Dactylis glomerata

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Florence Volaire - One of the best experts on this subject based on the ideXlab platform.

  • coping with drought root trait variability within the perennial grass Dactylis glomerata captures a trade off between dehydration avoidance and dehydration tolerance
    Plant and Soil, 2019
    Co-Authors: Pauline Bristiel, Catherine Roumet, Cyrille Violle, Florence Volaire
    Abstract:

    Understanding plant adaptation to drought is a crucial challenge under climate change. This study aimed to investigate root traits and water use of grass populations exhibiting a range of dehydration avoidance and tolerance strategies to cope with drought. Sixteen populations of the perennial grass Dactylis glomerata originating from three biogeographical origins (Northern, Temperate and Mediterranean) were grown in long tubes. Plant biomass, rooting depth and morphological traits of deep roots were measured both under full irrigation and under severe drought. Water uptake under drought was used as a proxy for dehydration avoidance. Plant survival after severe drought was used as a measure of dehydration tolerance. All populations had similar maximum rooting depth and specific root length. Compared to Northern and Temperate populations, Mediterranean populations had half the total and deep root biomass, but thinner and denser deep roots. They were less affected by drought. These traits were associated with less water uptake (lower dehydration avoidance) but greater survival to severe drought (enhanced dehydration tolerance). The intraspecific variability in root traits revealed a trade-off between dehydration avoidance and dehydration tolerance which illustrates contrasting adaptive plant and root strategies associated with the biogeographical origins of populations.

  • Embolism and mechanical resistances play a key-role in dehydration tolerance of a perennial grass Dactylis glomerata L
    Annals of Botany, 2018
    Co-Authors: Florence Volaire, Pauline Bristiel, Cyrille Violle, Frederic Lens, Hervé Cochard, Hueng Xu, Larissa Chacon Doria, Jennifer A. Balachowski, Nick Rowe, Catherine Picon-cochard
    Abstract:

    Background and Aims : More intense droughts under climate change threaten species resilience. Hydraulic strategies determine drought survival in woody plants but have been hardly studied in herbaceous species. We explored the intraspecific variability of hydraulic and morphological traits as indicators of dehydration tolerance in a perennial grass, cocksfoot (Dactylis glomerata), which has a large biogeographical distribution in Europe. Methods : Twelve populations of cocksfoot originating from Mediterranean, Temperate and Northern European areas were grown in a controlled environment in pots. Dehydration tolerance, leaf and stem anatomical traits and xylem pressure associated with 88 or 50 % loss of xylem conductance (P88, P50) were measured. Key Results : Across the 12 populations of cocksfoot, P50 ranged from –3.06 to – 6.36 MPa, while P88 ranged from –5.06 to –11.6 MPa. This large intraspecific variability of embolism thresholds corresponded with the biogeographical distribution and some key traits of the populations. In particular, P88 was correlated with dehydration tolerance (r = –0.79). The dehydration-sensitive Temperate populations exhibited the highest P88 (–6.1 MPa). The most dehydration-tolerant Mediterranean populations had the greatest leaf dry matter content and leaf fracture toughness, and the lowest P88 (–10.4 MPa). The Northern populations displayed intermediate trait values, potentially attributable to frost resistance. The thickness of metaxylem vessel walls in stems was highly correlated with P50 (r = –0.92), but no trade-off with stem lignification was observed. The relevance of the linkage between hydraulic and stomatal traits is discussed for drought survival in perennial grasses. Conclusions : Compared with woody species, the large intraspecific variability in dehydration tolerance and embolism resistance within cocksfoot has consequences for its sensitivity to climate change. To better understand adaptive strategies of herbaceous species to increasing drought and frost requires further exploration of the role of hydraulic and mechanical traits using a larger inter- and intraspecific range of species.

