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Esca disease as well as Botryosphaeria and Eutypa dieback cause considerable economic problems for vineyards worldwide, and currently, no efficient treatment is available to control these diseases. For these three grapevine trunk diseases (GTDs), the main physiological effects reported concern carbohydrate metabolism and defence responses in the different organs of vine. In the trunk, a depletion of starch reserves in woody tissues is associated with fungal colonization; in the leaves, where pathogens are not present, the carbohydrate metabolism is also affected as revealed by a decline of the photosynthetic rate. A consequence of these disturbances is a lower pool of carbon reserves that might contribute to a decrease of plant development and vigour during the subsequent year. Other metabolic activities such as lipid and amino acid metabolism are down regulated. The perturbation of these primary metabolisms is often associated with the induction of defence responses. The development of biochemical barriers resulting from the accumulation of both tyloses and gummosis is observed during the infection of the wood causing blockage of the xylem vessels and thus limiting the fungal invasion. Their progression in the wood is also inhibited by the formation of polyphenol-rich reaction zones and by the accumulation of pathogenesis-related proteins, and the oxidative burst and the production of reactive oxygen species. Additionally, detoxification processes of the vine are involved; this reaction could be linked to the production of extracellular compounds by GTD agents some of which are phytotoxic. As a consequence, the sensory quality of berries and probably the wine made from these berries decrease. This review presents an overview of the physiological modifications described in vines affected by GTDs.

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Low temperatures damage many temperate crops, including grapevine, which, when exposed to chilling, can be affected by symptoms ranging from reduced yield up to complete infertility. We have previously demonstrated that Burkholderia phytofirmans PsJN, a plant growth-promoting rhizobacteria (PGPR) that colonizes grapevine, is able to reduce chilling-induced damage. We hypothesized that the induced tolerance may be explained at least partly by the impact of bacteria on grapevine photosynthesis or carbohydrate metabolism during cold acclimation. To investigate this hypothesis, we monitored herein the fluctuations of photosynthesis parameters (net photosynthesis [Pn], intercellular CO2 concentration, stomatal conductances, ΦPSII, and total chlorophyll concentration), starch, soluble sugars (glucose, fructose, saccharose, mannose, raffinose, and maltose), and their precursors during 5 days of chilling exposure (4°C) on grapevine plantlets. Bacterization affects photosynthesis in a non–stomatal dependent pattern and reduced long-term impact of chilling on Pn. Furthermore, all studied carbohydrates known to be involved in cold stress tolerance accumulate in non-chilled bacterized plantlets, although some of them remained more concentrated in the latter after chilling exposure. Overall, our results suggest that modification of carbohydrate metabolism in bacterized grapevine plantlets may be one of the major effects by which this PGPR reduces chilling-induced damage.

Plant infection by pathogens generates various forms of symptoms. Most of them have been described as soon as they become visible, whereas preceding, discrete signs during incubation are poorly or not understood. In Vitis vinifera, esca-related pathogenic fungi inhabit living trunk wood and induce the so-called apoplexy, a sudden wilting of leaves within a few days. To further understand the apoplexy expression, the period preceding symptom appearance was investigated by following physiological and molecular markers associated with photosynthetic mechanisms and stress responses. Within the week preceding symptoms, drastic physiological alterations of photosynthesis were registered in pre-apoplectic vines, as revealed by a decrease in gas exchange, changes in chlorophyll fluorescence, and repression of photosynthesis-related genes. In the meantime, expression of defense-related genes was induced and amplified during symptom expression. Water-stress-related genes were specifically investigated because water transport may be impeded by clogging xylem vessels due to esca-causing fungi. Neither of the tested water-stress-related genes was affected in pre-apoplectic grapevine leaves whereas these genes were downregulated in drying leaves. Our results suggest that, during incubation of esca apoplexy, grapevine perceives some signals (likely fungi-originated toxins) and reacts by reducing photosynthesis and triggering defense mechanisms.

Resume Les maladies du bois de la vigne sont tres dommageables pour la perennite du patrimoine viticole car les parasites responsables de ces maladies attaquent les organes perennes provoquant a plus ou moins long terme la mort du cep. L'esca et le BDA sont des acteurs majeurs de ces maladies de deperissement. Les symptomes s'expriment au niveau du bois par la formation de necroses sectorielles et/ou centrales, par la presence de bandes brunes ou de chancres et au niveau foliaire par des decolorations et des dessechements qui peuvent etre foudroyants. Dans cette revue nous etudierons pour les deux maladies la symptomatologie, les champignons associes et l'interaction hote-pathogene. Pour finir, un bilan concernant les methodes de lutte est evoque. Pour citer cet article : P. Larignon et al., C. R. Biologies 332 (2009).

