Olivier Viret | Swiss Federal Institute of Technology (ETH) (original) (raw)

Papers by Olivier Viret

Research paper thumbnail of Registration of plant protection products in EPPO countries: current status and possible approaches to harmonization

EPPO Bulletin, 2001

ABSTRACT A survey concerning registration of plant protection products was carried out in 41 EPPO... more ABSTRACT A survey concerning registration of plant protection products was carried out in 41 EPPO member countries. Twenty six countries responded and results are summarized in three groups. Various models are discussed which seek to adapt product dosage to the crowns of fruit-tree crops. The tree row volume model (TRV) is favoured by the authors since it can adequately cope with the wide variability of orchards encountered across Europe. It is suggested that experimenters who carry out registration field trials should measure the height and width of the tree crowns and the distance between the tree rows to facilitate comparison of registration trials including residue data.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Physiological consequences of vine defoliation – a review

Leaf removal is a common practice in northern vineyards. This review of literature aims at gather... more Leaf removal is a common practice in northern vineyards. This review of literature aims at gathering the knowledge about this cultivation technique. The different defoliation periods are reviewed. Risks (flower abortion, sun burn) and advantages (rot control) of this process are also presented giving a particular attention to the compensatory physiological mechanisms following vine defoliation. Earlier is defoliation realized, more significant will be the consequences on the vine physiology. The link between defoliation and must quality is discussed. There is an actual revival of interest in early defoliation before berry set as a way to increase the quality potential of wines in terms of aromas and polyphenols.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Performance of the cv. Pinot Noir under the pedoclimatic conditions of the Valais area, Switzerland Etude comportementale du Pinot noir dans les conditions pédo-climatiques du vignoble valaisan

In 2005, 2006 and 2008, a study was conducted on the physiologic and agronomic behaviour of Pinot... more In 2005, 2006 and 2008, a study was conducted on the physiologic and agronomic behaviour of Pinot noir under several pedoclimatic conditions of the Valais area (Switzerland). For this purpose, 11 plots spread out over the 60 km between Martigny and Sierre, were chosen with homogeneous material of Pinot noir cultivar. The agronomic development of the grapevines was monitored. Furthermore, grapes were vinified with the aim of carrying out chemical and sensory analysis. The three vintages have been characterized by a low to moderate water constraint and abundant nitrogen nutrition of the vines. In the absence of pronounced water restriction, the phenology and the speed of development have been correlated to temperature according to the altitude of sites, from 450 to 900 meters above sea level. Vines planted in higher water reserve soils have shown more important vigour along with higher nitrogen content in leaves and must. Anthocyanin content was higher in wines when vines had previous...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Influence of rootstock on agronomical behaviour of cv. Gamaret in Ticino

Two trials on the association of the cv. Gamaret with several rootstocks were conducted in the vi... more Two trials on the association of the cv. Gamaret with several rootstocks were conducted in the vineyards of Ticino with the aim of improving its vegetative behavior and productivity. Under less fertile soils conditions, more vigorous rootstocks (5 BB or SO4) significantly improved the homogeneity of growth and vigour of the cultivar and could be recommended instead of the traditional 3309 C. But on fertile soils where 3309 C gives a sufficient vigor, those rootstocks are not recommended because they enhance the risk of higher flower abortion and poor fruit set during the years with unfavorable weather during the flowering period.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Nitrogen dilution in excessive canopy of cvs. Chasselas and Pinot noir

Journal International des Sciences de la Vigne et du Vin

Aims: The impact of canopy management on the nitrogen (N) content in grapevines was studied. Meth... more Aims: The impact of canopy management on the nitrogen (N) content in grapevines was studied. Methods and Results: Two trials were carried out between 2001 and 2010 on Vitis vinifera cvs. Chasselas and Pinot noir. The observed factors of variation were the intensity of lateral shoot removal for the first trial and the severity of shoot trimming for the second trial. The N content was evaluated in parallel by leaf diagnosis, the chlorophyll index and the yeast available N concentration (YAN) found in the musts. When the yields were the same, a significant dilution of N in proportion to the development of the leaf area was revealed. Treatments resulting in excessive leaf area presented N deficiency in the leaves and the musts. Conclusion: The N content in both the vines and grapes was influenced by the canopy management (lateral shoot removal and shoot trimming), and the magnitude of the response appeared to be even greater in the absence of water stress. In addition, the risk of N def...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of What if esca disease of grapevine were not a fungal disease?

Fungal diversity

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Current status of major grapevine viruses in La Côte vineyards of Switzerland

Viral diseases are reported to cause several detrimental effects on grape and wine production. In... more Viral diseases are reported to cause several detrimental effects on grape and wine production. In order to evaluate the distribution of these pathogens, a survey was undertaken in the vineyards of La Côte in the Swiss canton of Vaud. Results from this survey showed that major viral diseases are widespread in vineyards, particularly leafroll and fanleaf. A recently described virus, Grapevine Pinot gris-associated virus (GPGaV), has been detected for the first time in Swiss vineyards. Considering those results, there is little doubt that it is important to use virus free plant from certificated material and that grapevine certification program is of paramount importance for a sustainable wine production.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Development of a rapid and highly sensitive direct-PCR assay to detect a single conidium of Botrytis cinerea Pers.:Fr in vitro and quiescent forms in planta

