Improved waterlogging tolerance of barley (Hordeum vulgare) by pretreatment with ethephon

ABSTRACT

Root growth into hypoxic or anoxic waterlogged soil relies on internal aeration in plants. The plant hormone ethylene helps adapt to waterlogging by inducing the formation of aerenchyma, which provides a low-resistance pathway for the transport of oxygen from the shoot to the root apex. Waterlogging-susceptible crops including barley start to form aerenchyma after suffering waterlogging stress. But waterlogging can be fatal if aerenchyma formation is not fast enough. Here, we investigated whether pre-treating barley with ethephon, an ethylene-releasing agrochemical, could improve its tolerance to mimicked waterlogging conditions (using stagnant deoxygenated agar nutrient solution). In barley growing in aerated nutrient solution, ethephon treatment enhanced aerenchyma formation at the root tips and induced the development of shorter and shallower roots. Pre-treating barley leaves also delayed waterlogging-caused whiting and increased the percentages of viable root-tips under waterlogging conditions. However, the pretreatment did not noticeably increase fresh weight or shoot length. Further studies are needed to optimize ethephon treatment conditions to improve barley production under waterlogged conditions.     

Fine-mapping and characterisation of genes on barley(Hordeum vulgare)chromosome 2H for salinity stress tolerance during germination

Salinity causes a detrimental impact on plant growth,particularly when the stress occurs during germination and early development stages.Barley is one of the most salt-tolerant crops;previously we mapped two quantitative trait loci(QTL) for salinity tolerance during germination on the short arm of chromosome 2 H using a CM72/Gairdner doubled haploid(DH) population.Here,we narrowed down the major QTL to a region of 0.341 or 0.439 Mb containing 9 or 24 candidate genes belonging to 6 or 20 function...     

Increased yield stability of field-grown winter barley (Hordeum vulgare L.) varietal mixtures through ecological processes

Crop variety mixtures have the potential to increase yield stability in highly variable and unpredictable environments, yet knowledge of the specific mechanisms underlying enhanced yield stability has been limited. Ecological processes in genetically diverse crops were investigated by conducting field trials with winter barley varieties (Hordeum vulgare), grown as monocultures or as three-way mixtures in fungicide treated and untreated plots at three sites. Mixtures achieved yields comparable to the best performing monocultures whilst enhancing yield stability despite being subject to multiple predicted and unpredicted abiotic and biotic stresses including brown rust (Puccinia hordei) and lodging. There was compensation through competitive release because the most competitive variety overyielded in mixtures thereby compensating for less competitive varieties. Facilitation was also identified as an important ecological process within mixtures by reducing lodging. This study indicates that crop varietal mixtures have the capacity to stabilise productivity even when environmental conditions and stresses are not predicted in advance. Varietal mixtures provide a means of increasing crop genetic diversity without the need for extensive breeding efforts. They may confer enhanced resilience to environmental stresses and thus be a desirable component of future cropping systems for sustainable arable farming.     

Influence of growth temperature on content,viscosity and relative molecular weight of water-soluble β-glucans in barley (Hordeum vulgare L.)

β-Glucan content and viscosity of water-soluble β-glucans have a considerable impact on the digestion of barley. Eight different 2-row barley (Hordeum vulgare L.) cultivars were grown in controlled environment chambers at five different temperatures until maturity. The samples were pearled, milled and analysed for their content of total, insoluble and soluble β-glucan. The water-soluble fraction was extracted at 37 °C, subjected to amylase treatment and freeze-dried. Water-soluble crude β-glucans were solubilised in distilled water, analysed for viscosity and their purity was checked by nuclear magnetic resonance. Molecular weights were profiled by size exclusion chromatography with RI detection. The content of total β-glucan varied from 4.0% to 7.4%, and was significantly affected by the growth temperature. An interaction between cultivar and growth temperature was observed for the total β-glucan content. The extractability was significantly affected by growth temperature, as there was recorded an increasing amount of water-soluble β-glucan with increasing growth temperature. Both the viscosity and the molecular weight of the water-soluble β-glucans increased with the growth temperature.     

