic traits. Only Hv CBF4 of the three Hv CBF markers tested at Fr-H2 was associated to the trait, but at lower significance than HvBM5A . The PCR-based molecular marker of Vrn-H1 can thus be used in barley breeding not only for selection of facultative and winter types, but also for fast routine selection of frost tolerant genotypes.     

Mapping quantitative trait loci for salt tolerance at germination and the seedling stage in barley (Hordeum vulgare L.)

Quantitative trait loci (QTLs) controlling salt tolerance at germination and the seedling stage in barley (Hordeum vulgare L.) were identified by interval mapping analysis using marker information from two doubled haploid (DH) populations derived from the crosses, Steptoe/Morex and Harrington/TR306. Interval mapping analysis revealed that the QTLs for salt tolerance at germination in the DH lines of Steptoe/Morex were located on chromosomes 4 (4H), 6(6H), and 7(5H), and in the DH lines of Harrington/TR306 on chromosomes 5(1H) and 7(5H). In both DH populations, the most effective QTLs were found at different loci on chromosome 7(5H). Genetic linkage between salt tolerance at germination and abscisic acid (ABA) response was found from QTL mapping. The QTLs for the most effective ABA response at germination were located very close to those for salt tolerance on chromosome 7 (5H) in both crosses. The QTLs for salt tolerance at the seedling stage were located on chromosomes 2(2H), 5(1H), 6(6H), and 7(5H) in the DH lines of Steptoe/Morex, and on chromosome 7(5H) in the DH lines of Harrington/TR 306. Their positions were different from those of QTLs controlling salt tolerance at germination, indicating that salt tolerance at germination and at the seedling stage were controlled by different loci. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cytogenetic variation in somatic tissue cultures and regenerated plants of barley (Hordeum vulgare L.)

Summary Chromosome number of morphogenic and non-morphogenic calli and regenerated plants of barley were determined. Cultures were obtained from two kinds of explants, immature embryos and seedling leaves from three cultivars, Ingrid, Dissa and Golden Promise. Callus chromosome analyses were carried out during a 12 month period in a medium containing 2 mg/l of 2,4-D. Diploid cells were predominant in all cases; although in leaf-derived cultures, retraploid cells (2n=4x=28) showed a tendency to increase as time in culture increased and after more than six months in culture, diploid cells decreased to percentages of almost 70%. Aneuploid cells were generally infrequent in all cases. The source of explant has been more important than the genotype (cultivar) and the type of callus (morphogenic vs. non-morphogenic) in the chromosomal stability of cultures as time increases. From short term cultures, only 1.85% of the regenerated plants were tetraploid, the remaining were diploids. The ability of morphogenic calli to regenerate plants decreased before any significant reduction of diploid cells were observed.     

Adaptation of barley (Hordeum vulgare L.) to harsh Mediterranean environments

Summary Differences in development of the apex may be the reason for cultivar differences in adaptation of barley to terminal drought in Mediterranean environments. The present study was conducted to identify apical development patterns of barley adapted to terminal drought stressed Mediterranean environments and to determine plant characteristics which can be used as criteria to select for an adapted development. Thirty-five two-rowed barley (Hordeum vulgare L.) entries were grown at two sites in northern Syria (Tel Hadya and Breda) in 1988/89. Four apical development patterns were observed: a slow or fast vegetative development, depending on the vernalization requirement, combined with a slow or fast generative development, depending on the daylength response of the crop. Early heading was related to fast generative development. Leaf appearance rates on the main shoot were constant during a major part of the pre-anthesis period, but significant differences were observed among development patterns. Genotypic differences in main shoot tiller number were associated with differences in the onset of tiller appearance and not with differences in tiller appearance rate or final leaf number on the main shoot. Since vernalization requirements and daylength responses are largely independent of terminal drought stress, selection for an adapted phenology can be done in favourable environments. Morphological traits related to these responses (winter growth habit, cold tolerance, plant colour, growth vigour, heading date) can be used as criteria for selection for adaptation to low-rainfall Mediterranean environments.     

