The Experts below are selected from a list of 22131 Experts worldwide ranked by ideXlab platform

Sylvain Delzon - One of the best experts on this subject based on the ideXlab platform.

  • vulnerability to xylem embolism as a major correlate of the environmental distribution of rain forest species on a tropical island
    Plant Cell and Environment, 2017
    Co-Authors: Santiago Trueba, Robin Pouteau, Frederic Lens, Taylor S Feild, Sandrine Isnard, Mark E Olson, Sylvain Delzon
    Abstract:

    : Increases in drought-induced tree mortality are being observed in tropical rain forests worldwide and are also likely to affect the geographical distribution of tropical vegetation. However, the mechanisms underlying the drought vulnerability and environmental distribution of tropical species have been little studied. We measured vulnerability to xylem embolism (P50 ) of 13 woody species endemic to New Caledonia and with different xylem conduit morphologies. We examined the relation between P50 , along with other leaf and xylem functional Traits, and a range of habitat variables. Selected species had P50 values ranging between -4.03 and -2.00 MPa with most species falling in a narrow range of resistance to embolism above -2.7 MPa. Embolism vulnerability was significantly correlated with elevation, mean annual temperature and percentage of species occurrences located in rain forest habitats. Xylem conduit type did not explain variation in P50 . Commonly used functional Traits such as wood density and leaf Traits were not related to embolism vulnerability. Xylem embolism vulnerability stands out among other commonly used functional Traits as a major driver of species environmental distribution. Drought-induced xylem embolism vulnerability behaves as a Physiological Trait closely associated with the habitat occupation of rain forest woody species.

  • is sensitivity to xylem cavitation a relevant Physiological Trait for fodder production in dry season
    The role of functional diversity for ecosystem services in multi-functional agroforestry FUNCITREE final conference Trondheim 23-25 May 2013 : Book of, 2013
    Co-Authors: Philippe Thaler, Ariane Cosiaux, Sylvain Delzon, Mayecor Diouf
    Abstract:

    In the Sahel parklands, trees can provide fodder during the dry season if they keep functional foliage. In such conditions, the xylem vessels sustain high tension which can induce cavitation, decrease the conduction of sap and lead to branch mortality. Therefore, xylem resistance to cavitation is a good index of tree tolerance to water stress. However, information about this parameter remains scarce in Sahel tree species. Moreover, its measurement is difficult and requires equipment limiting its feasibility in field conditions. To measure the vulnerability to xylem cavitation in 10 tree species with fodder potential in North Senegal and to assess if this ecoPhysiological Trait can be correlated to morphological Traits that are easier to measures: wood density, xylem anatomy, and vessel length. Branch samples were collected in parklands in Louga region, Northern Senegal. Wood density and xylem anatomy were determined. Branch sections were wrapped to keep wet and sent to France within 1 week. The Cavitron spinning technique was used to construct cavitation vulnerability curves and to compute the P50 (water potential inducing 50 % loss of conductivity). Vessel length was assessed by flushing air at low pressure through gradually shortened branch sections. The Cavitron spinning technique was not relevant on nine out of ten species. Most vulnerability curves had a sharp increase in loss of conductivity, starting at low water stress. The resulting P50 which were not consistent with water potential measured in the field. All this species but Tamarindus indica had xylem elements longer than the device rotor. They were severed during measurement, inducing artificial loss of conductivity. Only Boscia senegalensis showed correct curves, and revealed very resistant to cavitation (P50 = ?7.9 Mpa). Wood densities ranged between 0.41 - Adansonia digitata - to 0.71 - Acacia tortilis. P50 estimated from these densities were between - 2 and - 6 MPa. Vulnerability to xylem cavitation could not be assessed by the spinning technique 'Cavitron', due to long xylem vessels elements in most the species. The probable low vulnerabilities estimated from high wood densities could be corroborated by xylem anatomy. (Texte integral)

Erick Amombo - One of the best experts on this subject based on the ideXlab platform.