  • seasonal patterns of growth dehydrins and water soluble carbohydrates in genotypes of Dactylis glomerata varying in summer dormancy
    Annals of Botany, 2005
    Co-Authors: Florence Volaire, Mark Norton, G M Norton, F Lelievre
    Abstract:

    • Background and Aims Summer dormancy in perennial grasses has been studied inadequately, despite its potential to enhance plant survival and persistence in Mediterranean areas. The aim of the present work was to characterize summer dormancy and dehydration tolerance in two cultivars of Dactylis glomerata (dormant ‘Kasbah’, non-dormant ‘Oasis’) and their hybrid using physiological indicators associated with these traits. • Methods Dehydration tolerance was assessed in a glasshouse experiment, while seasonal metabolic changes which produce putative protectants for drought, such as carbohydrates and dehydrins that might be associated with summer dormancy, were analysed in the field. • Key Results The genotypes differed in their ability to survive increasing soil water deficit: lethal soil water potential (Ψs) was −3·4 MPa for ‘Kasbah’ (although non-dormant), −1·3 MPa for ‘Oasis’, and −1·6 MPa for their hybrid. In contrast, lethal water content of apices was similar for all genotypes (approx. 0·45 g H2O g d. wt−1), and hence the greater survival of ‘Kasbah’ can be ascribed to better drought avoidance rather than dehydration tolerance. In autumn-sown plants, ‘Kasbah’ had greatest dormancy, the hybrid was intermediate and ‘Oasis’ had none. The more dormant the genotype, the lower the metabolic activity during summer, and the earlier the activity declined in spring. Decreased monosaccharide content was an early indicator of dormancy induction. Accumulation of dehydrins did not correlate with stress tolerance, but dehydrin content was a function of the water status of the tissues, irrespective of the soil moisture. A protein of approx. 55 kDa occurred in leaf bases of the most dormant cultivar even in winter. • Conclusions Drought avoidance and summer dormancy are correlated but can be independently expressed. These traits are heritable, allowing selection in breeding programmes.

  • Drought survival, summer dormancy and dehydrin accumulation in contrasting cultivars of Dactylis glomerata
    Physiologia Plantarum, 2002
    Co-Authors: Florence Volaire
    Abstract:

    To study survival under prolonged and severe drought in the perennial grass Dactylis glomerata we compared dormant, resistant and sensitive cultivars (cvs.) in both field and glasshouse experiments. Water status, membrane stability and expression of dehydrins were assessed in the immature leaf bases, which are the last surviving organs. Analysis of leaf elongation and senescence of aerial tissues showed that dormancy was exhibited by the potentially dormant cultivar (cv.) only in the field. This cultivar exhibited a high survival rate, similar levels of dehydration and expression of a low‐molecular weight (22–24 kDa) dehydrin in both drought and irrigated plants, whether fully dormant or not. At the same level of soil water deficit, there were no differences between the non‐dormant drought resistant and drought sensitive cultivars in plant water status and membrane stability. However, the accumulation of dehydrins as drought progressed was markedly different between these cultivars and was associated with their contrasting survival. The possible role of the major low‐molecular dehydrins in maintenance of cell integrity under dehydration is discussed with reference to both summer dormancy and survival under severe drought.

  • Drought survival and dehydration tolerance in Dactylis glomerata and Poa bulbosa
    Australian Journal of Plant Physiology, 2001
    Co-Authors: Florence Volaire, Geneviève Conéjèro, François Lelièvre
    Abstract:

    To analyse the contribution of dormancy and dehydration tolerance to drought survival of perennial grasses, we compared Poa bulbosa L., which is classified as a resurrection plant, with one of the most drought resistant cultivars of Mediterranean Dactylis glomerata L. Comparing periods when dormancy was induced in Poa (summer) and not induced (winter), we aimed to ascertain the presence of differential plant responses between dormancy and dehydration tolerance and to characterise water status, sugar and dehydrin accumulation in surviving organs of Poa and Dactylis, in relation to their ability to survive intense drought. Irrespective of the dormancy status of Poa, the bulbs of this species had a final water content lower than 10% and survived an extreme drought. This could be associated with the accumulation of sucrose and the expression of a high number (>10) of dehydrins that peaked when the water content of the bulbs fell below 50%, whether this dehydration was due to dormancy induction or increasing soil water deficit. The independence of dormancy to dehydration tolerance was reinforced by the expression of a specific dehydrin (approx. 28 kDa) found only in irrigated, but dormant, tissues of Poa. The Dactylis exhibited contrasting survival between experiments (46 and 0% after a summer and winter drought, respectively). The mortality was associated with a significantly higher rate of decrease of the membrane stability of leaf bases of Dactylis in winter and with barely detectable amounts of sucrose contents in droughted roots. However, neither the water-soluble carbohydrate concentration in leaf bases nor the overall accumulation of dehydrins could be related to the contrasting survival of this Dactylis between the two seasons. Since in seeds of Poa and Dactylis, the accumulation of dehydrins was comparable with that found in droughted aerial tissues of the same species, the expression of these proteins must interact with other mechanisms to confer dehydration tolerance.