In grapevine, stimulation of defence responses was evidenced in response to various types of abiotic stresses in both leaves and berries, as revealed by the increasing expression of genes encoding defence-related proteins or the stimulation of their corresponding activities. However, the capability of inflorescences to respond to abiotic stresses has never been investigated. Therefore, plant defence reactions in response to UV-C irradiation were followed in inflorescences and young clusters focusing on both bunchstems (peduncle and pedicels) and developing flowers/berries from separated floral buds stage [Biologische Bundesanstalt, Bundessortenamt and CHemical industry (BBCH) stage 57] to groat-sized berries stage (BBCH 73). For this purpose, the expression of various genes coding for pathogenesis-related (PR) proteins (class I and III chitinases, Chi1b and CH3; beta-1,3-glucanase, GLUC), an enzyme of the phenylpropanoid pathway (phenylalanine ammonia-lyase, PAL), and stilbene synthase (STS) was analysed in parallel with variations of chitinase activity and the accumulation of the phytoalexin resveratrol. Multiple defence responses were induced in bunchstems of both inflorescences and clusters following UV-C treatment. First, expression of genes encoding PR proteins was stimulated and chitinase activity was enhanced. Secondly, PAL and STS expression increased in association with resveratrol accumulation. Amazingly, none of the tested defence processes was induced in grapevine flowers following UV-C exposure, whatever the stage analysed. Similarly, in berries at fruit set, induction of gene expression was weak and neither an increase in chitinase activity nor resveratrol synthesis was noticed. However, in groat-sized berries, responsiveness to UV-C increased, as revealed by the induction of CH3, PAL, and STS expression, together with resveratrol accumulation. The differential responsiveness between bunchstems, flowers, and berries is discussed.

The effects of the two botryticides, fludioxonil (fdx) and fenhexamid (fhd), were investigated on grapevine leaves (Vitis vinifera L. cv. Pinot noir) following photosynthesis and defense mechanisms. Treatments were carried out in vineyard at the end of flowering. Phytotoxicity of both fungicides was evaluated by measuring variations of leaf photosynthetic parameters and correlated expression of photosynthesis-related genes. Results demonstrated that similar decrease in photosynthesis was caused by fdx and fhd applications. Moreover, the mechanism leading to photosynthesis alteration seems to be the same for both fungicides. Stomatal limitation to photosynthetic gas exchange did not change following treatments indicating that inhibition of photosynthesis was mostly attributed to non-stomatal factors. Nevertheless, fungicides-induced depression of photosynthesis was related neither to a decrease in Rubisco carboxylation efficiency and in the capacity for regeneration of ribulose 1,5-bisphosphate nor to loss in PSII activity. However, fdx and fhd treatments generated repression of genes encoding proteins involved in the photosynthetic process. Indeed, decreased photosynthesis was coupled with repression of PsbP subunit of photosystem II (psbP1), chlorophyll a/b binding protein of photosystem I (cab) and Rubisco small subunit (rbcS) genes. A repression of these genes may participate in the photosynthesis alteration. To our knowledge, this is the first study of photosynthesis-related gene expression following fungicide stress. In the meantime, defense responses were followed by measuring chitinase activity and expression of varied defense-related genes encoding proteins involved in phenylpropanoid synthesis (PAL) or octadecanoid synthesis (LOX), as well as pathogenesis-related protein (Chi4C). No induction of defense was observed in botryticides-treated leaves. To conclude, the photosynthesis is affected without any triggering of plant defense responses.

Sugars play an important role in grapevine flowering. This complex process from inflorescence initiation to fruit maturity takes two growing seasons. Currently, most of the available data concern the involvement of sugars as energy sources during the formation of reproductive structures from initiation of inflorescences during the summer of the first year, until flower opening during the following spring. Sugars devoted to the development of reproductive structures are supplied either by wood reserves or by photosynthesis in leaves or inflorescences, depending on the stage of development. Female meiosis appears to be a key point in the success of flower formation because (i) flowers are vulnerable at this stage and (ii) it corresponds in the whole plant to the transition between reserve mobilization from perennial organs (roots, trunk, and canes) towards efficient leaf photosynthesis. The perturbation of reserve replenishment during the previous year provokes perturbation in the development of inflorescences, whereas altering the photosynthetic sources affects the formation of flowers during the same year. In particular, a lack of sugar availability in flowers at female meiosis caused by various environmental or physiological fluctuations may lead to drastic flower abortion. Apart from energy, sugars also play roles as regulators of gene expression and as signal molecules that may be involved in stress responses. In the future, these two topics should be further investigated in the grapevine considering the sensitivity of flowers to environmental stresses at meiosis.

