Identification of quantitative trait loci contributing to yield and seed quality parameters under terminal drought in barley advanced backcross lines

Drought is a major limiting factor for barley production, especially in the primary areas of its cultivation. Wild barley represents a major source of favourable alleles for increasing the genetic variation for multiple traits including resistance to both biotic and abiotic stresses. We used advanced backcross quantitative trait locus (AB-QTL) analysis of a BC3-doubled haploid population developed between the cultivated parent Brenda (Hordeum vulgare ssp. vulgare) and the wild accession HS584 (H. vulgare ssp. spontaneum) to study the contribution of wild barley in improving various agronomic and seed quality traits under post-anthesis drought. The experiment was carried out at two different locations (IPK, Gatersleben and Nordsaat, Böhnshausen) and terminal drought was imposed by withholding water or spraying with potassium iodide at 10 days after flowering under greenhouse or field conditions, respectively. QTL analysis indicated that wild barley contributed favourably to most of the traits studied under both control and drought conditions. A total of seven hot-spot QTL regions with co-localizing QTL for various traits harboured more than 80 % of the stable QTL detected in the present study. For yield and thousand-grain weight and their respective drought tolerance indices, most of the QTL were derived from Brenda. On the other hand, for traits like seed length and seed nitrogen content, all the QTL were contributed by HS584, the parent having higher trait value. A significantly reduced carbon/nitrogen (C/N) ratio in the selected contrasting inferior lines compared to superior ones suggests that C/N ratio could be a potential parameter for screening not just seed quality parameters but also grain weight performance under terminal drought.     

Identification of Hordeum spontaneum QTL alleles improving field performance of barley grown under rainfed conditions

Advanced backcross QTL (AB-QTL) analysis was deployed to identify allelic variation in wild barley (Hordeum vulgare ssp. spontaneum) of value in the improvement of grain yield and other agronomically important traits in barley (Hordeum vulgare ssp. vulgare) grown under conditions of water deficit in Mediterranean countries. A population of 123 double haploid (DH) lines obtained from BC₁F₂ plants derived from a cross between Barke (European two-row cultivar) and HOR11508 (wild barley accession) were tested in replicated field trials, under varying conditions of water availability in Italy, Morocco and Tunisia, for seven quantitative traits. Significant QTL effects at one (P 0.001) or more trial sites (P 0.01) were identified for all traits. At 42 (52%) of the 80 putative QTLs identified, the allele increasing a “traits' value” was contributed by H. spontaneum. For example, though the majority (67%) of QTL alleles increasing grain yield were contributed by H. vulgare, H. spontaneum contributed the alleles increasing grain yield at six regions on chromosomes 2H, 3H, 5H and 7H. Among them, two QTLs (associated to Bmac0093 on chromosome 2H and to Bmac0684 on chromosome 5H) were identified in all three locations and had the highest additive effects. The present study shows the validity of deploying AB-QTL analysis for identifying favourable QTL alleles from wild germplasm and indicates its potential as an enhancement strategy for the genetic improvement of cultivars better adapted to drought-prone environments.     

Synthesis of salt-soluble proteins in barley. Pulse-labeling study of grain filling in liquid-cultured detached spikes

The accumulation of salt-soluble proteins in the endosperm of developing barley (Hordeum vulgare L.) grains was examined. Detached spikes of barley were cultured at different levels of nitrogen nutrition and pulse-labeled with [¹⁴C] sucrose at specific times after anthesis. Proteins were extracted from isolated endosperms and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and crossed immunoelectrophoresis. Fluorography revealed an early, middle and late synthesis of specific proteins during grain filling. Synthesis of proteins appearing at the later stages responded to increased nitrogen nutrition. Two major components, -amylase and protein Z in particular, had a synthesis profile almost identical to that of the endosperm storage protein, hordein.Abbreviations CIE Crossed immunoelectrophoresis - SDSPAGE Sodium dodecyl sulphate polyacrylamide gel electrophoresis     

