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Remy J.-J.,French National Institute for Agricultural Research
Current Biology | Year: 2010

Sensory imprinting produces life-long attachment to environmental features experienced during a critical period of early development. Imprinting of this kind is highly conserved in evolution and is an important form of adaptive behavioral plasticity [1]. The nematode Caenorhabditis elegans undergoes such adaptation to new environments through imprinting: attractive odorants, when present during the first larval stage, produce life-long olfactory imprints that enhance attraction and egg-laying rates in the adults [2]. Here I report evidence that the olfactory imprint can be transmitted to the next generation. If the imprint is generated successively over more than four generations, it is not just transmitted through one further generation, but rather, it is stably inherited through many following generations. While the transient nature of the inheritance suggests the existence of resetting mechanisms, stable trans-generational inheritance of the kind reported here raises the possibility that a behavioral alteration produced by an environmental change might be genetically assimilated after a limited number of generations. © 2010 Elsevier Ltd. All rights reserved. Source


Tardieu F.,French National Institute for Agricultural Research
Journal of Experimental Botany | Year: 2012

Most traits associated with drought tolerance have a dual effect, positive in very severe scenarios and negative in milder scenarios, or the opposite trend. Their effects also depend on other climatic conditions such as evaporative demand or light, and on management practices. This is the case for processes associated with cell protection and with avoidance, but also for the maintenance of growth or photosynthesis, high water use efficiency, large root systems or reduced abortion rate under water deficit. Therefore, spectacular results obtained in one drought scenario may have a limited interest for improving food security in other geographical areas with water scarcity. The most relevant questions on drought tolerance are probably, 'Does a given allele confer a positive effect on yield in an appreciable proportion of years/scenarios in a given area or target population of environment (TPE)?'; 'In a given site or TPE, what is the trade-off between risk avoidance and maintained performance?'; and 'Will a given allele or trait have an increasingly positive effect with climate change?' Considerable progress has already occurred in drought tolerance. Nevertheless, explicitly associating traits for tolerance to drought scenarios may have profound consequences on the genetic strategies, with a necessary involvement of modelling. © 2011 The Author(s). Source


Lannou C.,French National Institute for Agricultural Research
Annual Review of Phytopathology | Year: 2012

The first section presents the quantitative traits of pathogenicity that are most commonly measured by plant pathologists, how the expression of those traits is influenced by environmental factors, and why the traits must be taken into account for understanding pathogen evolution in agricultural systems. Particular attention is given to the shared genetic control of these traits by the host and the pathogen. Next, the review discusses how quantitative traits account for epidemic development and how they can be related to pathogen fitness. The main constraints that luence the evolution of quantitative traits in pathogen populations are detailed. Finally, possible directions for research on the management of pathogen virulence (as defined by evolutionists) and host quantitative resistance are presented. The review evaluates how the theoretical corpus developed by epidemiologists and evolutionists may apply to plant pathogens in the context of agriculture. The review also analyzes theoretical papers and compares the modeling hypotheses to the biological characteristics of plant pathogens. © 2012 by Annual Reviews. All rights reserved. Source


Jacquemond M.,French National Institute for Agricultural Research
Advances in Virus Research | Year: 2012

Cucumber mosaic virus (CMV) is an important virus because of its agricultural impact in the Mediterranean Basin and worldwide, and also as a model for understanding plant-virus interactions. This review focuses on those areas where most progress has been made over the past decade in our understanding of CMV. Clearly, a deep understanding of the role of the recently described CMV 2b gene in suppression of host RNA silencing and viral virulence is the most important discovery. These findings have had an impact well beyond the virus itself, as the 2b gene is an important tool in the studies of eukaryotic gene regulation. Protein 2b was shown to be involved in most of the steps of the virus cycle and to interfere with several basal host defenses. Progress has also been made concerning the mechanisms of virus replication and movement. However, only a few host proteins that interact with viral proteins have been identified, making this an area of research where major efforts are still needed. Another area where major advances have been made is CMV population genetics, where contrasting results were obtained. On the one hand, CMV was shown to be prone to recombination and to show high genetic diversity based on sequence data of different isolates. On the other hand, populations did not exhibit high genetic variability either within plants, or even in a field and the nearby wild plants. The situation was partially clarified with the finding that severe bottlenecks occur during both virus movement within a plant and transmission between plants. Finally, novel studies were undertaken to elucidate mechanisms leading to selection in virus population, according to the host or its environment, opening a new research area in plant-virus coevolution. © 2012 Elsevier Inc. Source


Girard A.L.,French National Institute for Agricultural Research
The Plant cell | Year: 2012

The plant cuticle consists of cutin, a polyester of glycerol, hydroxyl, and epoxy fatty acids, covered and filled by waxes. While the biosynthesis of cutin building blocks is well documented, the mechanisms underlining their extracellular deposition remain unknown. Among the proteins extracted from dewaxed tomato (Solanum lycopersicum) peels, we identified GDSL1, a member of the GDSL esterase/acylhydrolase family of plant proteins. GDSL1 is strongly expressed in the epidermis of growing fruit. In GDSL1-silenced tomato lines, we observed a significant reduction in fruit cuticle thickness and a decrease in cutin monomer content proportional to the level of GDSL1 silencing. A significant decrease of wax load was observed only for cuticles of the severely silenced transgenic line. Fourier transform infrared (FTIR) analysis of isolated cutins revealed a reduction in cutin density in silenced lines. Indeed, FTIR-attenuated total reflectance spectroscopy and atomic force microscopy imaging showed that drastic GDSL1 silencing leads to a reduction in ester bond cross-links and to the appearance of nanopores in tomato cutins. Furthermore, immunolabeling experiments attested that GDSL1 is essentially entrapped in the cuticle proper and cuticle layer. These results suggest that GDSL1 is specifically involved in the extracellular deposition of the cutin polyester in the tomato fruit cuticle. Source

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