Publications (4)25.44 Total impact
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Article: Natural variation of Arabidopsis response to nitrogen availability.
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ABSTRACT: Our understanding of plant growth in response to nitrogen (N) supply is mainly based on studies of mutants and transformants. This study explored the natural variability of Arabidopsis thaliana first to find out its global response to N availability and secondly to characterize the plasticity for growth and N metabolism among 23 genetically distant accessions under normal (N+), limited (N-), and starved (N0) N supplies. Plant growth was estimated by eight morphological traits characterizing shoot and root growth and 10 metabolic parameters that represented N and carbon metabolism. Most of the studied traits showed a large variation linked to genotype and nutrition. Furthermore, Arabidopsis growth was coordinated by master traits such as the shoot to root ratio of nitrate content in N+, root fresh matter and root amino acids in N-, and shoot fresh matter together with root thickness in N0. The 23 accessions could be gathered into four different groups, according to their growth in N+, N-, and N0. Phenotypic profiling characterized four different adaptative responses to N- and N0. Class 1 tolerated N limitation with the smallest decrease in shoot and root biomass compared with N+, while class 2 presented the highest resistance to N starvation by preferential increased root growth, huge starch accumulation, and high shoot nitrate content. In contrast, class 3 plants could tolerate neither N limitation nor N starvation. Small plants of class 4 were different, with shoot biomass barely affected in N- and root biomass unaffected in N0.Journal of Experimental Botany 09/2011; 63(1):91-105. · 5.36 Impact Factor -
Article: The Arabidopsis TOR kinase links plant growth, yield, stress resistance and mRNA translation.
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ABSTRACT: Plants, unlike animals, have plastic organ growth that is largely dependent on environmental information. However, so far, little is known about how this information is perceived and transduced into coherent growth and developmental decisions. Here, we report that the growth of Arabidopsis is positively correlated with the level of expression of the TARGET OF RAPAMYCIN (TOR) kinase. Diminished or augmented expression of the AtTOR gene results in a dose-dependent decrease or increase, respectively, in organ and cell size, seed production and resistance to osmotic stress. Strong downregulation of AtTOR expression by inducible RNA interference also leads to a post-germinative halt in growth and development, which phenocopies the action of the plant hormone abscisic acid, to an early senescence and to a reduction in the amount of translated messenger RNA. Thus, we propose that the AtTOR kinase is one of the contributors to the link between environmental cues and growth processes in plants.EMBO Reports 10/2007; 8(9):864-70. · 7.36 Impact Factor -
Article: The Arabidopsis TOR kinase links plant growth, yield, stress resistance and mRNA translation
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ABSTRACT: Plants, unlike animals, have plastic organ growth that is largely dependent on environmental information. However, so far, little is known about how this information is perceived and transduced into coherent growth and developmental decisions. Here, we report that the growth ofEMBO Reports 08/2007; 8(9):864-870. · 7.36 Impact Factor -
Article: Systematic silencing of a tobacco nitrate reductase transgene in lettuce (Lactuca sativa L.).
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ABSTRACT: A population of 50 independent transgenic lettuces transformed with a nitrate reductase coding sequence under the control of the 35S promoter was studied. None of them showed significantly lower nitrate levels when compared with the untransformed plants, despite the presence of nitrate reductase (NR) activity that derives from the transgene in at least four of the transformants. No repercussion on total NR activity (endogenous+transgenic) was detected in these plants. Nevertheless, 28% of the transformants showed phenotypes characteristic of a general silencing of the NR genes as already described in tobacco and potato, i.e. bleaching of the leaves leading to the death of the plant. By northern blots, it was shown that the transgene was silenced in these chlorotic plants and also in the plants that did not show symptoms of chlorosis. Thus a silencing process specifically directed against the NR mRNA derived from the transgene occurred very early in the development of all the plants studied, whatever homologous endogenous NR mRNA is present in the plant. In some cases this transgene-specific silencing was shown subsequently to extend to the homologous endogenous NR mRNA. These results suggest that, in lettuce, the level of nitrate reductase mRNA is under tight expression control and this is able specifically to target transgenic transcripts by a post-transcriptional gene silencing (PTGS) mechanism during the first stage of development of the plantlet.Journal of Experimental Botany 10/2005; 56(419):2379-88. · 5.36 Impact Factor