Preferences of lambs offered Italian ryegrass (Lolium multiflorum L.) and barley (Hordeum vulgare L.) herbage as choices

Partial preference for feeds in ruminants is a well-documented phenomenon although their explanation can be elusive. The hypothesis was tested that sheep offered herbage of two annual grass species differing in chemical composition free-choice would select a diet that would maximize the nutritive value of the diet compared with sheep offered each herbage separately through a greater nutrient balance and synchronization of nutrient release for efficient ruminal microbial function. Fifteen male lambs were placed into metabolic cages, and randomly assigned to three treatments ( n  = 5): Italian ryegrass fresh herbage (treatment R), barley fresh herbage (treatment B) or free-choice Italian ryegrass and barley fresh herbage (treatment RB). Both herbages had similar crude protein concentrations but Italian ryegrass herbage had higher concentration of water-soluble carbohydrates and lower concentration of fibre than barley herbage. Lambs were exposed to the treatments for 15 d. Lambs on treatment RB showed a partial preference of 0·82 (s.e. 0·031) for Italian ryegrass. Lambs on treatment RB had higher intakes of digestible dry matter and higher values for nitrogen retention than lambs on treatment B although similar to that of lambs on treatment R. The results for the dietary choices were not always consistent with maximizing the nutritive value of the diet. Other explanations, such as lambs needed to sample and track the nutritive value of dietary options or there was the development of transient food aversions, were also possible.     

iTRAQ-based quantitative proteomics analysis reveals the molecular mechanism of controlled atmosphere storage for Tibetan hull-less barley (Hordeum vulgare L) preservation

Controlled atmosphere storage (CAS) is an effective method for cereal grain preservation, but its mechanism is yet to be completely elucidated. In this study, the molecular mechanism of CAS was evaluated for Tibetan hull-less barley preservation using iTRAQ quantitative proteomics, Western blot, and physicochemical and individual volatiles analyses. In barley stored at 25 °C, compared with non-controlled atmosphere storage (NCAS), CAS altered the expression of 116 proteins by > 2.0 fold. Among these proteins, 82 downregulated proteins were mainly involved in carbon metabolism, protein and amino acid metabolism, and lipid and fatty acid degradation. Physicochemical analyses suggest that CAS could reduce the severity of abiotic stress. Bioinformatic and molecular biology analyses reveal that CAS could decrease the rates of carbon metabolism, protein and amino acid metabolism, and lipid and fatty acid degradation by downregulating some key proteins (Beta-amylase, 6-phosphofructokinase 1, isocitrate dehydrogenase, glutamate decarboxylase, 1-pyrroline-5-carboxylate dehydrogenase, seryl-tRNA synthetase, leucyl-tRNA synthetase, aspartyl-tRNA synthetase, aldehyde dehydrogenase (NAD+), and alcohol dehydrogenase), accompanied by significant reductions in oxidative dehydrogenation reactions (p < 0.05). Together, a favorable environment provided by CAS ultimately mitigated physiological abnormalities, nutrient and energy consumption, and flavor deterioration in the barley. The proteomics analysis results were confirmed by Western blot, and physicochemical and individual volatiles analyses.     

Candidate genes underlying QTL for flowering time and their interactions in a wide spring barley (Hordeum vulgare L.) cross

Response to vernalization and photoperiod are the main determinants controlling the time to flowering in temperate cereals. While the individual genes that dete...     

Influence of sulphur application on hordein composition and malting quality of barley (Hordeum vulgare L.) in northern European growing conditions

The influence of sulphur (S) application on yield formation, hordein composition and malting quality of 2-rowed spring barley (Hordeum vulgare L.) was studied in Nordic conditions for the first time. In a greenhouse experiment, S deficiency was indicated when 10 mg S/kg soil or less was available, by an increase in the malate:sulphate ratio in leaves. The contents of aspartic acid and cystine in grains increased and decreased, respectively. Also a substantial decrease of total hordein and the proportion of B hordein, and an increase in the proportion of C hordein were associated with S deficiency. The effect of S was further assessed in field experiments by applying N and S in four different combinations prior to sowing. No apparent S deficiency occurred in the field conditions based on the malate:sulphate and grain N:S ratio. However, in a site where the grain S content was slightly but significantly increased by S application, a change in hordein composition and malting quality was observed. Thus even in S-sufficient conditions, the end use quality of malting barley may be affected by S application.     