The grain yield of uniculm barley (Hordeum vulgare L.) in two contrasting environments

Summary Four six-rowed uniculm lines of spring barley were grown in two yield trials at different sowing densities. One trial was grown on light sandy soil in 1990. The second trial was grown on clay soil in 1991 and included the two-rowed, tillering cultivar Golf. In the trial on sandy soil, the grain yield of the uniculm lines approached that of Golf grown in an adjacent trial, but in 1991 when the growing conditions were more favourable, Golf yielded significantly more than the uniculm lines. Uniculm lines apparently perform relatively better under marginal growing conditions than in high yielding environments.The uniculm lines do not conform to the ideotype proposed for wheat by Donald (1968) but the results show that a drastic change in plant type need not to imply a large drop in grain yield.     

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     

Conservation of diversity in bulk populations of barley (hordeum vulgare L.)

Summary A series of experiments was conducted to investigate the effectiveness of mass propagated heterogeneous populations (bulk populations) in preserving genetic and phenotypic diversity. Five genetically broad-based bulk populations of cultivated barley (Hordeum vulgare L.) were employed. All of them were produced originally through mass hybridization that was facilitated by male sterility. Four of these populations had a common origin, but were subsequently propagated in different North American locations. Comparisons between early and advanced generations of these bulk populations revealed loss of variability in all populations for morphological and agronomic characters and very little to none for eight isozyme characters. Populations propagated in different locations differed in levels of residual diversity. The bulk populations were less variable than a random sample of parental accessions. The rapid loss of diversity in bulk populations was considered detrimental to genetic conservation.     

Inheritance of resistance to Rhynchosporium secalis in spring barley (Hordeum vulgare L.)

The inheritance of durable resistance of selected spring barley varieties to Rhynchosporium secalis was investigated. Data from the F₂ generation of a 4 × 4 diallel, without reciprocals and the F₄ generation of three crosses selected out of this diallel, suggest that resistance in this sample of varieties tested is complex in inheritance. Significant additive effects were detected indicating that the resistance level of barley cultivars may be improved by the hybridisation of suitable varieties. However, the genes conferring resistance seem to be concealed by the expression of one completely dominant resistance gene in our set of varieties. These results are partly in conflict with previous results on the inheritance of resistance to R. secalis in the breeder's line ‘11258/2286₁₃A’ indicating that the effectiveness of this resistance gene may be greatly influenced by the genetic background of the current population of R. secalis.     

The effect of anther orientation on microspore-derived plant production in barley (Hordeum vulgare L.)

Summary The effect of anther orientation on culture response has been examined in a range of barley cultivars of agronomic importance. Anther orientation did not significantly affect the percentage of anthers responding. However, orientation of the anthers in the up position with one lobe in contact with the medium significantly increased the number of green plants produced when compared to anthers cultured in the flat position. Green plantlet production was observed directly from embryoids i.e. without an intermediate callus phase. Cytological examination of the regenerants indicated that the majority of the plantlets possessed the normal barley karyotype. The implications of these results for Barley breeding are discussed.     

西藏青稞冬春性鉴定及抽穗期多样性与稳定性分析

为提高青稞种质资源的利用效率并筛选优异杂交亲本,分别在西藏林芝和拉萨两地的春播和秋播环境下对1605份青稞种质资源进行冬春性鉴定和抽穗期多样性分析。设拉萨春播2个播期,即正常春播I和晚10 d春播II,以2个播期的抽穗期变化作为冬春性区别依据。结果表明,96.2%的西藏青稞地方品种为春性,在西藏3个生态区均有分布,冬性品种仅有3.8%,且主要分布在以林芝为主的藏东南生态区;抽穗期的Shannon-Wiener's多样性分析表明,春播条件下抽穗期多样性高于秋播,拉萨春播条件下抽穗期多样性最高,林芝春播次之,林芝秋播最低;在相同环境下,地方品种的多样性高于育成品种;在环境稳定性分析中, 368份春性地方品种和21份育成品种在不同环境中抽穗期较为稳定,其中康青3号在两地所有参试品种中抽穗期稳定性最高。本研究为全面理解西藏青稞资源的冬春性、抽穗期多样性和环境稳定性提供了参考,为广适应性青稞品种培育筛选出环境稳定性佳的亲本材料。     

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.     