Liquid chromatography-diode array screening of the organic extract of the cultures of 13 isolates of the fungus Neofusicoccum parvum, the main causal agent of botryosphaeria dieback of grapevine, showed similar metabolites. One strain was selected for further chemical studies and led to the isolation and characterisation of 13 metabolites. Structures were elucidated through spectroscopic analyses, including one- and two-dimensional NMR and mass spectrometry, and through comparison to literature data. The isolated compounds belong to four different chemical families: five metabolites, namely, ( )-terremutin (1), (+)-terremutin hydrate (2), (+)-epi-sphaeropsidone (3) ( )-4-chloro-terremutin hydrate (4) and(+)-4- hydroxysuccinate-terremutin hydrate (5), belong to the family of dihydrotoluquinones; two metabolites, namely, (6S,7R) asperlin (6) and (6R,7S)-dia-asperlin (7), belong to the family of epoxylactones; four metabolites, namely, (R)-( )-mellein (8), (3R,4R)-4-hydroxymellein (9), (3R,4S)-4-hydroxymellein (10) (R)( )-3-hydroxymellein (11), belong to the family of dihydroisocoumarins; and two of the metabolites, namely, 6-methyl-salicylic acid (12) and 2-hydroxypropyl salicylic acid (13), belong to the family of hydroxybenzoic acids. We determined the phytotoxic activity of the isolated metabolites through a leaf disc assay and the expression of defence-related genes in Vitis vinifera cells cv. Chardonnay cultured with ( )-terremutin (1), the most abundant metabolite. Finally, analysis of the brown stripes of grapevine wood from plants showing botryosphaeria dieback symptoms revealed the presence of two of the isolated phytotoxins info:eu-repo/semantics/publishedVersion

Botryosphaeria dieback, esca and Eutypa dieback are three economic major grapevine trunk diseases that cause severe yield reduction in vineyards worldwide. The frequency of disease symptoms has increased considerably over the past decade, and no efficient treatment is currently available to control these diseases. The different fungi associated with grapevine trunk diseases mainly induce necrotic wood and characteristic foliar symptoms. In this context, fungi virulence factors and host invasion are not well understood. We hypothesise that extracellular proteins produced by Diplodia seriata and Neofusicoccum parvum, two causal agents associated with Botryosphaeria dieback, are virulence factors responsible for the pathogenicity. In our previous work, we demonstrated that the total extracellular compounds produced by N. parvum induced more necrosis on Chardonnay calli and triggered a different defence gene expression pattern than those produced by D. seriata. Furthermore, this aggressiveness was not clearly correlated with the production of mellein, a characteristic phytotoxin of Botryosphaeriaceae, in our in vitro calli model. To characterise other potential virulence factors and to understand the mechanisms of host invasion by the fungus, we evaluated the profile, quantity and the impact of extracellular proteins produced by these fungi on Vitis vinifera calli necrosis and defence gene expression. Our results reveal that, under the same conditions, N. parvum produces more extracellular proteins and in higher concentrations than D. seriata. With Vitis vinifera cv. Chardonnay cells, we showed that equivalent concentrations of proteins secreted by N. parvum were more aggressive than those of D. seriata in producing necrosis and that they clearly induced more grapevine defence genes.

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Three major grapevine trunk diseases, esca, botryosphaeria dieback and eutypa dieback, pose important economic problems for vineyards worldwide, and currently, no efficient treatment is available to control these diseases. The different fungi associated with grapevine trunk diseases can be isolated in the necrotic wood, but not in the symptomatic leaves. Other factors seem to be responsible for the foliar symptoms and may represent the link between wood and foliar symptoms. One hypothesis is that the extracellular compounds produced by the fungi associated with grapevine trunk diseases are responsible for pathogenicity. In the present work, we used Vitis vinifera cv. Chardonnay cells to test the aggressiveness of total extracellular compounds produced by Diplodia seriata and Neofusicoccum parvum, two causal agents associated with botryosphaeria dieback. Additionally, the toxicity of purified mellein, a characteristic toxin present in the extracellular compounds of Botryosphaeriaceae, was assessed. Our results show that the total extracellular compounds produced by N. parvum induce more necrosis on Chardonnay calli and induce a different defence gene expression pattern than those of D. seriata. Mellein was produced by both fungi in amounts proportional to its aggressiveness. However, when purified mellein was added to the culture medium of calli, only a delayed necrosis and a lower-level expression of defence genes were observed. Extracellular compounds seem to be involved in the pathogenicity of the fungi associated with botryosphaeria dieback. However, the doses of mellein used in this study are 100 times higher than those found in the liquid fungal cultures: therefore, the possible function of this toxin is discussed.

In the present work, we described the fate of proventitious epicormic buds on the trunks of 40-year-old Quercus petraea trees and in parallel the vascular trace they produced in the wood. Our results show that small and large individual epicormic buds can survive as buds for 40 years and that both are composed of a terminal meristem and scales. Meristematic areas are detected in the scale axils of small buds; in addition to these meristems the large buds also have secondary bud primordia. The small buds are connected to the pith of the main stem by a unique trace, whereas the large buds are connected by one or multiple traces. A single trace might imply that the whole bud is still alive and multiple traces might indicate that the terminal meristem has died. In the latter case, each trace is connected to a secondary bud of the large bud. The buds found in a cluster are composed of a terminal meristem and scales with axillary meristems in the scale axils. A cluster is connected to the pith of a stem either by a unique trace when it seems to be the result of partial abscission of an epicormic shoot or multiple traces when it might have originated from an epicormic bud in which the terminal meristem has died. Whatever the type of the bud, the vascular trace in the bark is composed of a cambium, secondary xylem and parenchyma cells and the trace present in the wood had parenchyma cells with vestiges of secondary xylem. Each year, the vascular trace should be produced in the bark by the cambium of the tree but not by the bud itself. On 40-year-old Q. petraea, we observed a proliferation of epicormic buds and in parallel a multiplication of the number of vascular traces in the trunk, but the knots caused by the traces of epicormic buds in the wood, either as individuals or in clusters, are minor since their colours are only slightly darker than those of woody rays and they are less than 2 mm in diameter. The knots will appear when epicormic buds develop into shoots.

