Red:far-red light conditions affect the emission of volatile organic compounds from barley (Hordeum vulgare), leading to altered biomass allocation in neighbouring plants

Background and Aims Volatile organic compounds (VOCs) play various roles in plant–plant interactions, and constitutively produced VOCs might act as a cue to sense neighbouring plants. Previous studies have shown that VOCs emitted from the barley (Hordeum vulgare) cultivar ‘Alva’ cause changes in biomass allocation in plants of the cultivar ‘Kara’. Other studies have shown that shading and the low red:far-red (R:FR) conditions that prevail at high plant densities can reduce the quantity and alter the composition of the VOCs emitted by Arabidopsis thaliana, but whether this affects plant–plant signalling remains unknown. This study therefore examines the effects of far-red light enrichment on VOC emissions and plant–plant signalling between ‘Alva’ and ‘Kara’.Methods The proximity of neighbouring plants was mimicked by supplemental far-red light treatment of VOC emitter plants of barley grown in growth chambers. Volatiles emitted by ‘Alva’ under control and far-red light-enriched conditions were analysed using gas chromatography–mass spectrometry (GC-MS). ‘Kara’ plants were exposed to the VOC blend emitted by the ‘Alva’ plants that were subjected to either of the light treatments. Dry matter partitioning, leaf area, stem and total root length were determined for ‘Kara’ plants exposed to ‘Alva’ VOCs, and also for ‘Alva’ plants exposed to either control or far-red-enriched light treatments.Key Results Total VOC emissions by ‘Alva’ were reduced under low R:FR conditions compared with control light conditions, although individual volatile compounds were found to be either suppressed, induced or not affected by R:FR. The altered composition of the VOC blend emitted by ‘Alva’ plants exposed to low R:FR was found to affect carbon allocation in receiver plants of ‘Kara’.Conclusions The results indicate that changes in R:FR light conditions influence the emissions of VOCs in barley, and that these altered emissions affect VOC-mediated plant–plant interactions.     

城市植物源挥发性有机化合物排放特征及其大气环境效应研究进展

在外界环境的刺激下,植物会通过释放挥发性有机化合物来维护自身生长。城市是人类活动的主要集聚地,剧烈的人为干扰导致城市环境特征呈现出复杂的变化趋势,从而使城市植物排放挥发性有机化合物的过程与自然界出现较大差异。城市中的植物源挥发性有机化合物(Biogenic Volatile Organic Compounds, BVOCs)会直接与城市中的氧化物质接触,生成二次污染物,并在高温、强光照的条件下发生光化学反应,严重破坏城市大气环境,危害居民健康。总结了城市BVOCs的常见类型、作用机制及现有研究方法,分析了不同时间、空间和人类活动背景下的城市BVOCs排放特征,并进一步梳理了当前研究的不足,提出未来重点研究方向,旨在为大气环境治理、环境空间规划、居民健康保障等方面的城市管理工作提供指导。     

QTL analysis of resistance to the rice blast pathogen in barley (Hordeum vulgare)

Barley is compatible with the rice blast pathogen (Pyricularia oryzae Cav.). Fiftyfour barley cultivars of diverse geographic origin and pedigree were inoculated with three isolates of the rice blast pathogen. All barley genotypes showed blast disease symptoms when inoculated at the seedling stage with each of the three isolates. However, one genotype showed quantitative resistance to all three isolates and three genotypes showed quantitative resistance to one or two of the isolates. By inoculating a set of doubled-haploid lines derived from the cross ’Harrington’ (susceptible) and ’TR306’ (resistant) with isolate Ken 54–20, we mapped quantitative trait loci (QTLs) determining seedling stage blast resistance. At all QTLs, TR306 contributed the resistance alleles. The four QTLs, when considered jointly, explained 43.6% of the phenotypic variation in blast symptom expression. A comparison of the blast resistance QTLs with other disease resistance QTLs reported in this population revealed a region on chromosome 4 (4H) with multiple disease resistance loci. It will be useful to capitalize on the syntenic relationship of rice and barley and to integrate information on species-specific resistance genes with information on the reaction of the two species to the same pathogen. Received: 7 January 2000 / Accepted: 22 September 2000     

Effect of pre-sowing exposure of seeds to gamma-radiation on the drought resistance behaviour of barley plants (Hordeum vulgare L.)

