2012 Research highlights

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As dispersal plays a key role in gene flow among populations, its evolutionary dynamics under environmental changes is particularly important. The inter-dependency of dispersal with other life history traits may constrain dispersal evolution, and lead to the indirect selection of other traits as a by-product of this inter-dependency.
Scientists from LIPM (INRA-CNRS) in collaboration with Génoscope (CEA-Institut de Génomique), as part of an international consortium *, have reported the genome sequence of a legume, Medicago truncatula (Mt) also known as Barrel Medic. This sequence provides easy access to the location of genes of interest in crop legumes (pea, field bean, lentil, alfalfa, clover) which will greatly facilitate breeding. Legumes have the capacity to fix atmospheric nitrogen; as a result legume crops do not require nitrogen fertilizers, which represents a real asset for a sustainable and more environmentally friendly agriculture. Results are published in Nature on November 17th 2011.
carp = invasive species
The world is currently undergoing an unprecedented decline in biodiversity, which is mainly attributable to human activities. For instance, nonnative species introduction, combined with the extirpation of native species, affects biodiversity patterns, notably by increasing the similarity among species assemblages. This biodiversity change, called taxonomic homogenization, has rarely been assessed at the world scale.
colored flies
Current evolutionary approaches reduce heredity to the sole genes. However, evidence is accruing that various forms of non-genetic information are transmitted across generations and thus participate to evolution. In a paper published in Nature Reviews Genetics, an international team encompassing three members of the federation de Recherche 3450 (EDB, UMR 5174 CNRS-Université Paul Sabatier-ENFA and “SEEM, USR 2936 CNRS) call for a more inclusive paradigm integrating all forms of non-genetic heredity into a single theory of evolution. It is the party taken by the TULIP Labex project to which three of the authors take part.
Poils racinaires
Legume plants are able to form a root endosymbiosis with some soil bacteria collectively called rhizobia. This interaction between legumes and rhizobia is highly specific and depends on the recognition by the plant of molecules produced by the rhizobia, called Nod Factors (NF). Hence, precise NF structures are required depending on the host plant. These data provide new information about NFP structure and on the mechanisms of NF recognition in the different steps of symbiosis in M. truncatula.
While reinforcement may play a role in all major modes of speciation, relatively little is known about the timescale over which species hybridize without evolving complete reproductive isolation. Birds have high potential for hybridization, and islands provide simple settings for uncovering speciation and hybridization patterns. Here we develop a phylogenetic hypothesis for a phenotypically diverse radiation of finch-like weaver-birds (Foudia) endemic to the western Indian Ocean islands.
Epidermal infection
Legumes and soil bacteria called rhizobia have co-evolved a facultative nitrogen-fixing symbiosis. Establishment of the symbiosis requires bacterial entry via root hair infection threads (ITs) and, in parallel, organogenesis of nodules that are subsequently invaded by bacteria. Tight control of nodulation and infection is required to maintain the mutualistic character of the interaction. Available evidence supports a passive bacterial role in nodulation and infection, after the microsymbiont has triggered the symbiotic plant developmental program.
Many stimuli such as hormones and elicitors induce changes in intracellular calcium levels to integrate information and activate appropriate responses. The Ca2+ signals are perceived by different Ca2+ sensors and calmodulin (CaM) is one of the best characterized in eukaryotes. Calmodulin-like (CML) proteins extend the Ca2+-toolkit in plants; they share sequence similarity with the ubiquitous and highly conserved CaM but their roles at physiological and molecular levels are largely unknown.
Bacterial typeIII effectors are recognized by plant intracellular nucleotide binding–leucine-rich repeat (NB-LRR) receptors. So far, processes linking activation of these receptors to downstream defense responses remain elusive.
During the initial stages of root colonization by either nitrogen-fixing rhizobia or arbuscular mycorrhizal (AM) fungi, the microsymbionts traverse outer root tissues within specialized intracellular compartments of plant origin, thus avoiding direct contact with the host cytoplasm and the activation of defence responses. In order to study the mechanisms underlying this unique form of transcellular infection we have developed in vivo experimental approaches based on confocal microscopy for the model legume Medicago truncatula with the objective of monitoring host cellular dynamics and associated intracellular signaling.
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Modification date: 07 June 2023 | Publication date: 10 December 2014 | By: G Esteve