Daniel Laffray
University of Paris
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Environmental and Experimental Botany | 2000
Marcel G Costa França; Anh Thu Pham Thi; Carlos Pimentel; Roberto Oscar Pereyra Rossiello; Yasmine Zuily-Fodil; Daniel Laffray
Relatively little ecophysiological research has been conducted to determine the responses to drought of Phaseolus vulgaris. Four bean cultivars (cvs.) from Brazil, A320, Carioca, Ouro Negro and Xodó were submitted to an imposed water deficit in order to evaluate the importance of some adaptive mechanisms of drought resistance through the analysis of growth parameters, water status, gas exchange and indicators of tolerance mechanisms at the cellular level. During the drought treatment, relative growth rates were more reduced for A320 and Xodó than Carioca and Ouro Negro. A320 closed its stomata very rapidly and complete stomatal closure was obtained at Psi(w)=-0.6 MPa, in contrast to the other cvs. where stomata were fully closed only at Psi(w)=-0.9 MPa. Net assimilation rates were closely related to stomatal conductances. Mechanisms at the cellular level appeared to be mostly important for higher tolerance. Carioca and Ouro Negro, when compared to A320 and Xodó, were characterized by having better drought tolerance mechanisms and higher tissue water retention capacity leading to a better growth under water deficits. The leaf dehydration rates of those cvs. were slow whereas those of the drought sensitive cvs. were rapid. The results were confirmed by the electrolyte leakage test and leaf osmotic potential measurements, which indicated higher membrane resistance and osmotic adjustment in the two tolerant cvs. Carioca and Ouro Negro. It appears from this study that despite being cultivated in the same geographical region, the four cvs. of P. vulgaris displayed somewhat different drought adaptive capacities for prolonged drought during the vegetative phase.
Environmental and Experimental Botany | 1998
Maria H. Cruz de Carvalho; Daniel Laffray; Philippe Louguet
Three cultivars differing in their susceptibility to water stress were compared—Phaseolus vulgaris cv. Carioca (susceptible), Vigna unguiculata cv. IT83D (intermediately tolerant) and V. unguiculata cv. EPACE-1 (tolerant)—during an imposed water stress treatment. Variation in leaf gas exchange (i.e. assimilation and stomatal conductance) and leaf relative water content in response to progressive substrate water depletion were investigated. To verify the extent of the injury caused by the drought treatment, leaf gas exchange was measured after rehydration. In the three cultivars, stomatal conductance declined before leaf relative water content was affected. P. vulgaris showed the largest decrease in the rate of stomatal conductance with decreasing substrate water content compared to both V. unguiculata cultivars. Photosynthetic assimilation rates were largely dependent on stomatal aperture, but there was evidence of the participation of non-stomatal factors in the reduction of CO2 fixation. The response of leaf gas exchange parameters to severe water stress conditions differed significantly between P. vulgaris and V. unguiculata cultivars. After rehydration, cultivars can be characterised according to the degree of injury induced by the drought treatment: V. unguiculata cv. EPACE-1 as the least affected, V. unguiculata cv. IT83D slightly affected and P. vulgaris cv. Carioca strongly affected. Similar ranking was obtained with experiments previously performed at a cellular and subcellular level. Our results confirm the utility of physiological parameters as early screening tools for drought resistance in bean cultivars.