  • screening of diverse tall fescue population for salinity tolerance based on ssr marker Physiological Trait association
    Euphytica, 2018
    Co-Authors: Erick Amombo, Guangyang Wang, Shugao Fan, An Shao, Yinkun Zhang
    Abstract:

    Soil salinity is a notorious abiotic stress which constrains plant growth and limits crop productivity. Recent advances in phytogenetics especially the discovery of marker-Trait association have facilitated the efficient selection of stress-tolerant crops. The objective of this study was to evaluate tall fescue (Festuca arundinacea Schreb.) accessions growing under salt stress in order to identify salt-tolerant and salt-sensitive genotypes using Physiological and molecular markers. The population consisted of 114 diverse tall fescue accessions which were assessed using 99 simple sequence repeat (SSR) markers and five functional Physiological Traits i.e., turf quality, leaf water content, chlorophyll content, relative growth rate, and evapotranspiration rate. Salinity stress induced great variations among the functional Physiological Traits and there were significant correlations among them. The population structure analysis revealed two distinct populations, while association mapping between the SSRs and phenotypic Traits identified significant associations. In addition, the accessions that maintained relatively higher Physiological Traits had a significantly lower accumulation of Na+ and Cl− in the roots compared to those whose functional Traits declined. We identified six most salt-tolerant accessions due to their high values of Physiological parameters and significantly low accumulation of Na+ and Cl− in the roots. Similarly, we identified six accessions we considered to be most salt-sensitive as observed by high Na+ and Cl− accumulation plus a decline in the Physiological activities. Our findings are helpful to tall fescue breeders with a goal of producing tall fescue cultivars with enhanced salt tolerance.

  • comparative study of diversity based on heat tolerant related morpho Physiological Traits and molecular markers in tall fescue accessions
    Scientific Reports, 2015
    Co-Authors: Xiaoyan Sun, Yan Xie, Jianping Liu, Erick Amombo
    Abstract:

    Heat stress is a critical challenge to tall fescue (Festuca arundinacea Schreb.) in many areas of the globe and variations in genetic structure and functional Traits is for the efficient breeding programs on developing heat tolerant cultivars. Tolerant-related morpho-Physiological Traits and simple sequence repeat (SSR) markers were employed to survey genetic diversity in greenhouse and growth chamber trials. 100 tall fescue accessions, including 8 commercial cultivars and 92 natural genotypes, showed a high variation in phenotypic performance under heat stress. Based on standardized heat tolerant-related morpho-Physiological data, all tall fescue accessions were clustered into five groups. The accessions with similar heat tolerance were likely to be clustered in the same group. The highest genetic diversity was obtained for accessions from Africa judged by Nei’s gene diversity (0.2640) and PIC (0.2112). All grass accessions could be divided into three major groups based on SSR markers, which was partially congruous to the geographical regions and history of introduction. A low correlation was found between morpho-Physiological Traits and SSR markers by Mantel test. The patterns in morpho-Physiological Trait variations and genetic diversity associated with heat tolerance were useful to design breeding programs for developing heat stress resistance in tall fescue.

Franck Bertolla - One of the best experts on this subject based on the ideXlab platform.

  • Natural transformation in the Ralstonia solanacearum species complex: number and size of DNA that can be transferred.
    FEMS microbiology ecology, 2008
    Co-Authors: Bénédicte Coupat, Xavier Nesme, Pascal Simonet, Fanny Chaumeille-dole, Saliou Fall, Philippe Prior, Franck Bertolla
    Abstract:

    Ralstonia solanacearum is a widely distributed phytopathogenic bacterium that is known to invade more than 200 host species, mainly in tropical areas. Reference strain GMI1000 is naturally transformable at in vitro and also in planta conditions and thus has the ability to acquire free exogenous DNA. We tested the ubiquity and variability of natural transformation in the four phylotypes of this species complex using 55 strains isolated from different hosts and geographical regions. Eighty per cent of strains distributed in all the phylotypes were naturally transformable by plasmids and/or genomic DNA. Transformability can be considered as a ubiquitous Physiological Trait in the R. solanacearum species complex. Transformation performed with two independent DNA donors showed that multiple integration events occurred simultaneously in two distant genomic regions. We also engineered a fourfold-resistant R. solanacearum GMI1000 mutant RS28 to evaluate the size of DNA exchanged during natural transformation. The results demonstrated that this bacterium was able to exchange large DNA fragments ranging from 30 to 90 kb by DNA replacement. The combination of these findings indicated that the natural transformation mechanism could be the main driving force of genetic diversification of the R. solanacearum species complex.

