The disaccharide trehalose is involved in stress response in many organisms. However, in plants, its precise role remains unclear, although some data indicate that trehalose has a protective role ...during abiotic stresses. By contrast, some trehalose metabolism mutants exhibit growth aberrations, revealing potential negative effects on plant physiology. Contradictory effects also appear under biotic stress conditions. Specifically, trehalose is essential for the infectivity of several pathogens but at the same time elicits plant defense. Here, we argue that trehalose should not be regarded only as a protective sugar but rather like a double-faced molecule and that further investigation is required to elucidate its exact role in stress tolerance in plants.
The roles of two cytosolic maize glutamine synthetase isoenzymes (GS1), products of the Gln1-3 and Gln1-4 genes, were investigated by examining the impact of knockout mutations on kernel yield. In ...the gln1-3 and gln1-4 single mutants and the gln1-3 gln1-4 double mutant, GS mRNA expression was impaired, resulting in reduced GS1 protein and activity. The gln1-4 phenotype displayed reduced kernel size and gln1-3 reduced kernel number, with both phenotypes displayed in gln1-3 gln1-4. However, at maturity, shoot biomass production was not modified in either the single mutants or double mutants, suggesting a specific impact on grain production in both mutants. Asn increased in the leaves of the mutants during grain filling, indicating that it probably accumulates to circumvent ammonium buildup resulting from lower GS1 activity. Phloem sap analysis revealed that unlike Gln, Asn is not efficiently transported to developing kernels, apparently causing reduced kernel production. When Gln1-3 was overexpressed constitutively in leaves, kernel number increased by 30%, providing further evidence that GS1-3 plays a major role in kernel yield. Cytoimmunochemistry and in situ hybridization revealed that GS1-3 is present in mesophyll cells, whereas GS1-4 is specifically localized in the bundle sheath cells. The two GS1 isoenzymes play nonredundant roles with respect to their tissue-specific localization.
•Miscanthus biomass production and composition traits were not always synergistic.•The relationships between these traits were consistent over years and harvest dates.•The leaves and the stems ...contributed differently to the biomass composition.•Biomass production traits were mainly influenced by year of cultivation or clone.•Biomass composition traits were mainly influenced by harvest date.
The perennial miscanthus crop is a promising feedstock for cellulosic ethanol production due to its high yield, low input and low environmental impacts. To be suitable for cellulosic ethanol production, cultivated Miscanthus clones need to present not only high aboveground biomass production, but also high cellulose and hemicellulose contents and low lignin, soluble, and ash contents. By testing M.×giganteus, M. sacchariflorus, and M. sinensis clones, we investigated the relationships between biomass production and biomass composition traits at two harvest dates over 3 years. High aboveground biomass production was associated with high canopy height, high stem diameter, late flowering, and high cellulose and lignin contents but low hemicellulose, soluble, and ash contents. The aboveground biomass production was positively correlated with the potential yields of cellulose, hemicelluloses, and lignins. These relationships were consistent throughout the years and the harvest dates. The most productive Miscanthus clones displayed high cellulose contents and low soluble and ash contents; however, they displayed low hemicellulose contents and high lignin contents. The total aboveground biomass composition was closer to the stem composition than to the leaf composition. Nevertheless, the leaves were interesting because of their high hemicellulose and low lignin contents. Lastly, all of the studied factors were significant, but the biomass production traits were mainly affected by the year of cultivation or clone, while the biomass composition traits were mainly affected by the harvest date. All of the traits showed low interaction effects. These results will guide the breeding of Miscanthus clones that are tailored for biofuel production.
Trehalose is a non‐reducing disaccharide involved in stress tolerance in plants. To understand better the role of trehalose in the osmotic stress response in linseed (Linum usitatissimum), trehalose ...content in leaves was studied. First, the method commonly used for sugar determination, high performance anion exchange chromatography with pulsed amperometric detection (HPAEC‐PAD), gave unsatisfactory results and the separation efficiency could not be improved by varying the elution conditions. The same problem was also found in the model plant: Arabidopsis thaliana. After clearly highlighting a co‐elution of trehalose in these two species by a trehalase assay and liquid chromatography‐high resolution mass spectrometry analysis, gas chromatography–mass spectrometry (GC‐MS) was used as the analytical method instead. These results confirmed that trehalose content is currently overestimated by HPAEC‐PAD analysis, approximately 7 and 13 times for A. thaliana and linseed respectively. Thus GC‐MS gave more satisfactory results for trehalose quantification in plants. With this method, trehalose accumulation was observed in linseed during an osmotic stress (−0.30 MPa), the quantity (31.49 nmol g–1 dry weight after 48 h) appears too low to assign an osmoprotector or osmoregulator role to trehalose in stressed linseed.