转基因大麦中gfp基因的遗传及表达研究

为了探索转基因遗传及染色体重组对转基因表达的影响,以4个转绿色荧光蛋白基因(gfp)大麦系与野生型大麦相互杂交,通过对F<,2根尖和花粉细胞中绿色荧光蛋白(GFP)的检测,研究了转基因的遗传方式和表达.结果表明,绿色荧光蛋白基因在单位点和双位点插入的转基因系与野生型大麦杂交的F<,2群体中分别表现3:1和15:1的遗传分离,符合孟德尔式遗传,并表现基因的剂量效应;不同转基因系问相互杂交后代同样表现孟德尔式遗传,并出现转基因gfP表达水平提高的个体;转基因沉默系参与的杂交后代继续表现其转基因沉默.     

Genome wide association studies (GWAS) of element contents in grain with a special focus on zinc and iron in a world collection of barley (Hordeum vulgare L.)

Genome wide association studies (GWAS) were carried out to map Quantitative Trait Loci (QTL) associated with element contents in the grain using 336 spring barley. Of the elements analyzed, Fe content ranged from 21.9 to 91.0 mg kg⁻¹, Zn from 10.4 to 54.5 mg kg⁻¹, Ba from 0.2 to 8.9, Ca from 186.4 to 977.5, Cu from 1.5 to 9.8, K from 353.2 to 7721.5, Mg from 1049.8 to 2024.2, Mn from 8.1 to 22.9, Na from 55.9 to 627.9, P from 2272.9 to 5428.8, S from 880.7 to 1898.0, Si from 19.1 to 663.2, and Sr from 0.35 to 2.62 mg kg⁻¹. GWAS were carried out using 6519 SNP markers and multiple elements in MLM:PCA + K model in TASSEL software. Population analyses showed two sub-populations, primarily based on row types. GWAS for row types showed association with INTERMEDIUM-C, a modifier gene for lateral spikelet fertility in the 4H chromosome, validating current GWAS approach. GWAS also showed that 2 QTL for Ba, 2 for Ca, 4 for Cu, 11 for Fe, 2 for K, 3 for Mg, 6 for Mn, 4 for Na, 3 for S, 5 for Si, and 3 for Zn were mapped in barley chromosomes. The QTL identified in the current study are valuable for breeding nutrient dense barley cultivars in the future, especially Zn and Fe.     

转基因大麦的gfp基因表达及染色体定位

为了深入探讨转基因的整合位置对基因表达的影响，对转绿色荧光蛋白基因（gfp）大麦的荧光表达和gfp基因的染色体位置进行了研究。结果表明，绿色荧光蛋白（gfp）在大麦的根尖和花粉中均有表达，四倍体的荧光表达强度大于二倍体，表现出基因的剂量效应。gfp基因插入到第6染色体（6H）短臂和另一染色体的短臂近末端。     

Heritabilities,gains from selection and genetic correlations for grain yield of barley grown in two contrasting environments

Heritabilities and variance component estimates were obtained from a set of 15 barley lines and cultivars grown for three consecutive years in two contrasting environments in the high plateaux of Eastern Algeria. Genotype × environment interactions, particularly related to seasonal effects, seriously limited selection for increased barley grain yield. Their effect was to reduce the genetic variance component, heritability estimates and genetic correlation coefficients.The results indicated that selection in a high-yielding location does not identify genotypes suitable for low-yielding environments, which are more representative of the production conditions of a low-input agriculture. Selection in low-yielding environments appears more efficient.     

Characterization of Rsg2.a3: A new greenbug resistance allele at the Rsg2 locus from wild barley(Hordeum vulgare ssp. spontaneum)

Greenbug(Schizaphis graminum Rondani) is a destructive insect pest that not only damages plants, but also serves as a vector for many viruses. Host plant resistance is the preferred strategy for managing greenbug. Two greenbug resistance genes, Rsg1 and Rsg2, have been reported in barley. To breed cultivars with effective resistance against various greenbug biotypes, additional resistance genes are urgently needed to sustain barley production. Wild barley accession WBDC053(PI 681777) was previou...     