  • Natural transformation in the Ralstonia solanacearum species complex: numberand size of DNA that can be transferred
    FEMS Microbiology Ecology, 2008
    Co-Authors: Bénédicte Coupat, Xavier Nesme, Pascal Simonet, Fanny Chaumeille-dole, Saliou Fall, Philippe Prior, Franck Bertolla
    Abstract:

    Ralstonia solanacearum is a widely distributed phytopathogenic bacterium that is known to invade more than 200 host species, mainly in tropical areas. Reference strain GMI1000 is naturally transformable at in vitro and also in planta conditions and thus has the ability to acquire free exogenous DNA.We tested the ubiquity and variability of natural transformation in the four phylotypes of this species complex using 55 strains isolated from different hosts and geographical regions. Eighty per cent of strains distributed in all the phylotypes were naturally transformable by plasmids and/or genomic DNA. Transformability can be considered as a ubiquitous Physiological Trait in the R. solanacearum species complex. Transformation performed with two independent DNA donors showed that multiple integration events occurred simultaneously in two distant genomic regions. We also engineered a fourfold-resistant R. solanacearum GMI1000 mutant RS28 to evaluate the size of DNA exchanged during natural transformation. The results demonstrated that this bacterium was able to exchange large DNA fragments ranging from 30 to 90 kb by DNA replacement. The combination of these findings indicated that the natural transformation mechanism could be the main driving force of genetic diversification of the R. solanacearum species complex.

Kent E Holsinger - One of the best experts on this subject based on the ideXlab platform.

  • intraspecific Trait variation influences Physiological performance and fitness in the south africa shrub genus protea proteaceae
    Annals of Botany, 2021
    Co-Authors: Kristen M Nolting, Rachel Prunier, Guy F Midgley, Kent E Holsinger
    Abstract:

    BACKGROUND AND AIMS Global plant Trait datasets commonly identify Trait relationships that are interpreted to reflect fundamental trade-offs associated with plant strategies, but often these Trait relationships are not identified when evaluating them at smaller taxonomic and spatial scales. In this study we evaluate Trait relationships measured on individual plants for five widespread Protea species in South Africa to determine whether broad-scale patterns of structural Trait (e.g. leaf area) and Physiological Trait (e.g. photosynthetic rates) relationships can be detected within natural populations, and if these Traits are themselves related to plant fitness. METHODS We evaluated the variance structure (i.e. the proportional intraspecific Trait variation relative to among-species variation) for nine structural Traits and six Physiological Traits measured in wild populations. We used a multivariate path model to evaluate the relationships between structural Traits and Physiological Traits, and the relationship between these Traits and plant size and reproductive effort. KEY RESULTS While intraspecific Trait variation is relatively low for structural Traits, it accounts for between 50 and 100 % of the variation in Physiological Traits. Furthermore, we identified few Trait associations between any one structural Trait and Physiological Trait, but multivariate regressions revealed clear associations between combinations of structural Traits and Physiological performance (R2 = 0.37-0.64), and almost all Traits had detectable associations with plant fitness. CONCLUSIONS Intraspecific variation in structural Traits leads to predictable differences in individual-level Physiological performance in a multivariate framework, even though the relationship of any particular structural Trait to Physiological performance may be weak or undetectable. Furthermore, intraspecific variation in both structural and Physiological Traits leads to differences in plant size and fitness. These results demonstrate the importance of considering measurements of multivariate phenotypes on individual plants when evaluating Trait relationships and how Trait variation influences predictions of ecological and evolutionary outcomes.