Roland Kolliker - One of the best experts on this subject based on the ideXlab platform.

  • indicators for genetic and phenotypic diversity of Dactylis glomerata in swiss permanent grassland
    Ecological Indicators, 2014
    Co-Authors: Gisela Luscher, Franco Widmer, Beat Boller, Roland Kolliker
    Abstract:

    Abstract Genetic diversity is the fundamental level of biological diversity. In the discussion of biological diversity in agricultural ecosystems, this level is of major importance, but often neglected. Tools for the direct measurement of genetic diversity, especially in highly diverse systems such as permanent grassland, are demanding and the relationship between genetic diversity and management practices or environmental factors is poorly understood. Genetic diversity of the common grassland species Dactylis glomerata was assessed using genetic diversity indices based on 29 SSR markers. Phenotypic diversity within and among selected populations was evaluated in a replicated field experiment based on ten phenotypic plant characters of agronomic relevance. Twenty populations of D. glomerata from permanent grassland from the Swiss Alps were included in the analysis. We investigated correlations between genetic diversity (genotypic/phenotypic) and farming system (conventional/organic), management intensity (intensive/extensive), three plant species diversity indices, five ecological and five habitat parameters at collection sites. Genetic and phenotypic variability within and among populations of D. glomerata was large. The intensive management of permanent grassland reduced genotype diversity and genetic variation of the plant character ‘flowering time’, while conventional farming systems increased the average expected heterozygosity within populations of D. glomerata. Populations from extensively managed sampling sites accommodated significantly smaller D. glomerata individuals. SSR markers and phenotypic characters proved to be valuable tools for the assessment of genetic and phenotypic diversity considering different perspectives. Management parameters were the main factors influencing genotypic diversity and phenotypic characteristics in natural populations of D. glomerata in permanent grassland.

  • genetic diversity of natural orchardgrass Dactylis glomerata l populations in three regions in europe
    BMC Genetics, 2013
    Co-Authors: Franco Widmer, Wendy Fjellstad, Siyka Stoyanova, Roland Kolliker
    Abstract:

    Dactylis glomerata (orchardgrass or cocksfoot) is a forage crop of agronomic importance comprising high phenotypic plasticity and variability. Although the genus Dactylis has been studied quite well within the past century, little is known about the genetic diversity and population patterns of natural populations from geographically distinct grassland regions in Europe. The objectives of this study were to test the ploidy level of 59 natural and semi-natural populations of D. glomerata, to investigate genetic diversity, differentiation patterns within and among the three geographic regions, and to evaluate selected populations for their value as genetic resources. Among 1861 plants from 20 Swiss, 20 Bulgarian and 19 Norwegian populations of D. glomerata, exclusively tetraploid individuals were identified based on 29 SSR markers. The average expected heterozygosity (HE,C) ranged from 0.44 to 0.59 and was highest in the Norwegian region. The total number of rare alleles was high, accounting for 59.9% of the amplified alleles. 80.82% of the investigated individuals could be assigned to their respective geographic region based on allele frequencies. Average genetic distances were low despite large geographic distances and ranged from D = 0.09 to 0.29 among populations. All three case study regions revealed high genetic variability of tetraploid D. glomerata within selected populations and numerous rare and localized alleles which were geographically unique. The large, permanent grassland patches in Bulgaria provided a high genetic diversity, while fragmented, semi-natural grassland in the Norwegian region provided a high amount of rare, localized alleles, which have to be considered in conservation and breeding strategies. Therefore, the selected grassland populations investigated conserve a large pool of genetic resources and provide valuable sources for forage crop breeding programs.