Summary With a view to examine the effect of pre-sowing exposure of seeds to gamma radiation (3000 r) on the drought resistance behaviour of barley plants (Hordeum vulgare L., Var. K₁₂), a pot-culture experiment was conducted at a glasshouse attached to the Department of Plant Physiology. The plants were subjected to wilting treatments at tillering stage and were maintained so for ten days. Subsequently, observations on survival capacity, growth behaviour and physiological changes were made during the wilting period. The data obtained were subjected to statistical analysis. Reduction in soil moisture causes a set-back in the physiological status of barley plants and thereby inhibits the crop growth. Presowing exposure of seeds to gamma-radiation induced drought tolerance in barley plants. It not only improved the growth behaviour but also maintained an active metabolism in plants even under wilting condition. Although the investigation is of preliminary nature, but it certainly offers newer scope of research towards useful utilization of gamma radiation in relation to drought tolerance in crops. Reader in Plant Physiology.     

Uzu mutation in barley (Hordeum vulgare L.) reduces the leaf unrolling response to brassinolide

A sensitive method to examine the brassinolide (BL) response of barley (Hordeum vulgare L.) using dark-grown leaf segments was established based on the known method for wheat. BL responses of 53 dwarf isogenic lines of barley were examined, and two lines were found having a uzu gene that doesn't respond significantly. These results indicate that uzu dwarfism may be caused by the non-responding character to BL.     

The nucleotide sequences of chloroplast 4.5 S rRNAs from four species of plants,celery (Apium graveoleus), barley (Hordeum vulgare), Chinese chive (Allium tuberosum) and dayflower (Commelina communis)

Four chloroplast 4.5 S rRNAs were isolated from the respective plant leaves by a simple method. The complete nucleotide sequences were determined using rapid gel sequencing techniques. The sequences are highly conserved among chloroplast 4.5 S rRNAs. The 4.5 S rRNAs of celery, Chinese chive and dayflower are 103 nucleotides long and that of barley 95 nucleotides long. The 7-nucleotide sequence from position 28–34 is absent in monocotyledon barley 4.5 S rRNA but is present in monocotyledon Chinese chive and day-flower.     

Endosperm-specific expression of green fluorescent protein driven by the hordein promoter is stably inherited in transgenic barley (Hordeum vulgare) plants

The expression of green fluorescent protein (GFP) and its inheritance were studied in transgenic barley (Hordeum vulgare L.) plants transformed with a synthetic green fluorescent protein gene [sgfp(S65T)] driven by either a rice actin promoter or a barley endosperm-specific d-hordein promoter. The gene encoding phosphinothricin acetyltransferase (bar), driven by the maize ubiquitin promoter and intron, was used as a selectable marker to identify transgenic tissues. Strong GFP expression driven by the rice actin promoter was observed in callus cells and in a variety of tissues of T0 plants transformed with the sgfp(S65T)-containing construct. GFP expression, driven by the rice actin promoter, was observed in 14 out of 17 independent regenerable transgenic callus lines; however, expression was gradually lost in T0 and later generation progeny of diploid lines. Stable GFP expression was observed in T2 progeny from only 6 out of the 14 (43%) independent GFP-expressing callus lines. Four of the 8 lines not expressing GFP in T2 progeny, lost GFP expression during T0 plant regeneration from calli; one lost GFP expression in the transition from the T0 to T1 generations and three lines were sterile. Similarly, expression of bar driven by the maize ubiquitin promoter was lost in T1 progeny; only 21 out of 26 (81%) independent lines were Basta-resistant. In contrast to actin-driven expression, GFP expression driven by the d-hordein promoter exhibited endosperm-specificity. All seven lines transformed with d-hordein-driven GFP (100%) expressed GFP in the T1 and T2 generations, regardless of ploidy levels, and expression segregated in a Mendelian fashion. We conclude that the sgfp(S65T) gene was successfully transformed into barley and that GFP expression driven by the d-hordein promoter was more stable in its inheritance pattern in T1 and T2 progeny than that driven by the rice actin promoter or the bar gene driven by the maize ubiquitin promoter.     

The development of antenna complexes of barley (Hordeum vulgare cv. Akcent) under different light conditions as judged from the analysis of 77 K chlorophyll a fluorescence spectra