  • intraspecific Trait variation influences Physiological performance and fitness in the south africa shrub genus protea proteaceae
    Annals of Botany, 2020
    Co-Authors: Kristen M Nolting, Rachel Prunier, Guy F Midgley, Kent E Holsinger
    Abstract:

    BACKGROUND AND AIMS: Global plant Trait datasets commonly identify Trait relationships that are interpreted to reflect fundamental trade-offs associated with plant strategies, but often these Trait relationships are not identified when evaluating them at smaller taxonomic and spatial scales. In this study we evaluate Trait relationships measured on individual plants for five widespread Protea species in South Africa to determine whether broad scale patterns of structural Trait (e.g. leaf area) and Physiological Trait (e.g. photosynthetic rates) relationships can be detected within natural populations, and if these Traits are themselves related to plant fitness. METHODS: We evaluated the variance structure (i.e. the proportional intraspecific Trait variation relative to among species variation) for nine structural Traits and the six Physiological Traits measured in wild populations. We used a multivariate path model to evaluate the relationships between structural Traits and Physiological Traits, and the relationship between these Traits and plant size and reproductive effort. KEY RESULTS: While intraspecific Trait variation is relatively low for structural Traits, it accounts for between 50-100% of the variation in Physiological Traits. Further, we identified few Trait associations between any one structural Trait and Physiological Trait, but multivariate regressions reveal clear associations between combinations of structural Traits and Physiological performance (R2 of 0.37-0.64), and almost all Traits had detectable associations with plant fitness. CONCLUSIONS: Intraspecific variation in structural Traits leads to predictable differences in individual-level Physiological performance in a multivariate framework, even though the relationship of any particular structural Trait to Physiological performance may be weak or undetectable. Furthermore, intraspecific variation in both structural and Physiological Traits leads to differences in plant size and fitness. These results demonstrate the importance of considering measurements of multivariate phenotypes on individual plants when evaluating Trait relationships and how Trait variation influences predictions of ecological and evolutionary outcomes.

Lourens Poorter - One of the best experts on this subject based on the ideXlab platform.

  • light dependent changes in the relationship between seed mass and seedling Traits a meta analysis for rain forest tree species
    Oecologia, 2005
    Co-Authors: Lourens Poorter, Simmone A Rose
    Abstract:

    Seed mass is considered to be an important attribute for the establishment success of plant species being linked with their seed production, establishment, and survival. This meta-analysis shows that seed mass is also closely correlated to growth-related species attributes of the established phase of rain forest tree species, and that the strength of this relationship varies with light conditions. Seed mass is an especially good predictor of species Traits under high-light conditions, when the species attain their full growth potential. At high irradiance (>20% of full light) seed mass is negatively correlated with RGR, NAR, LAR, SLA and LMF. At low irradiance (<5% of full light), seed mass is only negatively correlated with LAR and SLA. Correlations between seed mass and morphological Traits are therefore strongest at low irradiance where light interception is important. Conversely, correlations between seed mass and a Physiological Trait are strongest at high irradiance, where maximisation of photosynthetic rates is important. The strength of the correlation between growth parameters and seed mass declines over time, and disappears after 1–4 years. Seed mass appears to be a good proxy for the shade tolerance of tropical tree species, especially at the younger stages of the life cycle.

  • growth responses of 15 rain forest tree species to a light gradient the relative importance of morphological and Physiological Traits
    Functional Ecology, 1999
    Co-Authors: Lourens Poorter
    Abstract:

    1. Growth of seedlings of 15 rain-forest tree species was compared under controlled conditions, at six different light levels (3, 6, 12, 25, 50 and 100% daylight). 2. Most plant variables showed strong ontogenetic changes; they were highly dependent on the biomass of the plant. 3. Growth rate was highest at intermediate light levels (25–50%) above which it declined. Most plant variables showed a curvilinear response to irradiance, with the largest changes at the lowest light levels. 4. There was a consistent ranking in growth between species; species that were fast growing in a low-light environment were also fast growing in a high-light environment. 5. At low light, interspecific variation in relative growth rate was determined mainly by differences in a morphological Trait, the leaf area ratio (LAR), whereas at high light it was determined mainly by differences in a Physiological Trait, the net assimilation rate (NAR). 6. NAR became a stronger determinant of growth than LAR in more than 10–15% daylight. As light availability in the forest is generally much lower than this threshold level, it follows that interspecific variation in growth in a forest environment is mainly owing to variation in morphology.