  • effect of season and cutting frequency on root and shoot competition between festuca pratensis and Dactylis glomerata
    Grass and Forage Science, 2002
    Co-Authors: C Carlen, Roland Kolliker, Beat Reidy, A Luscher, Josef Nösberger
    Abstract:

    Plant competition strongly affects the species composition of managed grassland. To identify relevant processes, Festuca pratensis (Huds.) and Dactylis glomerata (L.) were grown as monocultures or mixtures in boxes placed in the field for two seasons and subjected to two cutting frequencies. Root and shoot competition effects were separated using soil and aerial partitions. Shoot competition was analysed by measuring the vertical distribution of the leaf area and root competition by analysing the absorption of tracers. Values of relative yield indicated that the two grasses fully competed for the same limiting resources under the experimental conditions. The competitive ability of F. pratensis was lower during both years relative to D. glomerata. This was mainly related to its consistently lower shoot competitive ability, which was associated with less leaf area in the upper layers of the canopy and shorter leaves. Root competitive ability of F. pratensis changed with season. It was similar to that of D. glomerata during spring and autumn, but less during summer. The lower root competitive ability in summer might be due to the lower root activity of F. pratensis, measured as rubidium (Rb) and strontium (Sr) absorption in July, 0·1 and 0·2 m below the ground. Cutting frequency did not greatly influence the relative importance of root and shoot competition during the first growing season. However, under infrequent defoliation, the competitive ability of F. pratensis decreased markedly in full competition during the second growing season. These results suggest that distinct differences in the canopy structure and root activity of different plant species can affect the relative importance of root and shoot competition during the season.

  • genetic variability of forage grass cultivars a comparison of festuca pratensis huds lolium perenne l and Dactylis glomerata l
    Euphytica, 1999
    Co-Authors: Roland Kolliker, Beat Reidy, F J Stadelmann, Josef Nösberger
    Abstract:

    Three widely used cultivars of each of the species Festuca pratensis Huds., Lolium perenne L., and Dactylis glomerata L. were investigated by means of randomly amplified polymorphic DNA (RAPD) markers and vegetative growth traits in order to investigate genetic variability within each cultivar and to compare the level of diversity among cultivars and species. RAPD markers allowed a clear separation of the three species. Genetic variability based on RAPD markers was considerably lower for F. pratensis cultivars than for L. perenne and D. glomerata cultivars which showed similar levels of variability. The proportion of variability due to variation within cultivars, determined by an analysis of molecular variance, was lower in F. pratensis (64.6%) than in L. perenne (82.4%) and D. glomerata (85.1%). A comparison of F. pratensis and L. perenne, based on vegetative growth traits, confirmed the differences in genetic variability within cultivars. F. pratensis showed lower coefficients of genetic variation for eight of ten traits when compared to L. perenne. This study demonstrates considerable differences in genetic variability which may have consequences for the adaptability and persistency of individual cultivars.

D Francis - One of the best experts on this subject based on the ideXlab platform.

  • genome size is negatively correlated with altitude in natural populations of Dactylis glomerata
    Annals of Botany, 1998
    Co-Authors: D Francis, Gail Reeves, Stuart M Davies, Hilary J Rogers, Trevor R Hodkinson
    Abstract:

    Previously, we found a significant negative correlation between DNA C-value and altitude among eight natural populations of Dactylis glomerata L. (Creber et al., New Phytologist 128: 555-561, 1994). We have examined the extent to which similar negative relationships exist in other altitudinal transects, one in southern France and the other in Italy. Using Feulgen microdensitometry, C-values were negatively correlated with altitude both for the French and Italian populations. A combined plot of DNA C-values against altitude for all of the transects (representing C-values for 17 natural populations), exhibited a highly significant negative relationship; there was a 13-fold variation in DNA C-value from the largest genome-lowest altitude to the smallest genome-highest altitude natural population. Such a consistent marked altitudinal dine suggests strong nucleotypic selection acting upon these populations with increasing altitude. Preliminary examination of amplified fragment length polymorphisms between populations selected from the upper and lower limits of the French and Italian transects has shown that these populations are genetically distinct. The extent to which this genetic separation is related to altitude or genome size, or both, is discussed. © 1998 Annals of Botany Company