Using 77 K chlorophyll a (Chl a) fluorescence spectra in vivo, the development was studied of Photosystems II (PS II) and I (PS I) during greening of barley under intermittent light followed by continuous light at low (LI, 50 μmol m⁻² s⁻¹) and high (HI, 1000 μmol m⁻² s⁻¹) irradiances. The greening at HI intermittent light was accompanied with significantly reduced fluorescence intensity from Chl b excitation for both PS II (F685) and PS I (F743), in comparison with LI plants, indicating that assembly of light-harvesting complexes (LHC) of both photosystems was affected to a similar degree. During greening at continuous HI, a slower increase of emission from Chl b excitation in PS II as compared with PS I was observed, indicating a preferred reduction in the accumulation of LHC II. The following characteristics of 77 K Chl a fluorescence spectra documented the photoprotective function of an elevated content of carotenoids in HI leaves: (1) a pronounced suppression of Soret region of excitation spectra (410–450 nm) in comparison with the red region (670–690 nm) during the early stage of greening indicated a strongly reduced excitation energy transfer from carotenoids to the Chl a fluorescing forms within PS I and PS II; (2) changes in the shape of the excitation band of Chl b and carotenoids (460–490 nm) during greening under continuous light confirmed that the energy transfer from carotenoids to Chl a within PS II remained lower as compared with the LI plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

AB-QTL analysis reveals new alleles associated to proline accumulation and leaf wilting under drought stress conditions in barley (Hordeum vulgare L.)

ABSTRACT: BACKGROUND: Land plants have evolved several measures to maintain their life against abiotic stresses. The accumulation of proline is the most generalized response of plants under drought, heat or salt stress conditions. It is known as an osmoprotectant which also acts as an instant source of energy during drought recovery process. But, both its role and genetic inheritance are poorly understood in agriculture crops. In the present work, advanced backcross quantitative trait locus (AB-QTL) analysis was performed to elucidate genetic mechanisms controlling proline accumulation and leaf wilting in barley under drought stress conditions. RESULTS: The analysis revealed eight QTL associated to proline content (PC) and leaf wilting (WS). QTL for PC were localized on chromosome 3 H, 4 H, 5 H and 6 H. The strongest QTL effect QPC.S42.5 H was detected on chromosome 5 H where drought inducible exotic allele was associated to increase PC by 54%. QTL effects QPC.S42.3 H, QPC.S42.4 H and QPC.S42.6 H were responsible to heighten PC due to the preeminence of elite alleles over the exotic alleles which ranged from 26% to 43%. For WS, QTL have been localized on chromosome 1 H, 2 H, 3 H and 4 H. Among these, QWS.S42.1 H and QWS.S42.4 H were associated to decrease in WS due to the introgression of exotic alleles. In addition, two digenic epistatic interaction effects were detected for WS where the additive effect of exotic alleles imparted a favorable increase in the trait value. CONCLUSIONS: The present data represents a first report on whole-genome mapping of proline accumulation and leaf wilting in barley. The detected QTL are linked to new alleles from both cultivated and wild accessions which bring out an initial insight on the genetic inheritance of PC and WS. These QTL alleles are fixed in the isogenic background of Scarlett, which will allow for positional cloning of underlying genes and to develop drought resilient barley cultivars.     

Changes in organic compounds secreted by roots in two Poaceae species (Hordeum vulgare and Polypogon monspenliensis) subjected to iron deficiency

Journal of Plant Research - Despite their economic and ecological interests, Poaceae are affected by the low availability of iron in calcareous soils. Several studies focused on the capacity of...     

The function of proteases during the light-dependent transformation of etioplasts to chloroplasts in barley (Hordeum vulgare L.)

The role of proteolysis during the light-induced rapid decrease of the NADPH: protochlorophyllide oxidoreductase in barley was studied. A proteolytic activity with a pH optimum of 4.5 was present in a plastid preparation of etiolated barley seedlings. No other proteolytic activity could be detected. The temperature optimum for the proteolysis was 50°C, and the highest specific activity was measured with hemoglobin as the substrate. In contrast to previous proposals, no evidence for the specific involvement of this protease was found during the light-induced transformation of etioplasts to chloroplasts.     

Control by phytochrome of the synthesis of protein related to senescence in chloroplasts of barley (Hordeum vulgare)

Protein synthesis has been measured in chloroplast isolated from detached leaves of barley ( Hordeum vulgare L. cv. Hassan). The effects of hormone and light treatments of the leaves on chloroplast protein synthesis have been compared with effects on other senescence symptoms. Interruption of the dark with red light retards senescence and increases chloroplast protein synthesis. The effect of red light was reversed by far-red light. Red light did not act additively with kinetin, and it competed with ethylene and abscisic acid, accelerators of senescence, which decreased protein synthesis. In contrast to the interruption of the dark with red light, continuous light decreased chloroplast protein synthesis. It may be concluded effects on chloroplast protein synthesis. The retardation of senescence by continuous light is not necessarily related to P_u Instead, energy provided by photosynthesis may be an important factor.     

Analysis of the genome of plants. II. Characterization of repetitive DNA in barley (Hordeum vulgare) and wheat (Triticum aestivum).