An understanding of the genetic determinism of frost tolerance is a prerequisite for the development of frost tolerant cultivars for cold northern areas. In legumes, it is not known to which extent ...vernalization requirement or photoperiod responsiveness are necessary for the development of frost tolerance. In pea (Pisum sativum L.) however, the flowering locus Hr is suspected to influence winter frost tolerance by delaying floral initiation until after the main winter freezing periods have passed. The objective of this study was to dissect the genetic determinism of frost tolerance in pea by QTL analysis and to assess the genetic linkage between winter frost tolerance and the Hr locus. A population of 164 recombinant inbred lines (RILs), derived from the cross Champagne x Terese was evaluated both in the greenhouse and in field conditions to characterize the photoperiod response from which the allele at the Hr locus was inferred. In addition, the population was also assessed for winter frost tolerance in 11 field conditions. Six QTL were detected, among which three were consistent among the different experimental conditions, confirming an oligogenic determinism of frost tolerance in pea. The Hr locus was found to be the peak marker for the highest explanatory QTL of this study. This result supports the hypothesis of the prominent part played by the photoperiod responsiveness in the determinism of frost tolerance for this species. The consistency of three QTL makes these positions interesting targets for marker-assisted selection.
To develop the perennial grass
Miscanthus x giganteus
as a highly productive crop for biomass production, new varieties need to be bred, and more knowledge about its growth behaviour has to be ...collected. Our aim was to identify an efficient function for assessing and comparing emergence date and canopy height growth (rate, duration, and final maximal height) of 21 clones of Miscanthus in Northern France. Flow cytometry made it possible to classify the clones into three clusters corresponding to 2x, 3x, and 4x ploidy levels. Three functions, 3- and 4-parameter logistic functions and Gompertz function, were tested to best describe the dynamics of crop emergence and of plant growth. The best functions were used to estimate emergence dynamics (Gompertz function), and growth dynamics (4-parameter logistic). All these traits showed a significant year, clone, and corresponding interaction effects (but not for harvest date). Species and ploidy level explained the clone and clone × year interaction effects.
M. x giganteus
and
M. floridulus
clones were among the latest to emerge, and the tallest.
M. sinensis
clones showed the lowest height and growth rates. Higher final canopy height was correlated to late emergence and high growth rate. These findings could help early selection of interesting clones within
M. sinensis
populations, in order to breed new inter-species hybrids of
giganteus
type.
It is important for breeders and producers to be aware of competition effects for variety trials. We aimed at developing an index of competition to reduce statistical variability in field trials and ...improve comparisons between genotypes of Miscanthus. Twenty-one clones belonging to four species of
Miscanthus
(
M. x giganteus
,
M. floridulus
,
M. sinensis
, and
M. sacchariflorus
) planted at the same density were compared at two harvest dates during the second and third crop years. Aboveground volume was shown to be a good predictor of the aboveground biomass of the clones, and was analysed for the competition effect. The best competition index was the ground area occupied by the eight neighbour plants, among the four indices defined as covariates in the statistical models. It reduced the root mean square error of the aboveground volume by as much as 17 %, explaining up to 36 % of the residual error of the model. Our results then concerned the contribution of intragenotypic competition of Miscanthus to the variability between plants of a same clone during field trials, the relationship between competition ability and plant traits, and the comparison of genotypes regarding this competition. All clones showed negative competition sensitivities depending on harvest date, crop year, and clone. The competition effects lead to reduction in mean aboveground volume by up to 17 %. Competition sensitivities were strongly correlated with aboveground development (height and yield) in both crop years, whatever the harvest dates. In Miscanthus field trials, using a competition index may help to reduce statistical variability and improve comparisons between genotypes.
