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Abdelkader Aïnouche

Bio: Abdelkader Aïnouche is an academic researcher from University of Rennes. The author has contributed to research in topics: Phylogenetic tree & Lupinus. The author has an hindex of 21, co-authored 43 publications receiving 1448 citations. Previous affiliations of Abdelkader Aïnouche include University of Alberta & Centre national de la recherche scientifique.

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TL;DR: The results strongly suggest the loss of one GBSSI duplicated copy (GBSSI-1) in the Fragariinae subtribe, and a new pattern summarizing the present knowledge on the Fragaria evolutionary history is proposed.

169 citations

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TL;DR: The compatible solute hypothesis as mentioned in this paper posits that maintaining osmotic equilibrium under conditions of high salinity requires synthesis of organic compounds, uptake of potassium ions, and partial exclusion of NaCl.
Abstract: The compatible solute hypothesis posits that maintaining osmotic equilibrium under conditions of high salinity requires synthesis of organic compounds, uptake of potassium ions, and partial exclusion of NaCl. To assess whether osmotic adaptation in Limonium latifolium proceeds according to this hypothesis, a comprehensive analysis of solute accumulation during NaCl treatments was conducted. Determination of prevailing inorganic ions and establishment of the metabolic profiles for low M(r) organic substances revealed that contrary to the mentioned hypothesis the major contributors to osmolarity were constituted by inorganic solutes. Independent of salinity, only 25% of this osmolarity resulted from organic solutes such as Suc and hexoses. Proline (Pro), beta-alanine betaine, and choline-O-sulfate were minor contributors to osmolarity. Compatible inositols also occurred, especially chiro-inositol, characterized for the first time in this species, to our knowledge. Principal component analysis showed that only a limited number of metabolic reconfigurations occurred in response to dynamic changes in salinity. Under such conditions only sugars, chiro-inositol, and Pro behave as active osmobalancers. Analysis of metabolic profiles during acclimatization to either mild salinity or nonsaline conditions showed that organic solute accumulation is predominantly controlled by constitutive developmental programs, some of which might be slightly modulated by salinity. Osmolarity provided under such conditions can be sufficient to maintain turgor in salinized seedlings. Compartmental analysis of Pro and beta-alanine betaine in leaf tissues demonstrated that these solutes, mainly located in vacuoles under nonsaline conditions, could be partly directed to the cytosol in response to salinization. Thus they did not conform with the predictions of the compatible solute hypothesis.

155 citations

Journal ArticleDOI
TL;DR: Internal transcribed spacer sequences of nuclear ribosomal DNA from 44 taxa of the genus Lupinus and five outgroup taxa were used for phylogenetic analysis, revealing an unexpectedly close relationship between the diverse sections Angustifoli and Lutei.
Abstract: ¨Internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA from 44 taxa of the genus Lupinus and five outgroup taxa were used for phylogenetic analysis. Lupinus appears as a strongly supported monophyletic genus, which is unambiguously part of the Genisteae. The lupines are distributed into five main clades in general accordance with their geographical origin. In the Old World, almost all the recognized taxonomic units are well resolved. The ITS data reveal an unexpectedly close relationship between the diverse sections Angustifoli and Lutei. The ITS results suggest a geographical division between the western New World lupines and the eastern ones. They also indicate the presence of some moderately to strongly supported groups of taxa, such as the Microcarpi‐Pusilli group, the L. spariflorus‐L. arizonicusgroup, the L. mexicanus‐ L. elegans group in the western New World, and the notable L. multiflorus‐L. paraguariensisgroup in the eastern New World. The latter group strongly suggests that the eastern South American compound- and simple-leaved perennial lupines derive from a common ancestor. However, apart from some exceptions, relationships within the genus still remain largely unresolved based on ITS data. The lack of resolution at the base of the genus is suggestive of a rapid initial radiation of the lupines subsequent to the dispersal of their common ancestor. Relative rate tests demonstrate the presence of rate heterogeneity of ITS sequences within Lupinus. In many pairwise comparisons between taxa, substitution rate inequalities are correlated with the habit (annual, perennial), suggesting some role for the generation time effects in the evolutionary history of lupines. Lupinus L. (Fabaceae) is a large and diverse genus comprising 200‐500 (Dunn and Gillett, 1966) annual and perennial herbaceous species, as well as a few soft-woody shrubs and small trees (Dunn, 1984; Turner, 1995), which occur in a wide range of ecogeographical conditions in both the New and the Old World. Lupines are more diverse in the New World with over 90% of the species in 1