  • elevated co2 stimulates cells to divide in grass meristems a differential effect in two natural populations of Dactylis glomerata
    Plant Cell and Environment, 1997
    Co-Authors: E A Kinsman, M S Davies, D Francis, C Lewis, J E Young, B Vilhar, Helen J Ougham
    Abstract:

    In this study, we tested the hypothesis that elevated [CO 2 ] shortens the cell cycle in meristems of Dactylis glomerata, more in a Portuguese population (38°53'N) than in a Swedish population (63°09'N). In the shoot meristem, the cell cycle shortened to about the same extent ( 26%) in both populations exposed to the elevated [CO 2 ] treatment. In the root meristem, the cell cycle shortened by 17% in the Portuguese and by 8% in the Swedish population. However, the proportion of rapidly cycling cells increased in the Portuguese much more than in the Swedish population in both meristems. In the root meristem, there was a 1.86-fold increase in the Portuguese compared with a 1.31-fold increase in the Swedish. In the shoot meristem, the increases were 1.5-3-fold for the Portuguese and 1.2-fold for the Swedish. The data are consistent in showing that a major response to the elevated [CO 2 ] treatment was an increase in the proportion of cells that were cycling and that this was more marked for the Portuguese population. A more general response to the elevated [CO 2 ] treatment was a shortening of the cell cycle regardless of population.

  • effects of temperature and elevated co2 on cell division in shoot meristems differential responses of two natural populations of Dactylis glomerata l
    Plant Cell and Environment, 1996
    Co-Authors: E A Kinsman, M S Davies, D Francis, C Lewis, J E Young, I D Thomas, K H Chorlton, Helen J Ougham
    Abstract:

    The aim was to establish whether temperature and/or elevated [CO2] (-700 μmol mol−1) affects the cell doubling time (cdt) in the different zones of the shoot apex of two natural populations of Dactylis glomerata originating in Portugal (38° S3′ N) and in Sweden (63° 09′ N). In the Portuguese population at ambient [CO2], only the pith rib meristem (PRM) exhibited a significant shortening of cdts from 10 to 30 °C. Elevated [CO2] resulted in a significant shortening of cdt, particularly in the PRM where cdt was reduced 4-8- and 6-1-fold at 10 and 20 °C, respectively, but only 2-fold at 30 °C. In the Swedish population at ambient [CO2], there were no consistent temperature-dependent alterations to cdt and this population was less responsive to elevated [CO2] than the Portuguese population. Nevertheless, elevated [CO2] resulted in a significant shortening of the cdt for some of the zones; the maximum reduction occurred in the PRM at 30 °C. We concluded that in the shoot apex of the Portuguese population, and most notably in the PRM, 10 and 20 °C were non-optimal temperatures for cell division, whilst the Swedish population was relatively buffered against temperature change. Elevated [CO2] resulted in substantially greater reductions in cdts in the shoot meristem of the Portuguese population than in that of the Swedish population.

  • effects of temperature on cell division in root meristems of natural populations of Dactylis glomerata of contrasting latitudinal origins
    Environmental and Experimental Botany, 1993
    Co-Authors: H M C Creber, M S Davies, D Francis
    Abstract:

    Abstract The effect of temperature on cell division was studied in the root meristems of five natural populations of Dactylis glomerata from contrasting latitudes and altitudes within mainland Europe to determine which aspects of the cell cycle were most sensitive to temperature change and to what extent this was related to latitude and altitude of origin. Cell doubling times ( cdts ), and the duration of the cell cycle ( Tc were determined in primary root meristems of the five populations which were grown at 15°C for 10 days and then maintained at this temperature or transferred to either 10 or 20°C for a a further 4 days. Cdts were measured using the colchicine-metaphase arrest technique while Tcs were determined with the percentage 3 H-labelled mitoses method. The growth fraction: mean labellling index÷fraction of labelled mitoses over one cell cycle, or Tc ÷ cdt , were also calculated. The relative sensitivity of the cell cycle to lowered root temperature ( Tc 10/20) was less in populations from high latitudes/altitudes compared with populations from lower latitudes/altitudees. Growth fraction measured at all temperatures for all populations was correlated positively with the duration of the cell cycle and separately for the data at 10 and 15°C but not at 20°C. Thus, for these natural populations of Dactylis glomerata grown over a 10–20°C temperature range, the longer cell cycles were compensated for by larger growth fractions.