PURPOSE To describe the optical coherence tomography (OCT) findings in two cases of hydroxychloroquine retinopathy. METHODS Two patients with hydroxychloroquine retinopathy at the bull's eye stage were identified. Each patient underwent rigorous historical questioning to rule out known causes of macular atrophy and to determine contributing factors. Comprehensive ocular examination was performed, including dilated biomicroscopic examination of the macula and indirect ophthalmoscopic evaluation of the retinal periphery. Additional evaluation included fundus color photography with fluorescein angiography and OCT. RESULTS Both patients had a medical history of arthritis treated by hydroxychloroquine (Nivaquine; total dose, 365 g). At the bull's eye stage, OCT confirms the presence of macular atrophy, as shown in our two cases. The retinal atrophy seems to be related to the whole thickness of the retinal layers. CONCLUSION We report the OCT findings of two cases of macular atrophy associated with hydroxychloroquine retinopathy.

The persistence of large epicormic shoots is one of the main factors that reduces timber quality and value in Quercus petraea. The early phases of epicormic shoot formation, i.e. the initiation of the epicormic buds, their survival and their proliferation over the years, are not clearly understood. In the present work, we studied the initiation of the axillary buds giving rise to epicormic buds and shoots, and followed their behaviour during the first 5 years using both scanning electron microscopy and light microscopy. Two types of proventitious epicormic buds have been identified. The first type has small axillary buds associated with the rings of bud-scale scars which are found at the base and tip of each growth unit. These buds are made of a terminal meristem surrounded only by scales; no leaf primordium is detected. During the second and third years of epicormic life, meristematic areas appear in the scale axil. Progressively, the meristematic areas organize into secondary bud primordia composed solely of the terminal meristem surrounded by scales. The second type of epicormic bud has secondary buds produced by a large axillary bud when this large bud either developed into a shoot or partially abscised. The epicormic potential in Q. petraea is characterized by a balance between the epicormic buds in apparent rest, enclosing meristematic areas and secondary bud primordia, and their mortality over the years.

International audience; Context While past studies on epicormics in oak (Quercus sp.) have focused on the effect of thinning on epicormic shoots emergence, the consequences of this emergence on the epicormic ontogeny and future wood quality have rarely been asked. Aims This paper aims to quantifying the relationship between past emergence and current composition of epicormics. Methods Three thinning experiments with Quercus petraea (Matt.) Liebl. or Quercus robur L. were investigated. Epicormic shoots were regularly tallied and epicormic composition recorded recently. Some logs were scanned using X-ray computed tomography (CT). Results Past tallies on both species were mainly and positively related to the current frequency of bud clusters and burls. This was due to the production of buds by epicormic shoots for only certain trees, as evidenced by CT, and mainly to correlated numbers of current epicormic shoots, bud clusters and burls, all originating from a past common set of buds and bud clusters. Conclusion The important tree effect on both species suggests that oak silviculture can be optimized by the early selection of crop trees with few epicormics and/or eventually a first and heavy thinning that helps in spotting remaining individuals being prone to the development of multiple epicormics.

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Among grapevine trunk diseases, esca proper and apoplexy commonly represent a threat for viticulture worldwide. To retrieve further information about the mechanisms activated in apoplectic and esca proper-affected plants, a two-dimensional gel electrophoresis (2-DE) based analysis was conducted on green stems from 26-year-old standing vines. Symptomatic and asymptomatic stems from both apoplectic (A) and esca proper-affected (E) plants compared to control (without visual symptom since 10 years) stems were studied. Thirty-three differentially expressed proteins were identified by nanoLC-MS/MS and included into three groups conceptually defined as proteins involved in (i) metabolism and energy, (ii) stress tolerance, and (iii) defense response. For nine of them, expression of the relative mRNA's was also monitored by qRT-PCR. Proteome variations were specifically related to apoplexy and esca proper but were more similar in asymptomatic stems than in the symptomatic ones. Remarkable quantitative differences were noted for several proteins in symptomatic stems according to the expressed form, A and E. Results further indicate that similar responses are likely activated in asymptomatic stems but a various quantitative expression is triggered upon onset of apoplexy or esca proper symptoms while both kind of plants are infected by the same pathogenic fungi.

Esca is a destructive disease in grapevines (Vitis vinifera L.) caused by at least three fungi and characterised by two different external symptoms, the apoplectic and leaf stripe form. This latter form can be discerned as soon as symptoms become visible, but the preceding discrete signs during incubation are poorly or not understood. To further understand the development of the leaf stripe form, the period preceding and following the appearance of symptoms was investigated by studying physiological and molecular markers associated with photosynthetic mechanisms and stress response. No perturbation of any targeted metabolism was observed in asymptomatic leaves of asymptomatic canes from vines showing the leaf stripe form of esca. Conversely, drastic alterations of photosynthesis functions were registered in presymptomatic leaves, as revealed by the decrease of gas exchange and chlorophyll fluorescence, and the repression of photosynthesis-related genes. These alterations were amplified during symptom development. Expression of defence-related genes was affected and detected early in presymptomatic leaves and amplified during symptom expression. Our results suggest that grapevines may react precociously by reducing photosynthesis and triggering defence mechanisms in response to the leaf stripe form of esca.