152 citations

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TL;DR: Molecular phylogenetic analysis of the genus Spartina has been undertaken in order to understand phylogenetic relationships and genetic divergence among these hybridizing species, and results agree with hybridization patterns occurring in Spartina.

125 citations

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TL;DR: It becomes clear that salt tolerance in halophytic plants which might partly result from the cooperativity of a number of well-conserved mechanisms could also result from specific processes that could be modulated by the saline environment.

102 citations


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TL;DR: The compartmentalization of proline biosynthesis, accumulation and degradation in the cytosol, chloroplast and mitochondria is discussed and the role of prolines in cellular homeostasis, including redox balance and energy status, is described.

3,102 citations

Journal ArticleDOI
TL;DR: Halophytes, plants that survive to reproduce in environments where the salt concentration is around 200 mm NaCl or more, constitute about 1% of the world's flora and research should be concentrated on a number of 'model' species that are representative of the various mechanisms that might be involved in tolerance.
Abstract: Halophytes, plants that survive to reproduce in environments where the salt concentration is around 200 mM NaCl or more, constitute about 1% of the worlds flora. Some halophytes show optimal growth in saline conditions; others grow optimally in the absence of salt. However, the tolerance of all halophytes to salinity relies on controlled uptake and compartmentalization of Na+, K+ and Cl- and the synthesis of organic compatible solutes, even where salt glands are operative. Although there is evidence that different species may utilize different transporters in their accumulation of Na+, in general little is known of the proteins and regulatory networks involved. Consequently, it is not yet possible to assign molecular mechanisms to apparent differences in rates of Na+ and Cl- uptake, in root-to-shoot transport (xylem loading and retrieval), or in net selectivity for K+ over Na+. At the cellular level, H+-ATPases in the plasma membrane and tonoplast, as well as the tonoplast H+-PPiase, provide the transmembrane proton motive force used by various secondary transporters. The widespread occurrence, taxonomically, of halophytes and the general paucity of information on the molecular regulation of tolerance mechanisms persuade us that research should be concentrated on a number of model species that are representative of the various mechanisms that might be involved in tolerance.

2,127 citations

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TL;DR: Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species within normal ranges, thus preventing oxidative burst in plants.
Abstract: When exposed to stressful conditions, plants accumulate an array of metabolites, particularly amino acids. Amino acids have traditionally been considered as precursors to and constituents of proteins, and play an important role in plant metabolism and development. A large body of data suggests a positive correlation between proline accumulation and plant stress. Proline, an amino acid, plays a highly beneficial role in plants exposed to various stress conditions. Besides acting as an excellent osmolyte, proline plays three major roles during stress, i.e., as a metal chelator, an antioxidative defense molecule and a signaling molecule. Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species (ROS) within normal ranges, thus preventing oxidative burst ...

1,777 citations

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TL;DR: Information about metabolic regulation in response to drought, extreme temperature, and salinity stress is summarized and the signalling events involved in mediating stress-induced metabolic changes are presented.
Abstract: Plants regularly face adverse growth conditions, such as drought, salinity, chilling, freezing, and high temperatures. These stresses can delay growth and development, reduce productivity, and, in extreme cases, cause plant death. Plant stress responses are dynamic and involve complex cross-talk between different regulatory levels, including adjustment of metabolism and gene expression for physiological and morphological adaptation. In this review, information about metabolic regulation in response to drought, extreme temperature, and salinity stress is summarized and the signalling events involved in mediating stress-induced metabolic changes are presented.

1,683 citations

Journal Article

1,633 citations