Cisgenic overexpression of cytosolic glutamine synthetase improves nitrogen utilization efficiency in barley and prevents grain protein decline under elevated CO2

Cytosolic glutamine synthetase (GS1) plays a central role in nitrogen (N) metabolism. The importance of GS1 in N remobilization during reproductive growth has been reported in cereal species but attempts to improve N utilization efficiency (NUE) by overexpressing GS1 have yielded inconsistent results. Here, we demonstrate that transformation of barley (Hordeum vulgare L.) plants using a cisgenic strategy to express an extra copy of native HvGS1‐1 lead to increased HvGS1.1 expression and GS1 enzyme activity. GS1 overexpressing lines exhibited higher grain yields and NUE than wild‐type plants when grown under three different N supplies and two levels of atmospheric CO₂. In contrast with the wild‐type, the grain protein concentration in the GS1 overexpressing lines did not decline when plants were exposed to elevated (800–900 μL/L) atmospheric CO₂. We conclude that an increase in GS1 activity obtained through cisgenic overexpression of HvGS1‐1 can improve grain yield and NUE in barley. The extra capacity for N assimilation obtained by GS1 overexpression may also provide a means to prevent declining grain protein levels under elevated atmospheric CO₂.     

Diurnal variation in leaf water potential,stomatal conductance,and irradiance of winter crop under different moisture levels

Mustard (Brassica juncea) Coss., chickpea (Cicer arietinum L. and barley (Hordeum vulgare) L. were grown under different moisture levels. Diurnal changes in leaf water potential showed lower values and higher fluctuation in mustard, chickpea and barley grown with no irrigation as compared to one supplemental irrigation. Diurnal maximum of adaxial stomatal conductance in mustard and barley was higher under one irrigation treatment. In mustard stomatal conductance of abaxial surface of leaf remained higher than adaxial surface of leaf throughout the day, whereas the reverse was true in barley. Also the leaf and soil temperature and reflectance were slightly higher in all the three crops under no irrigation.     

THE PRESENCE OF PROTEASE-DIGESTIBLE MATERIAL IN GOLGI VESICLES DURING ENDOSPERM DEVELOPMENT OF SELECTED CEREALS

The presence of dictyosomes secreting densely stained vesicles throughout endosperm protein body formation was confirmed for four cereals (rice, Oryza sativa L.; hard red winter wheat, Triticum aestivum L.; winter feed barley and spring malting barley, Hordeum vulgare L.; oats, Avena sativa L.). The contents of the Golgi vesicles and protein bodies were digested with proteases for all cereals except rice. It was found in the case of rice that OsO₄ altered the proteins in the Golgi apparatus and protein bodies making them resistant to protease digestion. These results imply that the Golgi apparatus plays an important role in the concentration and transport of storage proteins into vacuoles.     

Diversity within and between populations of two sympatrically distributed Hordeum species in Jordan

Summary The diversity of two sympatrically distributed barley species (Hordeum vulgare L. and Hordeum spontaneum C. Koch.) has been assessed for 7 morphometric and 13 qualitative traits. Phenotypically, Hordeum vulgare was more stable than Hordeum spontaneum for all morphometric traits; this is a reflection of domestication and selection. The overall diversity indexes were 0.546±0.125 and 0.502±0.113 for Hordeum vulgare and Hordeum spontaneum, respectively (P=0.095). However, Hordeum spontaneum expressed a higher level of diversity for most qualitative traits. The observed similarity for a number of diversity indexes is probably due to gene flow between the two species.     