Fungicides are widely used to control pests in crop plants. However, it has been reported that these pesticides may have negative effects on crop physiology, especially on photosynthesis. An alteration in photosynthesis might lead to a reduction in photoassimilate production, resulting in a decrease in both growth and yield of crop plants. For example, a contact fungicide such as copper inhibits photosynthesis by destroying chloroplasts, affecting photosystem II activity and chlorophyll biosynthesis. Systemic fungicides such as benzimidazoles, anilides, and pyrimidine are also phytotoxic, whereas azoles stimulate photosynthesis. This article focuses on the available information about toxic effects of fungicides on photosynthesis in crop plants, highlighting the mechanisms of perturbation, interaction, and the target sites of different classes of fungicides.

Botrytis bunch rot of grapes is mainly controlled by applying fungicides at three crop stages: the end of flowering (BBCH 68), bunch closure (BBCH 77) and the beginning of veraison (BBCH 81). The phenylpyrroles derivative fludioxonil is among the most effective fungicides registered to control Botrytis cinerea. Its effectiveness was investigated in relation to spray timing, fungicide resistance and defence responses of grapevine. Frequencies of B. cinerea strains which were resistant to fungicides were evaluated at harvest. The frequencies of resistant phenotypes were similar in all treatments except for a class of multidrug resistant strains (MDR 1) whose frequency increased after fludioxonil applications. None of the treatments tested induced defence responses in flowers/berries after fungicide application, suggesting that fludioxonil effectiveness was not related to a stimulation of plant defence processes. The standard program of three fungicide applications provided the best control of B. cinerea in the Champagne region in comparison with a single treatment of fludioxonil at any of the crop stages tested.

Branch knots and other traces of lateral axes, known as rameal traces, have generally been disregarded within architectural studies based on external observations and their analysis limited to tedious manual dissection methods. Based on non-destructive methods including X-ray CT scanning (XRCTS) and on the ontogenic knowledge progressively accumulated on Quercus petraea, this paper presents (1) the tracking methodology of all rameal traces with XRCTS and the "Gourmands" plugin, and software created downstream, notably the 3D visualisation software "Bil3D"; (2) preliminary results obtained on two Quercus petraea 50 cm-long logs; and (3) potential applications in the fields of biology and ecology. Of approximately 45 sequences of linked rameal traces (composing rameal sequences) per metre, half were directly connected to the pith as horizontal traces of primary epicormic buds, while the other half were connected to a branch by an oblique knot. Horizontal epicormic knots essentially emerged within the tree from the most intensive thinning treatment and led to additional knots in the clear wood. Secondary epicormic shoots may emerge from branch and epicormic knots, leading to a vertical spread of epicormic sites for the former and to more bud clusters for the latter. Engulfment of lateral axes can be quantified. Assumptions on the origin of between-tree variability are proposed. Our methodology opens the way to an exhaustive description of rameal traces. It is relevant for ontogenic and wood quality assessment at the trunk level. It may also be very useful for characterising the potentiality of reiteration and for repairing shoot damage and vegetative regeneration at the crown, collar and even root system level.

Grapevine trunk diseases are very harmful to wine-growing heritage durability because the fungi responsible, by attacking perennial organs, cause at a more or less long-term the death of the vine stock. Esca and BDA are the two main pathogens inducing such decaying diseases. The infection can be diagnosed by the presence in the wood forming tissues of sectorial and/or central necrosis, which revealed itself by brown stripes or canker, and at the foliar level by discoloration and withering. This review presents an overview of both Esca and BDA, their symptomatology, the characteristics of the associated fungi and host-pathogen interactions. To conclude, a progress report on the control of both diseases is discussed.

To further understand the development of esca disease in grapevine, its physiological impact on plants grown in the vineyard was characterized, focusing mainly on photosynthesis. For this purpose, the state of the photosynthetic apparatus was evaluated in symptomatic and asymptomatic leaves in esca-infected grape plants, and wood carbohydrates stored in annual canes were assayed. In symptomatic leaves, esca greatly affected grapevine physiology. Foliar symptoms were associated with both stomatal closure and alteration of the photosynthetic apparatus as revealed by (i) a decrease in CO2 assimilation, transpiration, and a significant increase in intercellular CO2 concentration; (ii) a strong drop in both the maximum fluorescence yield and the effective Photosystem II quantum yield; and (iii) a reduction of total chlorophyll but a stable carotenoid content. On symptomatic canes, all these variables were affected more on leaves with symptoms than without symptoms, suggesting a gradation in photosynthesis disruptions in the plant according to the degree of symptom severity. In addition, canes of symptomatic plants had reduced carbohydrate reserves during the winter rest, whether they exhibit symptoms or not. The following year, the lower pool of reserves may contribute to a significant decrease in plant development, as well as a global loss in plant vigor.

