An improved method to measure spatial variation in root respiration: application to the taproot of a young peach tree Prunus persica

This paper presents an improved method to measure the local root respiration, by suspending them in a gel which could be sampled using an oxygen microelectrode. The effect of gel type on the oxygen diffusion and on transport of oxygen from the shoot to the root was studied. The local root respiration rates were estimated by fitting models for oxygen diffusion and consumption to the measured oxygen profile data obtained with the microelectrodes. The best fits to our experimental data were obtained with a model which describes oxygen radial diffusion, root consumption, and microbial consumption that declines with distance from the root. We applied this method along the taproot of Prunus persica (L.) Batsch. Local respiration level was consistent with root system respiration rate estimated in other plants of similar age and dimension, as measured by conventional gas chromatography. In accordance with published results, which have only been reported on primary structure respiration, the specific respiration rate was at a maximum in the elongating apical zone; it then decreased with distance from the root tip up to the root hair zone, where it increased.Une méthode améliorée de mesure de la respiration racinaire : application au pivot d'un jeune pêcher, Prunus persica. Cet article propose une méthode de mesure locale de la respiration adaptée aux racinaires. Les racines sont incluses dans un gel d'agar permettant une mesure du gradient de concentration en oxygène à leur surface à l'aide d'une microélectrode. L'influence de la concentration du gel sur la diffusion de l'oxygène et l'influence des transferts longitudinaux à l'intérieur des racines sont analysées. L'intensité respiratoire locale est déduite de l'ajustement d'un modèle de diffusion et de consommation au profil de concentration en oxygène mesuré par la microélectrode. Les meilleurs ajustements sont obtenus quand le modèle décrit la diffusion dans le gel, la respiration racinaire, et une respiration microbienne autour des racines qui décline en s'en éloignant. Cette méthode a été utilisée pour mesurer l'intensité respiratoire de l'ensemble d'un pivot de Prunus persica (L.) Batsch. Les valeurs d'intensité respiratoire mesurée selon cette méthode locale sont en accord avec celles établies par chromatographie gazeuse pour l'ensemble de systèmes racinaires similaires. En accord avec les résultats publiés qui se limitaient à la zone en structure primaire, l'intensité respiratoire a présenté un maximum dans la zone apicale en croissance, suivi d'un minimum, avant un retour à une valeur élevée dans la zone pilifère

PROSPECT-4 and 5: Advances in the leaf optical properties model separating photosynthetic pigments

The PROSPECT leaf optical model has, to date, combined the effects of photosynthetic pigments, but a finer discrimination among the key pigments is important for physiological and ecological applications of remote sensing. Here we present a new calibration and validation of PROSPECT that separates plant pigment contributions to the visible spectrum using several comprehensive datasets containing hundreds of leaves collected in a wide range of ecosystem types. These data include leaf biochemical (chlorophyll a, chlorophyll b, carotenoids, water, and dry matter) and optical properties (directional-hemi spherical reflectance and transmittance measured from 400 nm to 2450 nm). We first provide distinct in vivo specific absorption coefficients for each biochemical constituent and determine an average refractive index of the leaf interior. Then we invert the model on independent datasets to check the prediction of the biochemical content of intact leaves. The main result of this study is that the new chlorophyll and carotenoid specific absorption coefficients agree well with available in vitro absorption spectra, and that the new refractive index displays interesting spectral features in the visible, in accordance with physical principles. Moreover, we improve the chlorophyll estimation (RMSE=9 mu g/cm(2)) and obtain very encouraging results with carotenoids (RMSE=3 mu g/cm(2)). Reconstruction of reflectance and transmittance in the 400-2450 nm wavelength domain using PROSPECT is also excellent, with small errors and low to negligible biases. Improvements are particularly noticeable for leaves with low pigment conten

Interactions between trans-resveratrol and CpLIP2 lipase/acyltransferase: Evidenced by fluorescence and in silico

International audienc

Increase in insulin sensitivity by the association of chicoric acid and chlorogenic acid contained in a natural chicoric acid extract (NCRAE) of chicory ( Cichorium intybus L.) for an antidiabetic effect

UMR AGAP équipe DAAVInternational audienceChicory (Cichorium intybus L.) is an indigenous vegetable widely cultivated in Europe, America and Asia. In ancient times, the leaves, flowers, seeds, and roots have been used as a wealth of health benefits including its tonic effects, the ability to ease digestive problems and to detoxify liver. In Indian traditional therapy, chicory was known to possess antidiabetic effect. In the traditional medicine of Bulgaria and Italy, chicory was used as hypoglycemic decoctions

Water shortage and quality of fleshy fruits--making the most of the unavoidable

International audienceExtreme climatic events, including drought, are predicted to increase in intensity, frequency, and geographic extent as a consequence of global climate change. In general, to grow crops successfully in the future, growers will need to adapt to less available water and to take better advantage of the positive effects of drought. Fortunately, there are positive effects associated with drought. Drought stimulates the secondary metabolism, thereby potentially increasing plant defences and the concentrations of compounds involved in plant quality, particularly taste and health benefits. The role of drought on the production of secondary metabolites is of paramount importance for fruit crops. However, to manage crops effectively under conditions of limited water supply, for example by applying deficit irrigation, growers must consider not only the impact of drought on productivity but also on how plants manage the primary and secondary metabolisms. This question is obviously complex because during water deficit, trade-offs among productivity, defence, and quality depend upon the intensity, duration, and repetition of events of water deficit. The stage of plant development during the period of water deficit is also crucial, as are the effects of other stressors. In addition, growers must rely on relevant indicators of water status, i.e. parameters involved in the relevant metabolic processes, including those affecting quality. Although many reports on the effects of drought on plant function and crop productivity have been published, these issues have not been reviewed thus far. Here, we provide an up-to-date review of current knowledge of the effects of different forms of drought on fruit quality relative to the primary and secondary metabolisms and their interactions. We also review conventional and less conventional indicators of water status that could be used for monitoring purposes, such as volatile compounds. We focus on fruit crops owing to the importance of secondary metabolism in fruit quality and the importance of fruits in the human diet. The issue of defence is also briefly discussed