A barley RFLP map: alignment of three barley maps and comparisons to Gramineae species

Several gene linkage maps have been produced for cultivated barley. We have produced a new linkage map for barley, based on a cross between Hordeum vulgare subsp. spontaneum and Hordeum vulgare subsp. vulgare (Hvs x Hvv), having a higher level of polymorphism than most of the previous barley crosses used for RFLP mapping. Of 133 markers mapped in the Hvs x Hvv F₂ population, 69 were previously mapped on other barley maps, and 26 were mapped in rice, maize, or wheat. Two known gene clones were mapped as well as two morphological markers. The distributions of previously mapped markers were compared with their respective barley maps to align the different maps into one consensus map. The distributions of common markers among barley, wheat, rice and maize were also compared, indicating colinear linkage groups among these species.To be considered dual first authorsPublished with the approval of the Director of the Colorado State University/Agricultural Experiment Station.     

Changes in the Leaf Polypeptide Patterns of Barley Plants Exposed to Soil Flooding

Exposure of barley plants (Hordeum vulgare L.) to soil flooding for 72 – 120 h led to decrease in the content of the both subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase. The effect was more pronounced on the small subunit. Further, the changes in protein pattern were observed, mainly proteins with molecular masses 30 – 85 kD were down-regulated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Antioxidants,Enzyme Inhibitors,and Biogenic Compounds in Grain Extracts of Barleys

The content of biogenic compounds and the biological activities of barley (Hordeum vulgare L.)‐grain extracts was evaluated. The sufficiently large and heterogeneous set of barley genotypes (100 accessions) enabled the selection of special genotypes interesting for potential industrial, pharmaceutical, and medicinal applications. Barley genotypes with the highest contents of phenols, phenolic acids, flavonoids, biogenic thiols, and amines, radical‐scavenging activity, as well as inhibitory activities of trypsin, thrombin, collagenase, urokinase, and cyclooxygenase were identified.     

Two-Dimensional Electrophoretic Analysis of Salicylic Acid-Induced Changes in Polypeptide Pattern of Barley Leaves

The salicylic acid-induced changes in the polypeptide patterns of barley (Hordeum vulgare L.) leaves have been analysed using two-dimensional gel electrophoresis. An optimized 2-D PAGE protocol was used and gave reproducible 2-D gels from leaf crude protein extracts with a high number of detected polypeptides. When applied for 24 h SA affected the expression of a number of soluble proteins. Most of them appeared to be down-regulated. Although no abundant expression of specific proteins was observed, we detected three polypeptides that were present only in SA-treated leaves.     

Control of Chlorophyll Degradation in Detached Leaves of Barley and Oat through Effect of Kinetin on Chlorophyllase Levels

Chlorophyllase seems to be responsible for the degradation of chlorophyll during senescence of detached leaves of barley (Hordeum vulgare) and oat (Avena sativa). Treatment at temperatures higher than 40°C — which protects against chlorophyll loss — lowers the level of chlorophyllase. Kinetin treatment lowers the level of chlorophyllase in barley leaves and prevents its rise in oat leaves after their detachment. Synthesis of proteins in both cytoplasm and chloroplast seems to be required in order to maintain a high level of Chlorophyllase in barley leaves after detachment.     

Nickel: a micronutrient essential for higher plants

Nickel was established as an essential micronutrient for the growth of temperate cereal crops. Grain from barley (Hordeum vulgare L. cv `Onda'; containing 40 to 80 nanograms of Ni per gram dry weight) grown in solution culture with negligible Ni concentrations (< 30 nanograms of Ni per liter) exhibited greatly reduced germination rates (i.e. 50% less than grain from Ni-adequate plants) and seedling vigor of the viable grain was greatly depressed. Grain containing less than 30 nanograms per gram dry weight was inviable. Under Ni-deficient conditions, barley plants fail to produce viable grain because of a disruption of the maternal plant's normal grain-filling and maturation processes that occur following formation of the grain embryo. The observations that (a) barley plants fail to complete their life cycle in the absence of Ni and (b) addition of Ni to the growth medium completely alleviates deficiency symptoms in the maternal plants satisfies the essentiality criteria; thus, Ni should be considered a micronutrient for cereals. Because Ni is required by legumes, and is now established as essential for cereals, we conclude that Ni should be added to the list of micronutrients essential for all higher plant growth.     