The aim of this work was to determine the major limitations to photosynthesis induced by the fungicide fludioxonil (fdx) on nontarget grapevines using cutting as a model. The fdx treatments (1.2, 6, and 30 mM) induced a net photosynthetic rate ( P n) decrease without changes in stomatal conductance, suggesting a nonstomatal limitation. Fdx effects on P n were related neither to photosynthetic capacity alteration in leaves nor to loss in PSII activity. The mechanism underlying photosynthesis reduction differed according to the concentration. Fdx at 6 mM led to an increase of light requirement for photosynthesis while 30 mM fdx induced an increase in the respiration rate in the light. P n decrease after 1.2 mM fdx could rather be related to wetness caused by the spraying than to fungicide toxicity. P n recovered 10 days after treatment, meaning that fdx had little deleterious effect on plant physiology or that grapevine has a great capacity to overcome this temporary stress.

The aim of this study was to determine the impact of the fludioxonil (fdx) fungicide on the diurnal fluctuation in grapevine photosynthesis. Therefore, fdx treatment was performed at the end of flowering, at 8 am, 12 am or 7 pm. The study was performed in experimental field and several photosynthesis parameters were followed one day after treatment. Morning fdx treatment induced (i) a significant and simultaneous drop of both photosynthesis (Pn) and stomatal conductance between 8 am and 4 pm and (ii) an increase of intercellular CO(2) concentration when compared to control plants. On the contrary, evening fdx treatment did not affect Pn whereas midday treatment caused Pn increase after 4 pm. These data suggest that (i) morning fdx treatment results in a non-stomatal limitation of Pn, (ii) midday treatment is more suitable to treat grapevine with fdx and (iii) a phenomenon of gating was noticed.

• Epicormics are important defects of oak timber which originate from suppressed buds placed early and develop into epicormic shoots depending on the light available, which in turn depends on stand density. In this context, our objective was to assess the epicormic shoots present in a 20-year-old experimental plantation of sessile oak and to test and quantify the effect of the three initial densities applied: 1333, 2667 and 5333 stems/ha. • In the 3 stand densities, epicormic shoots were mostly transient and were rarely clustered. A significant but negligible effect of the density on the epicormic length and on the variables related to epicormic counts appeared: the longest epicormic shoots were present in densities 1333 and 2667 while their means were significantly lower for density 5333. When considering the tree descriptors, the best explanatory models of the different epicormic counts involved their relative variations, especially the relative increment (RIV) in the product V = HEIGHT.DBH2. More precisely, emergence of epicormic shoots occurred particularly when trees fell below a threshold value of RIV = 0.26. Such trees belonged mainly to the two highest densities: 2667 and 5333 stems/ha. • When considering only epicormics, none of the tested densities can be recommended. Trees which bear the most numerous epicormic shoots will be naturally eliminated by stand competition.

Among the herbicides used in vineyards, the pre-emergence soil-applied flumioxazin (fmx) is a recently used molecule that inhibits chlorophyll biosynthesis in weed species. The aim of this work is to further characterize the effects of fmx on the non-target grapevine ( Vitis vinifera L. cv. Chardonnay) using cutting as a model. Several photosynthesis parameters were estimated during 25 days after treatment with various fmx concentrations (from 0.5 mM to 50 mM). Measuring chlorophyll fluorescence it appeared that fmx or a by-product penetrated the plant throughout roots and spread throughout vessels. Besides the initial target, protox, fmx affected other functions related to photosynthesis. Fmx induced a simultaneous drop of both P n , g s and T . Fmx caused stomatal closure, which partially explains the decrease of the net photosynthesis. The decline in F v / F m indicates that the photochemistry of PSII and its ability to reduce the primary acceptor Q A are also affected by fmx in grapevine. Fmx leads to a decrease in the coefficients of both photochemical and non-photochemical quenching. Simultaneous stomatal closure and decrease in the quantum yield of CO 2 assimilation indicate a change in energy metabolism following fmx stress. After ten days of fmx treatment, analyses of the response of net carbon assimilation in leaves to different intercellular CO 2 concentrations have shown a decrease of the maximum carboxylation velocity of RuBP. Stomatal closure, PSII photochemistry, change in energy metabolism and RuBP activity were affected by fmx treatment.

Aim: The present study was conducted in grapevines to evaluate the influence of source/sink disturbance on reserve restoration in the entire plant (trunk, roots) and the consequences on reproduction, yield, sugar yield, potential alcohol content and total acidity over four successive years of treatment.Methods and results: At véraison, either total defoliation or total fruit removal was performed on Chardonnay plants grown in vineyards. The impact was measured each year on reproductive parameters and after four years on both plant weight and carbohydrate content. Defoliation induced an alteration in carbohydrate distribution in the entire plant, as revealed by decrease of starch content and parallel increase of soluble sugar content. These modifications affected the number of inflorescences/clusters per plant the year after. By contrast, fruit removal resulted in a significant increase of carbohydrate reserves in the whole plant, although the efficiency of sexual reproduction was not improved the year after.Conclusion: Results confirm the close correlation between carbohydrate reserves and the efficiency of sexual reproduction. Moreover, grapevine is able to adapt the number of both inflorescences and flowers according to the amount of available carbohydrate reserves in perennial organs.Significance and impact of the study: The quality of the crop is affected by defoliation, as shown by the decrease in yield and sugar yield. However, the impact on potential alcohol content and total acidity was less pronounced.