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.     

The influence of genotype and environment on seed and embryo development in barley (Hordeum vulgare L.) after crossing with Hordeum bulbosum L.

Summary Seed and embryo development was studied in crosses between H. bulbosum and the barley genotypes VK 16032, Vada and Vogelsanger Gold and subsequently the F₁ and F₂ progenies from VK 16032 x Vada and VK 16032 x Vogelsanger Gold. Both seed and embryo development are strongly influenced by the barley genotype. Favourable environmental conditions can promote seed and embryo development in genotypes with existing good characters. Dominant inheritance for good seed development and incomplete dominance for large embryos is evident. Linkage between small embryo size and winter habit exists in Vogelsanger Gold.     

Proof of concept to unmask the breeding value of genetic resources of barley (Hordeum vulgare) with a hybrid strategy

Broadening the genetic base of elite breeding programmes is crucial for further breeding success. The absence of major adaption genes, however, often masks the grain yield breeding value of genetic resources. We assessed the ability of a hybrid strategy to provide unbiased performance estimates of 21 barley genetic resources. By crossing them to elite tester lines, 25 three-way hybrids were produced and evaluated together with a part of their parents and eight elite hybrids for important agronomic traits in replicated field trials in four environments. The phenotypic data analyses revealed that the hybrid strategy facilitated to identify promising resources by substantially improving lodging resistance. Combining genotypic data for 5,562 SNPs with the phenotypic data highlighted the potential to boost the diversity of the elite breeding pool via targeted introgression of genetic resources into the male and female heterotic pools. We propose an application of the hybrid strategy for genetic resources of entire genebank collections and to use genome-wide predictions to support a targeted choice of accessions with high value for barley breeding.     

Detection of QTLs for salt tolerance in Asian barley (Hordeum vulgare L.) by association analysis with SNP markers

Two hundred ninety-six Asian barley (Hordeum vulgare L.) accessions were assessed to detect QTLs underlying salt tolerance by association analysis using a 384 single nucleotide polymorphism (SNP) marker system. The experiment was laid out at the seedling stage in a hydroponic solution under control and 250 mM NaCl solution with three replications of four plants each. Salt tolerance was assessed by leaf injury score (LIS) and salt tolerance indices (STIs) of the number of leaves (NL), shoot length (SL), root length (RL), shoot dry weight (SDW) and root dry weight (RDW). LIS was scored from 1 to 5 according to the severity of necrosis and chlorosis observed on leaves. There was a wide variation in salt tolerance among Asian barley accessions. LIS and STI (SDW) were the most suitable traits for screening salt tolerance. Association was estimated between markers and traits to detect QTLs for LIS and STI (SDW). Seven significant QTLs were located on chromosomes 1H (2 QTLs), 2H (2 QTLs), 3H (1 QTL), 4H (1 QTL) and 5H (1 QTL). Five QTLs were associated with LIS and 2 QTLs with STI (SDW). Two QTLs associated with LIS were newly identified on chromosomes 3H and 4H.     

大麦蛋白质二硫键异构酶基因家族的鉴定与表达分析

蛋白质二硫键异构酶(protein disulfide isomerases,PDIs)是定位于真核生物内质网中的一类蛋白,具有催化蛋白质二硫键氧化还原反应与协助蛋白质发生构型变化、类似分子伴侣的功能,参与生长发育、生物或非生物胁迫应答等方面的调控。真核生物中PDI基因家族的分子鉴定已有报道,但是对大麦PDI基因家族的鉴定分析鲜有报道。本研究利用生物信息学分析手段鉴定了10个大麦PDI-Like基因(HvPDILs),并分析了相应编码蛋白的结构特征。与其他物种PDILs的系统发育分析发现,10个大麦PDILs分处在8个不同的系统分支,与小麦PDILs高度同源。对公共数据库中的组织和时空表达数据分析发现, HvPDILs基因均表达,且具组织和时空表达特异性。对接种大麦温性花叶病毒(BaMMV)之后的叶片样品进行基因表达水平分析,发现其中5个HvPDILs基因出现显著的表达差异,说明其参与病毒感染过程,但参与方式及作用机制还有待后续研究。     

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.