Mapping QTL controlling yield and yield components in a spring barley (Hordeum vulgare L.) cross using marker regression

An RFLP map constructed from 99 doubled haploid lines of a cross between two spring barley varieties (Blenheim × Kym) was used to localize quantitative trait loci (QTL) controlling grain yield and yield components by marker regression and single-marker analysis. Trials were conducted over three years. Genotype-by-year interaction was detected for plant grain weight and ear grain weight so they were analysed separately for each year. None was detected for thousand-grain weight and ear grain number so data were pooled over years. A total of eleven QTL were detected for plant grain weight over two years and fourteen for ear grain weight over three years. Seven QTL were detected for plot yield. The locus with the largest effect was on chromosome 2(2H)L and accounted for 19% of the variation in the progeny. Eight QTL were detected for thousand-grain weight and five for ear grain number. Many of the QTL detected were in comparable positions in each year. Yield and yield components were only partly correlated. Comparisons based on common RFLP markers showed that some QTL were found in positions similar to those identified in other studies. For a number of QTL the identification of linked markers provided suitable opportunities for marker-assisted selection and improvement of barley and reference markers with which to analyse the homoeologous chromosome regions of wheat and other cereals.     

QTL analysis of tolerance to a German strain of BYDV-PAV in barley (Hordeum vulgare L.)

One hundred and forty six barley doubled-haploid lines (DH lines) were tested for variation in grain yield, yield components, plant height, and heading date after artificial infection with a German isolate of barley yellow dwarf virus (BYDV-PAV-Braunschweig). Of these 146 lines 76 were derived from the cross of the barley yellow dwarf virus (BYDV) tolerant cultivar ’Post’ to cv ’Vixen’ (Ryd2) and 70 from the cross of Post to cv ’Nixe’. Phenotypic measurements were gathered on both non-infected plants and plants artificially inoculated with BYDV-PAV by viruliferous aphids in pot and field experiments for three years at two locations. For all traits a continuous variation was observed suggesting a quantitative mode of inheritance for tolerance against BYDV-PAV. Using skeleton maps constructed using SSRs, AFLPs and RAPDs, two QTLs for relative grain yield per plant after BYDV infection, explaining about 47% of the phenotypic variance, were identified in Post × Vixen at the telomeric region of chromosome 2HL and at a region containing the Ryd2 gene on chromosome 3HL. In Post × Nixe, a QTL was found in exactly the same chromosome 2HL marker interval. In this cross, additional QTL were mapped on chromosomes 7H and 4H and together these explained about 40% of the phenotypic variance. QTL for effects of BYDV infection on yield components, plant height, and heading date generally mapped to the same marker intervals, or in the vicinity of the QTL for relative grain yield, on chromosomes 2HL and 3HL, suggesting that these regions are of special importance for tolerance to the Braunschweig isolate of BYDV-PAV. Possible applications of marker-assisted selection for BYDV tolerance based on these results are discussed. Received: 1 December 2000 / Accepted: 9 March 2001     

Significance of root hairs for plant performance under contrasting field conditions and water deficit

Background and AimsPrevious laboratory studies have suggested selection for root hair traits in future crop breeding to improve resource use efficiency and stress tolerance. However, data on the interplay between root hairs and open-field systems, under contrasting soils and climate conditions, are limited. As such, this study aims to experimentally elucidate some of the impacts that root hairs have on plant performance on a field scale.MethodsA field experiment was set up in Scotland for two consecutive years, under contrasting climate conditions and different soil textures (i.e. clay loam vs. sandy loam). Five barley (Hordeum vulgare) genotypes exhibiting variation in root hair length and density were used in the study. Root hair length, density and rhizosheath weight were measured at several growth stages, as well as shoot biomass, plant water status, shoot phosphorus (P) accumulation and grain yield.Key ResultsMeasurements of root hair density, length and its correlation with rhizosheath weight highlighted trait robustness in the field under variable environmental conditions, although significant variations were found between soil textures as the growing season progressed. Root hairs did not confer a notable advantage to barley under optimal conditions, but under soil water deficit root hairs enhanced plant water status and stress tolerance resulting in a less negative leaf water potential and lower leaf abscisic acid concentration, while promoting shoot P accumulation. Furthermore, the presence of root hairs did not decrease yield under optimal conditions, while root hairs enhanced yield stability under drought.ConclusionsSelecting for beneficial root hair traits can enhance yield stability without diminishing yield potential, overcoming the breeder’s dilemma of trying to simultaneously enhance both productivity and resilience. Therefore, the maintenance or enhancement of root hairs can represent a key trait for breeding the next generation of crops for improved drought tolerance in relation to climate change.     