Barley and wheat DNAs have been characterized by studying their kinetics of reassociation, melting properties and sedimentation behaviour in neutral CsCl gradients as well as in Cs2SO4 gradients containing Ag+ or Hg2+. In both species, reassociation kinetics have revealed the presence of approx. 76% redundant nucleotide sequences which have been grouped into very rapidly reassociating (Cot 0-0.01), rapidly reassociating (Cot 0.01-1.0) and slowly reassociating (Cot 1-100) fractions. The barley Cot 0-0.01 and Cot 0.01-1.0 fractions as well as the wheat Cot 0.01-1.0 fraction form narrow bands upon centrifugation in CsCl gradients. Under similar experimental conditions both Cot 0.01 and Cot 1.0-100 wheat fractions and the barley Cot 1.0-100 fraction form broad bands each having several shoulders. Thermal denaturation studies of most of the above reassociated fractions have shown a considerable degree of order in their duplexes with an average hyperchromicity of 21.5%. When native, high molecular weight barley DNA is centrifuged in Ag+/CS2SO4 density gradients (RF = 0.2), two satellites appear on the heavier side of the main band, as against one in the case of wheat. The two minor peaks, designated as satellites I and II, have buoyant densities of 1.702 and 1.698 g/cm3, respectively, in neutral CsCl gradients and together represent about 8-9% of total barley DNA. Upon centrifugation in Hg2+/CS2SO4 density gradients, one satellite is observed in both barley and wheat and it accounts for 1-2% of their genomes.     

迷迭香对干旱胁迫的生理响应及其诱导挥发性有机化合物的释放

为探讨干旱胁迫对迷迭香(Rosmarinus officinalis)生理生化特性及挥发性有机化合物(VOC)释放规律的影响, 该文采用盆栽称重控水法研究了轻度(LD)、中度(MD)和重度(SD)干旱胁迫对迷迭香二年生实生苗叶片细胞膜透性、可溶性糖、可溶性蛋白质和丙二醛(MDA)含量以及脂氧合酶和抗氧化保护酶活性的影响, 并采用热脱附/气相色谱/质谱联用技术对不同干旱胁迫下迷迭香释放的挥发性有机化合物成分进行了分析。结果表明: 干旱胁迫对迷迭香叶片可溶性糖和可溶性蛋白质含量有明显的影响, MD和SD处理12天时其含量极显著地增加(p < 0.01), 与对照相比可溶性糖分别增加了51.5%和87.4%, 可溶性蛋白质含量分别增加了0.82和1.40倍。在MD和SD胁迫下, 超氧化物歧化酶、过氧化物酶和过氧化氢酶对干旱胁迫的响应存在一定差异, 表现为相互协调的作用。随着干旱胁迫时间的延长, 迷迭香体内MDA含量极显著地增加(p < 0.01), 细胞膜损伤率显著增加。分析显示, 迷迭香释放的VOC主要是萜烯类化合物, 占总量的46.0%以上; 随着干旱胁迫增强, 迷迭香释放的VOCs总量减少, 种类增多; LD、MD和SD胁迫处理萜烯类化合物相对含量与对照相比分别增加了14.4%、17.0%和23.7%; 干旱胁迫还明显诱导绿叶挥发物(green leaf volatiles)和醛类化合物的释放, 诱导产生了2-己烯醛、叶醇、山梨醛和癸醛4种新组分。研究表明: 干旱胁迫条件下, 迷迭香能够通过调节保护酶活性、渗透调节物质含量和释放VOCs来提高抗旱性。     

Influence of barley straw (Hordeum vulgare L.) extract on phytoplankton dominated by Scenedesmus species in laboratory conditions: the importance of the extraction duration

The response of a natural phytoplankton assemblage dominated by algae of the genus Scenedesmus to the addition of barley straw extract was studied in a laboratory experiment. The aim of the study was to compare the inhibiting effect of water extracts obtained by soaking the straw for 1, 2 and 3 months. We analysed the response of four species, Scenedesmus subspicatus, Scenedesmus ecornis, Scenedesmus quadricauda and Scenedesmus acuminatus, during 14 days of their exposure to different types of barley straw extract. S. subspicatus and S. ecornis responded with decreasing numbers only to the addition of the 3-month solution (ANOVA; F?=?290.1, p <0.001; and F?=?11.8, p <0.01, respectively); the two other species were inhibited by all types of extracts. The results indicate the need for more research on the importance of extraction duration to the inhibitory abilities of barley straw which can be applied in the management of water quality in water bodies.     