Xinquan Zhang - One of the best experts on this subject based on the ideXlab platform.

  • genome wide ap2 erf gene family analysis reveals the classification structure expression profiles and potential function in orchardgrass Dactylis glomerata
    Molecular Biology Reports, 2020
    Co-Authors: Guangyan Feng, Zhongfu Yang, Linkai Huang, Qingchuan Yang, Xinquan Zhang
    Abstract:

    The AP2/ERF transcription factor (TF) family is of great importance in developmental regulation and responses to stress and pathogenic stimuli. Orchardgrass (Dactylis glomerata), a perennial cold-season forage of high quality in the world's temperate zones, contributes to grazing land through mixed sowing with alfalfa (Medicago sativa) and white clover (Trifolium repens). However, little is known about AP2/ERF TFs in orchardgrass. In this study, 193 AP2/ERF genes were classified into five subfamilies and 13 subgroups through phylogenetic analysis. Chromosome structure analysis showed that AP2/ERF family genes in orchardgrass were distributed on seven chromosomes and specific conservative sequences were found in each subgroup. Exon-intron structure and motifs in the same subgroup were almost identical, and the unique motifs contributed to the classification and functional annotation of DgERFs. Expression analysis showed tissue-specific expression of DgERFs in roots and flowers, with most DgERFs widely expressed in roots. The expression levels of each subgroup (subgroups Vc, VIIa, VIIIb, IXa, and XIa) were high at the before-heading and heading stages (BH_DON and H_DON). In addition, 12 DgERFs in various tissues and five DgERFs associated with abiotic stresses were selected for qRT-PCR analysis showed that four dehydration-responsive element binding (DREB) genes and one ERF subfamily gene in orchardgrass were regulated with PEG, heat and salt stresses. DgERF056 belonged to ERF subfamily was involved in the processes of flowering and development stage. This study systematic explored the DgERFs at the genome level for the first time, which lays a foundation for a better understanding of AP2/ERF gene function in Dactylis glomerata and other types of forage.

  • integration of small rnas and transcriptome sequencing uncovers a complex regulatory network during vernalization and heading stages of orchardgrass Dactylis glomerata l
    BMC Genomics, 2018
    Co-Authors: Guangyan Feng, Wengang Xie, Zhongfu Yang, Linkai Huang, Jianping Wang, Haidong Yan, Gang Nie, Bradley S Bushman, Hao Guan, Xinquan Zhang
    Abstract:

    Flowering is a critical reproductive process in higher plants. Timing of optimal flowering depends upon the coordination among seasonal environmental cues. For cool season grasses, such as Dactylis glomerata, vernalization induced by low temperature provides competence to initiate flowering after prolonged cold. We combined analyses of the transcriptome and microRNAs (miRNAs) to generate a comprehensive resource for regulatory miRNAs and their target circuits during vernalization and heading stages. A total of 3,846 differentially expressed genes (DEGs) and 69 differentially expressed miRNAs were identified across five flowering stages. The expression of miR395, miR530, miR167, miR396, miR528, novel_42, novel_72, novel_107, and novel_123 demonstrated significant variations during vernalization. These miRNA targeted genes were involved in phytohormones, transmembrane transport, and plant morphogenesis in response to vernalization. The expression patterns of DEGs related to plant hormones, stress responses, energy metabolism, and signal transduction changed significantly in the transition from vegetative to reproductive phases. Five hub genes, c136110_g1 (BRI1), c131375_g1 (BZR1), c133350_g1 (VRN1), c139830_g1 (VIN3), and c125792_g2 (FT), might play central roles in vernalization response. Our comprehensive analyses have provided a useful platform for investigating consecutive transcriptional and post-transcriptional regulation of critical phases in D. glomerata and provided insights into the genetic engineering of flowering-control in cereal crops.