Identification and characterization of novel senescence-associated genes from barley (Hordeum vulgare) primary leaves

Leaf senescence is the final developmental stage of a leaf. The progression of barley primary leaf senescence was followed by measuring the senescence-specific decrease in chlorophyll content and photosystem II efficiency. In order to isolate novel factors involved in leaf senescence, a differential display approach with mRNA populations from young and senescing primary barley leaves was applied. In this approach, 90 senescence up-regulated cDNAs were identified. Nine of these clones were, after sequence analyses, further characterized. The senescence-associated expression was confirmed by Northern analyses or quantitative RealTime-PCR. In addition, involvement of the phytohormones ethylene and abscisic acid in regulation of these nine novel senescence-induced cDNA fragments was investigated. Two cDNA clones showed homologies to genes with a putative regulatory function. Two clones possessed high homologies to barley retroelements, and five clones may be involved in degradation or transport processes. One of these genes was further analysed. It encodes an ADP ribosylation factor 1-like protein (HvARF1) and includes sequence motifs representing a myristoylation site and four typical and well conserved ARF-like protein domains. The localization of the protein was investigated by confocal laser scanning microscopy of onion epidermal cells after particle bombardment with chimeric HvARF1-GFP constructs. Possible physiological roles of these nine novel SAGs during barley leaf senescence are discussed.     

Identification of two key genes controlling chill haze stability of beer in barley (Hordeum vulgare L)

Background

In bright beer, haze formation is a serious quality problem, degrading beer quality and reducing its shelf life. The quality of barley (Hordeum vulgare L) malt, as the main raw material for beer brewing, largely affects the colloidal stability of beer.

Results

In this study, the genetic mechanism of the factors affecting beer haze stability in barley was studied. Quantitative trait loci (QTL) analysis of alcohol chill haze (ACH) in beer was carried out using a Franklin/Yerong double haploid (DH) population. One QTL, named as qACH, was detected for ACH, and it was located on the position of about 108 cM in chromosome 4H and can explain about 20 % of the phenotypic variation. Two key haze active proteins, BATI-CMb and BATI-CMd were identified by proteomics analysis. Bioinformatics analysis showed that BATI-CMb and BATI-CMd had the same position as qACH in the chromosome. It may be deduced that BATI-CMb and BATI-CMd are candidate genes for qACH, controlling colloidal stability of beer. Polymorphism comparison between Yerong and Franklin in the nucleotide and amino acid sequence of BATI-CMb and BATI-CMd detected the corresponding gene specific markers, which could be used in marker-assisted selection for malt barley breeding.

Conclusions

We identified a novel QTL, qACH controlling chill haze of beer, and two key haze active proteins, BATI-CMb and BATI-CMd. And further analysis showed that BATI-CMb and BATI-CMd might be the candidate genes associated with beer chill haze.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1683-1) contains supplementary material, which is available to authorized users.     

Growth parameters and resistance against Drechslera teres of spring barley (Hordeum vulgare L. cv. Scarlett) grown at elevated ozone and carbon dioxide concentrations

Spring barley ( Hordeum vulgare L. cv. Scarlett) was grown at two CO2 levels (400 vs. 700 ppm) combined with two ozone regimes (ambient vs. double ambient) in climate chambers for four weeks, beginning at seedling emergence. Elevated CO2 concentration significantly increased aboveground biomass, root biomass, and tiller number, whereas double ambient ozone significantly decreased these parameters. These ozone-induced reductions in growth parameters were strongly overridden by 700 ppm CO2. The elevated CO2 level increased C : N ratio of the leaf tissue and leaf starch content but decreased leaf protein levels. Exposure to double ambient ozone did not affect protein content and C : N ratio but dramatically increased leaf starch levels at 700 ppm CO2. Resistance against Drechslera teres (Sacc.) Shoemaker was increased in leaves grown at double ambient ozone but was less obvious at 700 ppm than at 400 ppm CO2. Constitutive activities of beta-1,3-glucanase and chitinase were significantly higher in leaves grown at double ambient ozone compared to ambient ozone levels. The sum of methanol-soluble and alkali-released cell wall-bound aromatic metabolites (i.e., C-glycosylflavones and several structurally unidentified metabolites) and lignin contents did not show any treatment-dependent differences.     

Nitrogen use efficiencies of spring barley grown under varying nitrogen conditions in the field and growth chamber

Background and Aims

Nitrogen-use efficiency (NUE) of cereals needs to be improved by nitrogen (N) management, traditional plant breeding methods and/or biotechnology, while maintaining or, optimally, increasing crop yields. The aims of this study were to compare spring-barley genotypes grown on different nitrogen levels in field and growth-chamber conditions to determine the effects on N uptake (NUpE) and N utilization efficiency (NUtE) and ultimately, NUE.