Seminal roots of wild and cultivated barley differentially respond to osmotic stress in gene expression,suberization, and hydraulic conductivity

Wild barley, Hordeum vulgare spp. spontaneum, has a wider genetic diversity than its cultivated progeny, Hordeum vulgare spp. vulgare. Osmotic stress leads to a series of different responses in wild barley seminal roots, ranging from no changes in suberization to enhanced endodermal suberization of certain zones and the formation of a suberized exodermis, which was not observed in the modern cultivars studied so far. Further, as a response to osmotic stress, the hydraulic conductivity of roots was not affected in wild barley, but it was 2.5-fold reduced in cultivated barley. In both subspecies, osmotic adjustment by increasing proline concentration and decreasing osmotic potential in roots was observed. RNA-sequencing indicated that the regulation of suberin biosynthesis and water transport via aquaporins were different between wild and cultivated barley. These results indicate that wild barley uses different strategies to cope with osmotic stress compared with cultivated barley. Thus, it seems that wild barley is better adapted to cope with osmotic stress by maintaining a significantly higher hydraulic conductivity of roots during water deficit.     

DNA polymorphisms and haplotype patterns of transcription factors involved in barley endosperm development are associated with key agronomic traits

Background  

Association mapping is receiving considerable attention in plant genetics for its potential to fine map quantitative trait loci (QTL), validate candidate genes, and identify alleles of interest. In the present study association mapping in barley (Hordeum vulgare L.) is investigated by associating DNA polymorphisms with variation in grain quality traits, plant height, and flowering time to gain further understanding of gene functions involved in the control of these traits. We focused on the four loci BLZ1, BLZ2, BPBF and HvGAMYB that play a role in the regulation of B-hordein expression, the major fraction of the barley storage protein. The association was tested in a collection of 224 spring barley accessions using a two-stage mixed model approach.     

In vivo phosphorylation sites of barley tonoplast proteins identified by a phosphoproteomic approach

In plants the vacuolar functions are the cellular storage of soluble carbohydrates, organic acids, inorganic ions and toxic compounds. Transporters and channels located in the vacuolar membrane, the tonoplast, are modulated by PTMs to facilitate the optimal functioning of a large number of metabolic pathways. Here we present a phosphoproteomic approach for the identification of in vivo phosphorylation sites of tonoplast (vacuolar membrane) proteins. Highly purified tonoplast and tonoplast‐enriched microsomes were isolated from photosynthetically induced barley (Hordeum vulgare) mesophyll protoplasts. Phosphopeptides were enriched by strong cation exchange (SCX) chromatography followed either by IMAC or titanium dioxide (TiO₂) affinity chromatography and were subsequently analysed using LC‐ESI‐MS/MS. In total, 65 phosphopeptides of 27 known vacuolar membrane proteins were identified, including the two vacuolar proton pumps, aquaporins, CAX transporters, Na⁺/H⁺ antiporters as well as other known vacuolar transporters mediating the transfer of potassium, sugars, sulphate and malate. The present study provides a novel source to further analyse the regulation of tonoplast proteins by protein phosphorylations, especially as most of the identified phosphorylation sites are highly conserved between Hordeum vulgare (Hv) and Arabidopsis thaliana.     

Gene family encoding basic pathogenesis-related 1 proteins in barley

A genomic (prb1) and two cDNA clones (PRb1-2 and PRb1-3) corresponding to two new barley basic PR-1 proteins (prb1-2 and prb1-3) were isolated from Hordeum vulgare. Genomic analysis of DNA suggests that the barley genome contains at least 6 members corresponding to the gene family encoding PR-1 proteins. Expression of these genes was induced in primary leaf tissues of the H. vulgare cv. Psaknon 4^* (F14) Man. carrying Mlp resistance gene (cv. Mlp) and the near-isogenic susceptible cultivar (cv. mlp) after inoculation with Erysiphe graminis f.sp. hordei.