  • Comprehensive transcriptome analysis reveals distinct regulatory programs during vernalization and floral bud development of orchardgrass ( Dactylis glomerata L.)
    BMC Plant Biology, 2017
    Co-Authors: Guangyan Feng, Linkai Huang, Jianping Wang, Ling Pan, Xinxin Zhao, Xia Wang, Huang Ting, Xinquan Zhang
    Abstract:

    Vernalization and the transition from vegetative to reproductive growth involve multiple pathways, vital for controlling floral organ formation and flowering time. However, little transcription information is available about the mechanisms behind environmental adaption and growth regulation. Here, we used high-throughput sequencing to analyze the comprehensive transcriptome of Dactylis glomerata L. during six different growth periods. During vernalization, 4689 differentially expressed genes (DEGs) significantly increased in abundance, while 3841 decreased. Furthermore, 12,967 DEGs were identified during booting stage and flowering stage, including 7750 up-regulated and 5219 down-regulated DEGs. Pathway analysis indicated that transcripts related to circadian rhythm, photoperiod, photosynthesis, flavonoid biosynthesis, starch, and sucrose metabolism changed significantly at different stages. Coexpression and weighted correlation network analysis (WGCNA) analysis linked different stages to transcriptional changes and provided evidence of inner relation modules associated with signal transduction, stress responses, cell division, and hormonal transport. We found enrichment in transcription factors (TFs) related to WRKY, NAC, AP2/EREBP, AUX/IAA, MADS-BOX, ABI3/VP1, bHLH, and the CCAAT family during vernalization and floral bud development. TFs expression patterns revealed intricate temporal variations, suggesting relatively separate regulatory programs of TF modules. Further study will unlock insights into the ability of the circadian rhythm and photoperiod to regulate vernalization and flowering time in perennial grass.

  • genetic diversity and association of est ssr and scot markers with rust traits in orchardgrass Dactylis glomerata l
    Molecules, 2016
    Co-Authors: Haidong Yan, Bing Zeng, Xinquan Zhang, Yan Peng, Linkai Huang, Yu Zhang, Guohua Yin, Xiaomei Jiang, Xinchun Liu, Yanhong Yan
    Abstract:

    Orchardgrass (Dactylis glomerata L.), is a well-known perennial forage species; however, rust diseases have caused a noticeable reduction in the quality and production of orchardgrass. In this study, genetic diversity was assessed and the marker-trait associations for rust were examined using 18 EST-SSR and 21 SCoT markers in 75 orchardgrass accessions. A high level of genetic diversity was detected in orchardgrass with an average genetic diversity index of 0.369. For the EST-SSR and SCoT markers, 164 and 289 total bands were obtained, of which 148 (90.24%) and 272 (94.12%) were polymorphic, respectively. Results from an AMOVA analysis showed that more genetic variance existed within populations (87.57%) than among populations (12.43%). Using a parameter marker index, the efficiencies of the EST-SSR and SCoT markers were compared to show that SCoTs have higher marker efficiency (8.07) than EST-SSRs (4.82). The results of a UPGMA cluster analysis and a STRUCTURE analysis were both correlated with the geographic distribution of the orchardgrass accessions. Linkage disequilibrium analysis revealed an average r² of 0.1627 across all band pairs, indicating a high extent of linkage disequilibrium in the material. An association analysis between the rust trait and 410 bands from the EST-SSR and SCoT markers using TASSEL software revealed 20 band panels were associated with the rust trait in both 2011 and 2012. The 20 bands obtained from association analysis could be used in breeding programs for lineage selection to prevent great losses of orchardgrass caused by rust, and provide valuable information for further association mapping using this collection of orchardgrass.

  • identifying differentially expressed genes under heat stress and developing molecular markers in orchardgrass Dactylis glomerata l through transcriptome analysis
    Molecular Ecology Resources, 2015
    Co-Authors: Linkai Huang, Xinquan Zhang, Haidong Yan, Guohua Yin, X X Zhao, J Wang, Taylor P Frazier, Xiu Huang, D F Yan, W J Zang
    Abstract:

    Orchardgrass (Dactylis glomerata L.) is a long-lived, cool-season forage grass that is commonly used for hay production. Despite its economic importance, orchardgrass genome remains relatively unexplored. In this study, we used Illumina RNA sequencing to identify gene-associated molecular markers, including simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs), as well as heat stress-induced differentially expressed genes (DEGs) in two orchardgrass genotypes, 'Baoxing' (heat resistant) and '01998' (heat susceptible). Approximately 163 million high-quality trimmed reads were generated from 207 million raw reads using the Illumina HiSeq 2000 platform. A total of 126,846 unigenes were obtained after de novo assembly of the trimmed reads, and 40,078 unigenes were identified as coding sequences (CDSs). Based on the assembled unigenes, 669,300 high-quality SNPs, including 416,099 transitions and 257,736 transversions, were contained in 75,875 unigenes. In addition, a total of 8475 microsatellites were detected in 7764 unigenes. When placed under heat stress, the total number of DEGs in 'Baoxing' (3527) was higher than in '01998' (2649), indicating that in comparison with heat-susceptible '01998', heat-resistant 'Baoxing' seems to have more unigenes that respond to heat stress. The high-throughput transcriptome sequencing of orchardgrass under heat stress provides useful information for gene identification and for the development of SNP and SSR molecular markers. The comparison of DEGs under different periods of heat stress allowed us to identify a wealth of candidate DEGs that can be further analysed in order to determine the genetic mechanisms underlying heat tolerance in orchardgrass.

Helen J Ougham - One of the best experts on this subject based on the ideXlab platform.

  • elevated co2 stimulates cells to divide in grass meristems a differential effect in two natural populations of Dactylis glomerata
    Plant Cell and Environment, 1997
    Co-Authors: E A Kinsman, M S Davies, D Francis, C Lewis, J E Young, B Vilhar, Helen J Ougham
    Abstract:

    In this study, we tested the hypothesis that elevated [CO 2 ] shortens the cell cycle in meristems of Dactylis glomerata, more in a Portuguese population (38°53'N) than in a Swedish population (63°09'N). In the shoot meristem, the cell cycle shortened to about the same extent ( 26%) in both populations exposed to the elevated [CO 2 ] treatment. In the root meristem, the cell cycle shortened by 17% in the Portuguese and by 8% in the Swedish population. However, the proportion of rapidly cycling cells increased in the Portuguese much more than in the Swedish population in both meristems. In the root meristem, there was a 1.86-fold increase in the Portuguese compared with a 1.31-fold increase in the Swedish. In the shoot meristem, the increases were 1.5-3-fold for the Portuguese and 1.2-fold for the Swedish. The data are consistent in showing that a major response to the elevated [CO 2 ] treatment was an increase in the proportion of cells that were cycling and that this was more marked for the Portuguese population. A more general response to the elevated [CO 2 ] treatment was a shortening of the cell cycle regardless of population.

  • effects of temperature and elevated co2 on cell division in shoot meristems differential responses of two natural populations of Dactylis glomerata l
    Plant Cell and Environment, 1996
    Co-Authors: E A Kinsman, M S Davies, D Francis, C Lewis, J E Young, I D Thomas, K H Chorlton, Helen J Ougham
    Abstract:

    The aim was to establish whether temperature and/or elevated [CO2] (-700 μmol mol−1) affects the cell doubling time (cdt) in the different zones of the shoot apex of two natural populations of Dactylis glomerata originating in Portugal (38° S3′ N) and in Sweden (63° 09′ N). In the Portuguese population at ambient [CO2], only the pith rib meristem (PRM) exhibited a significant shortening of cdts from 10 to 30 °C. Elevated [CO2] resulted in a significant shortening of cdt, particularly in the PRM where cdt was reduced 4-8- and 6-1-fold at 10 and 20 °C, respectively, but only 2-fold at 30 °C. In the Swedish population at ambient [CO2], there were no consistent temperature-dependent alterations to cdt and this population was less responsive to elevated [CO2] than the Portuguese population. Nevertheless, elevated [CO2] resulted in a significant shortening of the cdt for some of the zones; the maximum reduction occurred in the PRM at 30 °C. We concluded that in the shoot apex of the Portuguese population, and most notably in the PRM, 10 and 20 °C were non-optimal temperatures for cell division, whilst the Swedish population was relatively buffered against temperature change. Elevated [CO2] resulted in substantially greater reductions in cdts in the shoot meristem of the Portuguese population than in that of the Swedish population.