It is important for breeders and producers to be aware of competition effects for variety trials. We aimed at developing an index of competition to reduce statistical variability in field trials and ...improve comparisons between genotypes of Miscanthus. Twenty-one clones belonging to four species of Miscanthus (M. x giganteus, M. floridulus, M. sinensis, and M. sacchariflorus) planted at the same density were compared at two harvest dates during the second and third crop years. Aboveground volume was shown to be a good predictor of the aboveground biomass of the clones, and was analysed for the competition effect. The best competition index was the ground area occupied by the eight neighbour plants, among the four indices defined as covariates in the statistical models. It reduced the root mean square error of the aboveground volume by as much as 17 %, explaining up to 36 % of the residual error of the model. Our results then concerned the contribution of intra- genotypic competition of Miscanthus to the variability between plants of a same clone during field trials, the relationship between competition ability and plant traits, and the comparison of genotypes regarding this competition. All clones showed negative competition sensitivities depending on harvest date, crop year, and clone. The competition effects lead to reduction in mean aboveground volume by up to 17 %. Competition sensitivities were strongly correlated with aboveground development (height and yield) in both crop years, whatever the harvest dates. In Miscanthus field trials, using a competition index may help to reduce statistical variability and improve comparisons between genotypes.
It is important for breeders and producers to be aware of competition effects for variety trials. We aimed at developing an index of competition to reduce statistical variability in field trials and ...improve comparisons between genotypes of Miscanthus. Twenty-one clones belonging to four species of Miscanthus (M. x giganteus, M. floridulus, M. sinensis, and M. sacchariflorus) planted at the same density were compared at two harvest dates during the second and third crop years. Aboveground volume was shown to be a good predictor of the aboveground biomass of the clones, and was analysed for the competition effect. The best competition index was the ground area occupied by the eight neighbour plants, among the four indices defined as covariates in the statistical models. It reduced the root mean square error of the aboveground volume by as much as 17 %, explaining up to 36 % of the residual error of the model. Our results then concerned the contribution of intra- genotypic competition of Miscanthus to the variability between plants of a same clone during field trials, the relationship between competition ability and plant traits, and the comparison of genotypes regarding this competition. All clones showed negative competition sensitivities depending on harvest date, crop year, and clone. The competition effects lead to reduction in mean aboveground volume by up to 17 %. Competition sensitivities were strongly correlated with aboveground development (height and yield) in both crop years, whatever the harvest dates. In Miscanthus field trials, using a competition index may help to reduce statistical variability and improve comparisons between genotypes.
An index of competition reduces statistical variability and improves comparisons between genotypes of Miscanthus Zub , Hélène (INRA , Peronne (France). UMR 1281 Stress Abiotiques et Différenciation des Végétaux Cultivés); Monod , Herve (INRA , Jouy-En-Josas (France). UR 0341 Unité de recherche Mathématiques et Informatique Appliquées); Bethencourt , Linda (INRA , Peronne (France). UMR 1281 Stress Abiotiques et Différenciation des Végétaux Cultivés) ...
2012
Publication
It is important for breeders and producers to be aware of competition effects for variety trials. We aimed at developing an index of competition to reduce statistical variability in field trials and ...improve comparisons between genotypes of Miscanthus. Twenty-one clones belonging to four species of Miscanthus (M. x giganteus, M. floridulus, M. sinensis, and M. sacchariflorus) planted at the same density were compared at two harvest dates during the second and third crop years. Aboveground volume was shown to be a good predictor of the aboveground biomass of the clones, and was analysed for the competition effect. The best competition index was the ground area occupied by the eight neighbour plants, among the four indices defined as covariates in the statistical models. It reduced the root mean square error of the aboveground volume by as much as 17 %, explaining up to 36 % of the residual error of the model. Our results then concerned the contribution of intra- genotypic competition of Miscanthus to the variability between plants of a same clone during field trials, the relationship between competition ability and plant traits, and the comparison of genotypes regarding this competition. All clones showed negative competition sensitivities depending on harvest date, crop year, and clone. The competition effects lead to reduction in mean aboveground volume by up to 17 %. Competition sensitivities were strongly correlated with aboveground development (height and yield) in both crop years, whatever the harvest dates. In Miscanthus field trials, using a competition index may help to reduce statistical variability and improve comparisons between genotypes.
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