基于醇溶蛋白的20份大麦种质资源遗传完整性分析

为了给大麦种质的保存和更新提供依据,采用醇溶蛋白电泳技术对20份大麦种质(每一份种质各有两个繁殖年份不同的供试材料)进行了遗传完整性分析.结果表明,有5份种质是具有一种醇溶蛋白谱带带型的同质性种质,15份是具有2～6种醇溶蛋白谱带带型的异质性种质;同质性品种不同繁殖年份之间的谱带带型没有变化,而在15份异质性种质中有4份的带型数量及频率则发生了变化.说明某些大麦异质性种质在繁殖更新过程中发生了遗传完整性变化.进一步分析表明,更新发芽率水平不是影响带型频率发生显著变化的主要因素,其遗传完整性变化可能是更新发芽率水平、繁殖群体、授粉和收获方式等综合因素的影响结果.     

Evaluation of physiological traits as indirect selection criteria for drought tolerance in sugar beet

Drought is the most important limitation to sugar beet (Beta vulgaris L.) production in the UK and other areas dependent on usually insufficient summer rainfall. As increased irrigation is not a viable answer to the problem, an economically and environmentally desirable solution is new varieties with decreased sensitivity to water deficits. However, there is little genotypic information on drought tolerance in sugar beet, and breeders are not equipped to make these selections. The objectives of this study were to assess the degree of genotypic diversity for drought-related morpho-physiological traits and to measure the strength of association between these traits and indicators of crop performance. 46 sugar beet genotypes with diverse genetic backgrounds were tested in three field experiments from 1999 to 2001. Drought was imposed by covering plots with large polythene tunnels, allowing the crop to grow solely on stored soil moisture. Agronomic characters and drought tolerance indices are described in a companion paper [Ober et al., Assessing the genetic resources to improve drought tolerance in sugar beet. Agronomic traits of diverse genotypes under droughted and irrigated conditions. Field Crops Res., in press]. In this report, we show that there were significant genotypic differences for stomatal conductance, succulence index, specific leaf weight, and osmotic adjustment, but not for photosynthetic rate, relative water content or total water use. Patterns of water use within the soil profile differed between genotypes; some extracted more water from deep soil layers. The maintenance of green foliage cover during drought was positively correlated with drought tolerance index, which was negatively correlated with succulence index and scores for wilting and leaf senescence. Droughted sugar yield was positively correlated with soil water extraction and negatively correlated with relative leaf expansion rate measured in late summer. Under irrigated conditions, there was high positive correlation between transpiration rate and sugar yield. Genotype × trait biplots showed superior genotypes with relatively greater expression of combinations of favourable traits. The results suggest that succulence index and wilting score could be used to cull inferior plants in early stages of breeding programs, and green foliage cover and patterns of water use could help identify superior genotypes in elite germplasm. These data should enable tools to be developed for indirect selection of genotypes suited to drought-prone environments.     

烯效唑(S3307)对大麦整株水平Na 、K 选择性和游离脯氨酸分配的影响

为给植物生长调节荆烯效唑(S3307)的推广应用提供理论基础,以大麦为试验材料,通过喷施S3307和盆栽的方法,探讨了$3307对植物抗盐性及植株水平上Na 、K 选择性和游离脯氨酸分配的调控效应.结果表明,喷施S3307后大麦根系的Na 、K 选择性吸收能力和运输能力并未提高,由茎向叶鞘、由叶鞘向叶片、由茎向穗的Na 、K 选择性运输能力也均未得到提高;然而,喷施S3307却大幅度地提高了大麦地上部分,特别是重要光舍器官中的游离脯氨酸含量,从而增强了其对盐胁迫的抵御能力.     

NADPH Oxidases Act as Key Enzyme on Germination and Seedling Growth in Barley (Hordeum vulgare L.)