Physiologia Plantarum | 2008
Ana Rita Matos; Agnès Gigon; Daniel Laffray; Stéphane Petres; Yasmine Zuily-Fodil; Anh-Thu Pham-Thi
Patatin-like genes have recently been cloned from several plant species and found to be involved in stress responses and development. In previous work, we have shown that a patatin-like gene encoding a galactolipid acyl hydrolase (EC 3.1.1.26) was stimulated by drought in the leaves of the tropical legume, Vigna unguiculata L. Walp. The aim of the present work was to study the expression of patatin-like genes in Arabidopsis thaliana under water deficit. Expression of six genes was studied by reverse transcriptase polymerase chain reaction in leaves of plants submitted to progressive drought stress induced by withholding water and also in different plant organs. Three genes, designated AtPAT IIA, AtPAT IVC and AtPAT IIIA, were shown to be upregulated by water deficit but with different kinetics, while the other patatin-like genes were either constitutive or not expressed in leaves. The accumulation of transcripts of AtPAT IIA in the early stages of the drought treatment was coordinated with the upregulation of lipoxygenase and allene oxide synthase genes. AtPAT IIA expression was also induced by wounding and methyl jasmonate treatments. The in vitro lipolytic activity toward monogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylcholine and phosphatidylglycerol was confirmed by producing the recombinant protein ATPAT IIA in insect cells. The analysis of free fatty acid pools in drought-stressed leaves shows an increase in the relative amounts of trans-3-hexadecenoic acid at the beginning of the treatment followed by a progressive accumulation of linoleic and linolenic acids. The possible roles of AtPAT IIA in lipid signaling and membrane degradation under water deficit are discussed.
Journal of Environmental Management | 2012
Ulrike Jana; Vincent Chassany; Georges Bertrand; Maryse Castrec-Rouelle; Emmanuel Aubry; Simon Boudsocq; Daniel Laffray; Anne Repellin
One of the objectives of this study was to assess the contamination levels in the tailings of an old antimony mine site located in Ouche (Cantal, France). Throughout the 1.3 ha site, homogenous concentrations of antimony and arsenic, a by-product of the operation, were found along 0-0.5 m-deep profiles. Maximum concentrations for antimony and arsenic were 5780 mg kg(-1) dry tailings and 852 mg kg(-1) dry tailings, respectively. Despite the presence of the contaminants and the low pH and organic matter contents of the tailings, several patches of vegetation were found. Botanical identification determined 12 different genera/species. The largest and most abundant plants were adult pines (Pinus sylvestris), birches (Betula pendula) and the bulrush (Juncus effusus). The distribution of the metalloids within specimens of each genera/species was analysed in order to deduce their concentration and translocation capacities. This was the second goal of this work. All plant specimens were highly contaminated with both metalloids. Most were root accumulators with root to shoot translocation factors <1. Whereas contamination levels were high overall, species with both a low translocation factor and a low root accumulation coefficient were identified as suitable candidates for the complete revegetation of the site. Species combining those characteristics were the perennials P. sylvestris, B. pendula, Cytisus scoparius and the herbaceous Plantago major, and Deschampsia flexuosa.
Bulletin de la Société Botanique de France. Actualités Botaniques | 1990
Daniel Laffray; Philippe Louguet
SummaryDuring drought, stomata allow the regulation of CO2 and water vapor exchanges of the plant. The relationships between stomatal conductance and leaf water potential and the stomatal responses to air water vapor deficit are studied and their mechanisms analysed. The partial control of photosynthesis by stomata is reexamined taking into account the new results showing a stomatal aperture patchiness on the leaf during drought. In a last part, interest and limitations of the use of stomatal responses in plant breeding for more drought resistant cultivars are discussed in relation to the overall mechanisms of drought resistance in the plant kingdom.
Annals of Botany | 2004
Agnès Gigon; Ana-Rita Matos; Daniel Laffray; Yasmine Zuily-Fodil; Anh-Thu Pham-Thi
Ecology Letters | 2005
Manuel Blouin; Yasmine Zuily-Fodil; Anh-Thu Pham-Thi; Daniel Laffray; Georges Reversat; Anne Pando; Jérôme Ebagnerin Tondoh; Patrick Lavelle
Environmental and Experimental Botany | 2005
Danièle Clavel; Nani Khady Drame; Harold Roy-Macauley; Serge Braconnier; Daniel Laffray
Physiologia Plantarum | 1999
C. Pimentel; Daniel Laffray; P. Louguet
Soil Biology & Biochemistry | 2010
Ulrike Jana; Sébastien Barot; Manuel Blouin; Patrick Lavelle; Daniel Laffray; Anne Repellin