Les arbres d'une plantation de Chene pedoncule (Quercus robur L.) de 16 ans dans le Nord-Est de la France, realisee avec des plants mycorhizes ou non par le champignon Paxillus involutus, ont ete etudies du point de vue de la croissance, de l'elagage naturel et des gourmands. Les resultats montrent que la stimulation de croissance initiale se traduit encore par un effet significatif sur la hauteur totale, mais que le traitement fongique n'a plus d'effet sur la hauteur ou le diametre de la premiere branche vivante. Les arbres initialement mycorhizes par Paxillus involutus tendent a avoir plus de gourmands, avec une frequence plus elevee de gourmands groupes. Cependant, la plupart de ces gourmands sont petits et de duree de vie tres limitee, et la conclusion generale est que le gain de croissance procure par la mycorhization controlee n'est en rien compromis par d'eventuels effets secondaires pouvant deprecier la qualite des tiges.

The epicormic potential was represented by the number of visible epicormic buds (primary and secondary) present at a given time and on a given length of stem. Data were collected from sixty-six 4-year-old annual shoots on 17-year-old Quercus petraea with 3 stand densities. We estimated the epicormic potential in 1997 and then followed its evolution over the next 2 years. Preliminary results showed that the epicormic potential decreased from 1997 to 1999, independently to the stand density. The loss of epicormic buds (death or development into shoots) was not compensated by the production of new epicormic buds. Furthermore, we report that the composition of the epicormic potential was unchanged for these 2 years: one third were primary epicormic buds and two thirds were secondary epicormic buds. Secondary epicormic buds were mainly found as individual and located at the base of branches. No formations of large clusters of epicormic buds were observed., Le potentiel épicormique est représenté par le nombre de bourgeons épicormiques visibles (primaires et secondaires) présents à un moment donné sur une unité de longueur définie. Les données ont été collectées sur la pousse annuelle âgée de 4 ans de 66 chênes sessiles âgés de 17 ans répartis dans 3 densités de culture. Nous avons évalué le potentiel épicormique en 1997 puis nous avons suivi son évolution les 2 années suivantes. Les premiers résultats ont montré que le potentiel épicormique a diminué de 1997 à 1999, indépendamment des densités de culture. La perte de bourgeons épicormiques (mort ou développement en gourmands) n’a pas été compensée par la formation de nouveaux bourgeons épicormiques. De plus, nous avons constaté que la composition du potentiel épicormique restait inchangée au cours de ces 2 années et comprenait toujours un tiers de bourgeons épicormiques primaires et deux tiers de bourgeons épicormiques secondaires. Ces derniers étaient essentiellement isolés et localisés à la base des branches. Aucune formation de groupes de bourgeons n’a été observée.

Article n°3; International audience; The provenance effect on epicormics is poorly documented and restricted to epicormic shoots. Our objective was to characterize the relationship between epicormics and provenance on 13-year-old Quercus petraea trees, taking into account their growth traits.* On the growth units (GU) studied, epicormics were essentially isolated buds (95%) and they were mainly located at branch bases, secondarily on GU limits and marginally on lateral position. Provenance effect was very small on the number of epicormics and slightly larger on the number of branches and GU limits. On the contrary, the growth situation -independently from provenance- proved to have a larger effect on the 2 latter growth traits.* Altogether, these results clearly show the predominant effect of morphological traits and thus of ontogeny. This opens important research perspectives: how growth conditions and genetics (at progeny and individual levels) influence height growth, setting and fate of axillary buds on the one hand and fate of epicormic buds inserted directly on the stem, or at branch bases on the other hand.; L'effet provenance sur les épicormiques est peu documenté et concerne exclusivement les gourmands. Notre objectif était de caractériser l'effet de la provenance sur les épicormiques présents sur des chênes sessiles âgés de 13 ans, décrits par des marqueurs de croissance.* Sur les unités de croissance (UC) décrites, les épicormiques sont essentiellement des bourgeons isolés (95 %), localisés à la base de branche, puis en limite d'UC et enfin en position latérale sur le tronc. L'effet provenance s'est avéré très faible sur le nombre d'épicormiques et légèrement plus fort sur le nombre de branches et d'UC développées. À l'inverse, un effet de la situation de croissance a été noté sur les deux derniers paramètres, et ceci indépendamment de la provenance.* L'ensemble des données obtenues montre une prédominance de l'effet des marqueurs morphologiques de l'arbre sur les épicormiques, et donc de l'ontogénèse. Ceci ouvre d'intéressantes perspectives de recherche : quels sont les effets des conditions de croissance et de la génétique (au niveau descendance et individuel) sur la croissance en hauteur, la mise en place et le devenir des bourgeons axillaires d'une part, et du devenir des bourgeons épicormiques, situés directement sur la tige ou en base de branches séquentielles d'autre part.