Isolation and identification of proteins from the peptide-transport carrier in the scutellum of germinating barley (Hordeum vulgare L.) embryos

Peptide-transport proteins, intrinsic to the epithelial plasmalemmae of the scutella of germinating barley (Hordeum vulgare L.) embryos, have been selectively labelled with p-chloro-[²⁰³Hg]mercuribenzenesulphonate using both a substrate-screening technique and a procedure developed to label exclusively vicinal dithiol groups, which were shown previously (Walker-Smith and Payne, 1983, FEBS Lett. 160, 25–30) to be essential components of the peptide-transport system. After radioactive labelling, proteins from the scutellar membranes have been solubilised with lithium diiodosalicylate plus sodium dodecyl sulphate and separated by using polyacrylamide gel electrophoresis. Fluorography and silver staining of these gels has for the first time allowed identification of two presumptive components of the peptide-transport system. These components only become detectable in an extract of the scutellar epithelia after 15 h imbibition, concomitant with a dramatic increase in peptide-transport activity, and they remain present at least 3 d after the onset of germination. [³⁵] Methionine was shown to be incorporated into these proteins between 15–20 h after imbibition, but its incorporation during a similar 5 h period into scutella isolated after 3 d was undetectable, implying a slow turnover of these proteins during the later stages of germination.Abbreviations Ala₂, Ala₃ dialanine, trialanine - CHAPS 3-((3-cholamidopropyl) dimethylammonio)-1-propanesulphonate - p-CMBS p-chloromercuribenzenesulphonic acid - NEM N-ethylmaleimide - SDS-PAGE sodium dodecyl sulphate-polyacrylamide gel electrophoresis - Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol     

Rph22: mapping of a novel leaf rust resistance gene introgressed from the non-host Hordeum bulbosum L. into cultivated barley (Hordeum vulgare L.)

A resistance gene (Rph22) to barley leaf rust caused by Puccinia hordei was introgressed from the non-host species Hordeum bulbosum into cultivated barley. The H. bulbosum introgression in line ‘182Q20’ was located to chromosome 2HL using genomic in situ hybridisation (GISH). Using molecular markers it was shown to cover approximately 20 % of the genetic length of the chromosome. The introgression confers a very high level of resistance to P. hordei at the seedling stage that is not based on a hypersensitive reaction. The presence of the resistance gene increased the latency period of the leaf rust fungus and strongly reduced the infection frequency relative to the genetic background cultivar ‘Golden Promise’. An F₂ population of 550 individuals was developed and used to create a genetic map of the introgressed region and to determine the map position of the underlying resistance gene(s). The resistance locus, designated Rph22, was located to the distal portion of the introgression, co-segregating with markers H35_26334 and H35_45139. Flanking markers will be used to reduce the linkage drag, including gene(s) responsible for a yield penalty, around the resistance locus and to transfer the gene into elite barley germplasm. This genetic location is also known to harbour a QTL (Rphq2) for non-hypersensitive leaf rust resistance in the barley cultivar ‘Vada’. Comparison of the ‘Vada’ and H. bulbosum resistances at this locus may lead to a better understanding of the possible association between host and non-host resistance mechanisms.     

A flavonoid mutant of barley (Hordeum vulgare L.) exhibits increased sensitivity to UV-B radiation in the primary leaf

The aim of the present investigation was to define the role of soluble flavonoids as UV-B protectants in the primary leaf of barley (Hordeum vulgare L.). For this purpose we used a mutant line (Ant 287) from the Carlsberg collection of proanthocyanidin-free barley containing only 7% of total extractable flavonoids in the primary leaf as compared to the mother variety (Hiege 550/75). Seven-day-old leaves from plants grown under high visible light with or without supplementary UV-B radiation were used for the determination of UV-B sensitivity. UV-B-induced changes were assessed from parameters of chlorophyll fluorescence of photosystem II, including initial and maximum fluorescence, apparent quantum yield, and photochemical and non-photochemical quenching. A quartz fibre-optic microprobe was used to evaluate the amount of potentially harmful UV-B (310 nm radiation) penetrating into the leaf as a direct consequence of flavonoid deficiency. Our data indicate an essential role of flavonoids in UV-B protection of barley primary leaves. In leaves of the mutant line grown under supplementary UV-B, an increase in 310nm radiation in the mesophyll and a strong decrease in the quantum yield of photosynthesis were observed as compared to the corresponding mother variety. Primary leaves of liege responded to supplementary UV-B radiation with a 30% increase in the major flavonoid saponarin and a 500% increase in the minor compound lutonarin. This is assumed to be an efficient protective response since no changes in variable chlorophyll fluorescence were apparent. In addition, a further reduction in UV-B penetration into the mesophyll was recorded in these leaves.