Reactive oxygen species (ROS) play an important role in seed germination. Although hydrogen peroxide (H₂O₂), a type of ROS, enhances the germination rate of various plant seeds, little is known about the mechanism. NADPH oxidases catalyze the production of superoxide anion (O₂^-) that is one of the ROS and the enzymes regulate plant development. We, therefore, investigated the role of NADPH oxidases in seed germination and seedling growth in barley (Hordeum vulgare L.). The production of O₂^- was observed both in embryo and aleurone layers in barley seeds treated with distilled water (DW). However, it was suppressed in seeds treated with diphenylene iodonium (DPI) chloride, NADPH oxidase inhibitor. Moreover, DPI markedly delayed germination and remarkably suppressed α-amylase activity in barley seeds, indicating the importance of NADPH oxidases in germination of barley seeds. The gene expression and the enzyme activity of NADPH oxidases gradually increased after imbibition, and the enzyme activities were closely correlated with seedling growth after imbibition. Besides, DPI markedly suppressed the seedling growth. These results indicated that NADPH oxidases perform a crucial function in germination and seedling growth in barley. These facts clearly reveal that O₂^- produced by NADPH oxidases after imbibition regulates seed germination and seedling growth in barley.     

Control of broadleaf weeds with post-emergence herbicides in four barley (Hordeum spp.) cultivars

Limited information is available on control of broadleaf weeds in barley and response of barley cultivars to herbicides. Field experiments were conducted from 2007 to 2009 to evaluate post-emergence herbicides for control of broadleaf weeds in four barley cultivars. Herbicide treatments included 2,4-D sodium salt at 500 g ai ha⁻¹, carfentrazone-ethyl at three rates (15, 20 and 25 g ai ha⁻¹), and metsulfuron-methyl at 4 and 5 g ai ha⁻¹. The results suggested that density of broadleaf weeds was not affected by barley cultivars in 2007 and 2008, but it was influenced in 2009. Application of carfentrazone-ethyl or metsulfuron-methyl at all the rates was effective to reduce density and biomass of broadleaf weeds in all the years. A variable response was observed for yield attributes among barley cultivars. Barley grain yield was similar in all barley cultivars in 2007; however, higher yield was recorded in ‘DWRUB 52’ in 2008 and 2009 compared to other cultivars. All herbicide treatments were usually effective to secure higher barley yields in all the years and there was a significant interaction between barley cultivars and weed management treatments. Hand hoeing was not as effective as herbicide treatments to reduce density and biomass of broadleaf weeds; however, barley yield was usually comparable with herbicide treatments. Results also revealed that there was no significant herbicide injury on any barley cultivar during three year experiments. It is concluded that carfentrazone-ethyl and metsulfuron-methyl are additional tools for broadleaf weed control in barley. However, more research is required to evaluate efficacy of these herbicides as a tank mix partner that may increase weed control spectrum in barley.     

Land suitability evaluation in damghan plain for barley, using compare and conformity methods (northeast-Iran)

In this study, land suitability evaluation based on FAO guidelines on the land evaluation system has been determined for barley irrigated area of about 3400 ha in the south of plains Damghan. In order to have more reliable soil data, particularity to control the old soil map of the area, a new soil survey was carried out in the area. South soils of Damghan plain were classified based on semi detailed studies of three physiogrphy units, four map units and two order Aridisols and Entisols. Climatic Data were used from Damghan meteorological synoptic stations for climate evaluation for barley. With respect to climate and soil severe limitations in the study area, the results of map units as the assessment methods include the storie, square root and the number of simple constraints were the same as N2 with permanent unsuitable.     

Response of Hordeum distichon cv. Igri (2-row) and H. hexastichon cv. Plaisant (6-row) winter barley to foliar applications of chlormequat

Two-row (cv. Igri) and six-row (cv. Plaisant) winter barley cultivars were incorporated into a field trial at Sutton Bonington (1984–1985) where the effects of chlormequat (CCC) applied at the three-leaf stage (main stem) and the onset of stem elongation were compared. CCC had no influence on lodging as the area cropped with ‘Igri’ completely lodged while no lodging occurred for the cultivar ‘Plaisant’.Neither CCC treatment nor cultivar influenced the rate, duration or pattern of biomass accumulation. CCC application in either the autumn or spring increased harvest index and thus grain yield for both genotypes. Mean grain mass linearly declined as ear population was increased by CCC application, with the number of grains per ear unchanged. A parabolic response of grain yield to the number of ears was inferred and an analysis was used to determine the optimum ear density.