International audience; Effects of thinning on epicormics have rarely been demonstrated especially due to inaccurate surveying methods. * Our objective was to assess the effect of contrasted thinnings on the ontogeny of epicormics on sessile oak. We used the epicormic composition defined as the arrangement of epicormics in different classes (isolated bud, clustered buds, short and long shoots and "picots") and quantified by the total frequency of epicormics and the proportion of each class. * Epicormic composition was recorded in a silvicultural experiment testing highly contrasted thinnings, at 3 different stand stages and on lower (0.5-3 m) and upper (3-6 m) boles. Ageing provoked an accumulation of bud clusters and of picots. After thinning, epicormic shoots emerged mainly from (1) still present short epicormic shoots, (2) buds either isolated or in clusters depending on the stand stage. Upper boles bore epicormic compositions close to those observed on lower boles in the few preceding years. Upper logs were more reactive than lower boles. * To conclude, the epicormic composition was a relevant tool to follow the dynamics of the epicormic ontogeny and to demonstrate the effects of thinning on it.

The objective of this work was to determine the preformed or neoformed nature of the three successive growth units occurring in 1 year on the leader shoot of 3-year-old Quercus petraea (Matt.) Liebl. seedlings in 1997 and 1998. We compared the number of foliar organs between the first, second, and third growth units and their respective terminal buds. The foliar organs counted on the growth units were basal scales or scaly leaves and photosynthetic leaves, and the foliar organs counted within the buds were future photosynthetic leaves, undetermined foliar organs, and internal scales that indicated a period of rest. The results were (i) the winter terminal bud enclosed internal scales, and it possessed more foliar organs than the first growth unit; (ii) the terminal bud of the first growth unit did not contain any internal scales, and it possessed fewer foliar organs than the second growth unit; and (iii) the terminal bud of the second growth unit sometimes contained one or more internal scales, and it possessed fewer or the same number of foliar organs than the third growth unit. These results showed that (i) the first growth unit is entirely preformed in the winter bud, (ii) the second growth unit possesses both preformed and neoformed portions, and (iii) the third growth unit could be either totally preformed, or partially preformed and partially neoformed. Neoformation is more prevalent in the second growth unit than in the third. The difference between the total number of foliar organs in the bud and on the growth unit is more pronounced in the second growth unit than in the third.

National audience; Dans le cadre du projet CASDAR V1301, l’impact d’un traitement à l’arsénite de sodium sur la physiologie de la vigne a été étudié chez le Chardonnay. Deux approches complémentaires, transcriptomique et métabolomique, ont été réalisées sur différents organes (tiges herbacées et tronc en distinguant le bois sain et la zone d’interaction bois sain / bois altéré) de ceps non traités sans symptômes foliaires (témoins), non traités avec symptômes foliaires et traités (n’exprimant donc plus les symptômes et qualifiés de « guéris »). Les échantillons ont été prélevés 6 mois après le traitement (avant vendanges). Parmi les principaux résultats, l’analyse transcriptomique montre que les tiges herbacées présentent des différences d'expression des gènes plus importantes que le bois. Ainsi, les ceps témoins et malades ont des profils d'expression spécifiques et le traitement arsénite conduit lui aussi à un profil d'expression particulier. Parmi ces gènes, nous avons pu identifier un groupe ayant une réponse de type « stigmate de l'infection », car ils sont différentiellement exprimés chez les ceps malades par rapport aux ceps témoins et de façon similaire chez les ceps malades et les ceps « guéris» par le traitement arsénite. Un autre groupe de gènes présente une réponse de type « guérison», car ils sont différentiellement exprimés chez les ceps malades par rapport aux ceps témoins, et avec le même profil d’expression chez les ceps témoins et les ceps ayant été traités à l’arsénite. Ces expériences montrent que l’infection du bois de la vigne a un impact important sur la physiologie des parties aériennes et qu’il est ainsi possible d’identifier des gènes marqueurs de l’infection au niveau de la tige herbacée. De plus, le traitement à l’arsénite a un effet important sur le transcriptome de la vigne et certains gènes pourraient être considérés comme des marqueurs de la « guérison » de la vigne. En complément, l’analyse métabolomique nous a permis de mettre en évidence des signatures métaboliques spécifiques du traitement arsénite tant au niveau des tiges herbacées que des zones ligneuses (zones d'interaction bois sain altéré). Le traitement arsénite impacte donc aussi le métabolome de la vigne et de potentiels métabolites marqueurs de « guérison » sont en cours d’identification. La détermination d’indicateurs de « guérison », gènes et ou métabolites, permettrait de tester plus facilement l’efficacité de futures stratégies de protection contre l’esca. Enfin l’impact du traitement arsénite s'est également confirmé à l'échelle cellulaire (histologie) où des réponses structurales et défensives sont encore observées, 7 mois post-traitement, dans les différents compartiments de la plante.