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Javrezac, France

Rienth M.,Fondation Jean Poupelain | Rienth M.,Montpellier SupAgro | Romieu C.,French National Institute for Agricultural Research | Gregan R.,Trinity College Dublin | And 3 more authors.
Journal of Agricultural and Food Chemistry

A rapid and sensitive method is presented for the determination of proline in grape berries. Following acidification with formic acid, proline is derivatized by heating at 100 °C for 15 min with 3% ninhydrin in dimethyl sulfoxide, and the absorbance, which is stable for at least 60 min, is read at 520 nm. The method was statistically validated in the concentration range from 2.5 to 15 mg/L, giving a repeatability and intermediate precision of generally <3%; linearity was determined using the lack of fit test. Results obtained with this method concurred (r = 0.99) with those obtained for the same samples on an amino acid analyzer. In terms of sample preparation, a simple dilution (5-20-fold) is required, and sugars, primary amino acids, and anthocyanins were demonstrated not to interfere, as the latter are bleached by ninhydrin under the experimental conditions. The method was applied to the study of proline accumulation in the fruits of microvines grown in phytotrons, and it was established that proline accumulation and concentrations closely resemble those of field-grown macrovines. © 2014 American Chemical Society. Source

Rienth M.,Fondation Jean Poupelain | Rienth M.,Montpellier SupAgro | Torregrosa L.,Montpellier SupAgro | Luchaire N.,Montpellier SupAgro | And 5 more authors.
BMC Plant Biology

Background: Global climate change will noticeably affect plant vegetative and reproductive development. The recent increase in temperatures has already impacted yields and composition of berries in many grapevine-growing regions. Physiological processes underlying temperature response and tolerance of the grapevine fruit have not been extensively investigated. To date, all studies investigating the molecular regulation of fleshly fruit response to abiotic stress were only conducted during the day, overlooking possible critical night-specific variations. The present study explores the night and day transcriptomic response of grapevine fruit to heat stress at several developmental stages. Short heat stresses (2 h) were applied at day and night to vines bearing clusters sequentially ordered according to the developmental stages along their vertical axes. The recently proposed microvine model (DRCF-Dwarf Rapid Cycling and Continuous Flowering) was grown in climatic chambers in order to circumvent common constraints and biases inevitable in field experiments with perennial macrovines. Post-véraison berry heterogeneity within clusters was avoided by constituting homogenous batches following organic acids and sugars measurements of individual berries. A whole genome transcriptomic approach was subsequently conducted using NimbleGen 090818 Vitis 12X (30 K) microarrays.Results: Present work reveals significant differences in heat stress responsive pathways according to day or night treatment, in particular regarding genes associated with acidity and phenylpropanoid metabolism. Precise distinction of ripening stages led to stage-specific detection of malic acid and anthocyanin-related transcripts modulated by heat stress. Important changes in cell wall modification related processes as well as indications for heat-induced delay of ripening and sugar accumulation were observed at véraison, an effect that was reversed at later stages.Conclusions: This first day - night study on heat stress adaption of the grapevine berry shows that the transcriptome of fleshy fruits is differentially affected by abiotic stress at night. The present results emphasize the necessity of including different developmental stages and especially several daytime points in transcriptomic studies. © 2014 Rienth et al.; licensee BioMed Central Ltd. Source

Rienth M.,Fondation Jean Poupelain | Rienth M.,French National Institute for Agricultural Research | Torregrosa L.,French National Institute for Agricultural Research | Ardisson M.,French National Institute for Agricultural Research | And 2 more authors.
Australian Journal of Grape and Wine Research

Background and Aims: New high-throughput tools for transcriptomic analysis such as RNA sequencing have been developed rapidly in recent years. These technologies provide new opportunities for biologists to improve the understanding of gene expression underlying important physiological processes. The sequencing of RNA by next-generation technologies is, in particular, dependent on the use of pure and un-degraded RNA. Many fruits from perennial crops share an elevated concentration of tannins and polysaccharides and a strong dilution of cytosolic content upon vacuole hypertrophy. The grapevine berry presents these characteristics together with high vacuole acidity, which has never been taken into account in previous protocols, and poses thereby a particular challenge for RNA extraction. Methods and Results: In order to counterbalance these limitations, we developed a new extraction protocol based on a tri-sodium-citrate extraction buffer that has a high buffer capacity and proved to be particularly suitable for low pH plant tissue. Conclusions: The proposed RNA extraction procedure produces consistently high-quality RNA (RNA integrity number>8 up to 10; 260nm/280nm>2; 260nm/230nm>1.9) with an elevated yield [20μg/g fresh mass (FM) for ripe berries up to 150μg/FM for green berries]. The method was developed initially for berry tissues but proved also to be efficient for other grapevine tissues, such as nodes, roots, leaves, seeds, lignified shoots and flowers. Significance of the Study: The method is most suitable for modern gene expression analysis methods, such as RNA sequencing and microarray studies. Successful construction of cDNA libraries and high numbers of detected reads obtained by next-generation RNA sequencing underline the applicability of the protocol. © 2014 Australian Society of Viticulture and Oenology Inc. Source

De Royer Dupre N.,Fondation Jean Poupelain | De Royer Dupre N.,Montpellier SupAgro | Schneider R.,UMT QUALINNOV IFV Pech ROUGE | Payan J.C.,Ifv Institute Francais Of La Vigne Et Du Vin | And 2 more authors.
Journal of Agricultural and Food Chemistry

We studied the effect of vine water status on the dimethyl sulfur potential (DMSP), ammonium, and amino acid contents of the berry during the maturation of Grenache Noir grapes. Water deficit increased the accumulation of amino acids in berries and favored yeast assimilable amino nitrogen. Similarly, ammonium content was higher in berries from vines subjected to moderate water deficit. DMSP content followed the same trend as yeast assimilable amino acid content, with higher concentrations observed in the berries of vines subjected to water deficit. The high DMSP and yeast assimilable nitrogen contents of musts from vines subjected to water deficit resulted in a better preservation of DMSP during winemaking. The wines produced from these musts had a higher DMSP level and would therefore probably have a higher aroma shelf life, because the DMSP determines the rate of release of dimethyl sulfur during wine storage, and this compound enhances fruity notes. © 2014 American Chemical Society. Source

Rienth M.,Fondation Jean Poupelain | Rienth M.,Montpellier SupAgro | Dauzat M.,Montpellier SupAgro | Pellegrino A.,Montpellier SupAgro | And 3 more authors.
Vitis - Journal of Grapevine Research

In order to reduce energy waste for artificial lights and subsequent air conditioning in plant growth chambers, the aim of this preliminary study was to evaluate the feasibility of growing the microvine under 100% of LED illumination. Plant growth under two different LED lights was compared amongst each other and with plants maintained in greenhouse conditions. Regarding the impact on the reproductive and vegetative systems, the study showed that LED light is suitable to grow microvines in confined environments. Plants exposed to LED light exhibited similar leaf emergence rate but reduced vegetative and reproductive organ size compared to plants grown in the greenhouse. Photosynthesis for plants exposed to LED light was higher than what is usually observed on grapevine under natural conditions. Source

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