Methods

Morphological characteristics, seed yield and metabolite levels of 12 spring barley (Hordeum vulgare) genotypes were compared when grown at high and low nitrogen levels in field conditions during the 2007 and 2008 Canadian growing seasons, and in potted and hydroponic growth-chamber conditions. Genotypic NUpE, NUtE and NUE were calculated and compared between field and growth-chamber environments.

Key Results

Growth chamber and field tests generally showed consistent NUE characteristics. In the field, Vivar, Excel and Ponoka, showed high NUE phenotypes across years and N levels. Vivar also had high NUE in growth-chamber trials, showing NUE across complex to simplistic growth environments. With the high NUE genotypes grown at low N in the field, NUtE predominates over NUpE. N metabolism-associated amino acid levels were different between roots (elevated glutamine) and shoots (elevated glutamate and alanine) of hydroponically grown genotypes. In field trials, metabolite levels were different between Kasota grown at high N (elevated glutamine) and Kasota at low N plus Vivar at either N condition.

Conclusions

Determining which trait(s) or gene(s) to target to improve barley NUE is important and can be facilitated using simplified growth approaches to help determine the NUE phenotype of various genotypes. The genotypes studied showed similar growth and NUE characteristics across field and growth-chamber tests demonstrating that simplified, low-variable growth environments can help pinpoint genetic targets for improving spring barley NUE.     

Relative growth rates of leaves from soybean grown under drought-stressed and irrigated field conditions

Abstract. The relative growth rates and leaf area were graphed against leaf area, normalized with respect to final leaf area, to assess the applicability of the Lockhart cell wall expansion equation to soybean, Glycine max (L.) Merr., leaf development under field conditions. For leaves that had completed more than 20% of their growth, relative growth rates decreased linearly with an increase in the normalized leaf area, indicating that these leaves were undergoing strictly expansive growth. Drought stress significantly decreased the relative growth rate of these larger leaves. Small leaves which had completed less than 20% of their growth, were found to have highly variable relative growth rates. The large variability in relative growth rates indicated that the Lockhart cell wall expansion equation was inadequate to evaluate the growth of these young leaves. Drought stress had virtually no influence on the relative growth rates observed in the small leaves.     

两种肥力水平下水稻苗高QTL的比较分析

利用一个来源于粳／籼交组合的水稻重组自交系群体进行盆栽试验,设正常肥力(对照CK)和低肥力(不施肥)2个处理,分别在播种后25d(时期Ⅰ)和50d(时期Ⅱ)取样测定秧苗的苗高。结合一张含有198个标记的高密度分子遗传图谱,对性状进行复合区间作图。共检测到8个水稻苗高QTL,分别位于第1、3、5、6、8和10号染色体上,各QTL对性状的贡献率为4％～12％。通过对2种肥力水平下水稻苗高QTL的比较分析,发现大多数QTL只在1种肥力水平下表达,QTL与不同肥力水平之间存在着显著的互作。唯一一个在2种肥力水平下均能稳定起作用、而且加性效应的方向一致的QTL是qSH-3-2,该QTL位于3号染色体标记区间RM156-RM16,其加性效应值为正,增效基因来自于亲本Lemont。此外,有3个QTL(qSH-1、qSH-3-3和qSH-5)在2个抽样时期均起作用,且加性效应的方向一致。对利用分子标记辅助选择改良水稻品种的耐低肥特性的育种策略进行了讨论。     

玉米雌雄开花间隔天数、结穗率与产量的数量性状位点(QTL)分析

采用SSR标记连锁图谱和复合区间作图法在山西灌溉和干旱胁迫条件下,对玉米(Zea mays L.)自交系黄早四×掖107组合的F3群体雌雄开花间隔天数(ASI)、结穗率和籽粒产量进行了数量性状位点(QTL)定位及基因效应分析.结果表明,在两种水分处理下,ASI、结穗率与籽粒产量的相关性均达到显著水平(P＜0.05).在灌溉和干旱胁迫下,分别检测到3个和2个控制ASI的QTL,位于第1、2、3和第2、5染色体上.在灌溉条件下,在第3和第6染色体上各检测到1个控制结穗率的QTL,基因作用方式呈加性或部分显性,可解释19.9%的表型变异;在干旱条件下,在第3、 7、10染色体上共检测到4个控制结穗率的QTL,基因作用方式为显性或部分显性,可解释60.4%的表型变异.在灌溉和干旱胁迫下,控制产量的QTL分别定位在第3、6、7和第1、2、4、8染色体上,基因作用方式均以加性或部分显性为主,可解释的表型变异为7.3%～22.0%.在干旱条件下,借助连锁分子标记和基因效应分析,可构建包含ASI、结穗率和产量QTL的选择指数,用于分子标记辅助育种.