Direct-PCR" amplifications of Botrytis cinerea-spe-cific genomic sequences, without any DNA ... more Direct-PCR" amplifications of Botrytis cinerea-spe-cific genomic sequences, without any DNA purification step or time consuming sample preparation, were developed. A single copy sequence of 0.7 Kb in the Botrytis cinerea ge-nome was amplified in reactions containing no more than 1 x 10 5 to 1 single conidium. As a demonstrative applica-tion, this assay was applied to detect B. cinerea in different parts of immature grape berries (at 'pea size'), when previ-ously inoculated with conidia at flowering. Using this method we showed the presence of quiescent Botrytis in the receptacle area only. Cloning and sequencing of the frag-ment confirmed the single sequence gene of B. cinerea. These results demonstrate that the method is easy to apply and of sufficiently high sensitivity to detect the presence of B. cinerea in immature grape berries. Its use for studies on the development of grey mould and improved control of the disease in vineyards is discussed. K e y w o r d s : Bot...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of „VitiMeteo Plasmopara“ – Prognosemodell zur Bekämpfung von Plasmopara viticola (Rebenperonospora) im Weinbau

Gesunde Pflanzen, 2008

Zusammenfassung Die Rebenperonospora (Erreger: Plasmopara viticola) ist die wirtschaftlich bedeu... more Zusammenfassung Die Rebenperonospora (Erreger: Plasmopara viticola) ist die wirtschaftlich bedeutendste Rebkrankheit in humiden Weinanbaugebieten. Das computergestützte Modell „VitiMeteo Plasmopara“ berechnet mit Wetterdaten die wichtigsten Entwicklungsschritte im Lebenskreislauf der Rebenperonospora. Ein witterungsabhängiges Modell für den Blattzuwachs ergänzt das reine Prognosemodell für Rebenperonospora. „VitiMeteo Plasmopara“ wurde vom Staatlichen Weinbauinstitut Freiburg gemeinsam mit den Schweizer Forschungsanstalten „Agroscope“ Wädenswil und Changins erstellt. Das System wird

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Evidence for a Constitutive Cutinase in Ungerminated Conidia of Erysiphe necator Schwein

Journal of Cytology & Histology, 2013

ABSTRACT Soluble proteins of ungerminated conidia of Erysiphe necator exhibited esterase and cuti... more ABSTRACT Soluble proteins of ungerminated conidia of Erysiphe necator exhibited esterase and cutinase activities, and such hydrolytic activities were measured in the parietal protein fraction. However, histochemical localisation of esterase activity was detected upon further fungal development, as well in elongating germ tubes and in appressoria. The esterase activity was spectrophotometrically quantified using para-nitrophenylbutyrate as a substrate, and cutinase activity was determined using 3H-labelled cutin. Histochemical localisation was determined using indoxyl acetate as a substrate. Diisopropyl fluorophosphate was used as inhibitor of serine hydrolase. The role of a putative constitutive parietal cutinase in the ungerminated conidia of E. necator in adhesion to the host and differentiation of infective structures, as well as implications for successful penetration, are discussed.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Role of stilbenes in the resistance of grapevine to powdery mildew

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effect of fertilisation timing on the partitioning of foliar-applied nitrogen in V itis vinifera cv. Chasselas: a 15 N labelling approach

Australian Journal of Grape and Wine Research, 2015

ABSTRACT Background and AimsYeast assimilable nitrogen (YAN) in grape must is an important determ... more ABSTRACT Background and AimsYeast assimilable nitrogen (YAN) in grape must is an important determinant of wine composition. The effect of foliar nitrogen fertilisation on YAN concentration in must of Vitis vinifera L. cv. Chasselas was studied. Nitrogen assimilation and translocation were investigated by applying 15N-labelled urea at flowering and at veraison.Methods and ResultsFoliar urea was applied on field-grown Chasselas grapevines using labelled (10 atom% 15N) and unlabelled urea. The vines were excavated at harvest, and plant parts were separated and analysed. Thus, the distribution of dry organic matter and of total organic carbon and total organic nitrogen in the plant at harvest was determined. Bunches were the strongest N sink among all of the organs during both fertilisation periods. The highest YAN in the must, however, was obtained when the urea was applied during veraison.Conclusions Isotope labelling was used to describe N partitioning throughout the vine in response to foliar nitrogen fertilisation with urea at flowering and at veraison. Differences between organs in carbon and nitrogen isotope discrimination at natural abundance were established. Fertilisation with urea during veraison increased the YAN concentration in Chasselas grape must.Significance of the StudyResults show that it is more effective to correct YAN deficiency in the vineyard with application of foliar urea during veraison than during flowering.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Induction of defence mechanisms in grapevine leaves by emodin- and anthraquinone-rich plant extracts and their conferred resistance to downy mildew

Plant Physiology and Biochemistry, 2009

The ability of two plant extracts, Rheum palmatum root extract (RPRE) and Frangula alnus bark ext... more The ability of two plant extracts, Rheum palmatum root extract (RPRE) and Frangula alnus bark extract (FABE), to protect Vitis vinifera leaves from Plasmopara viticola infection was evaluated. These natural products are toxic to the pathogen and induce defence reactions in a susceptible cultivar of V. vinifera (V. vinifera cv. Chasselas), including stilbenic phytoalexin accumulation, enhanced peroxidase (EC 1.11.1.7) activity, and a hypersensitive reaction. Inhibition of the first stage of biotrophic hyphal development of P. Viticola by the two plant extracts was observed. HPLC-DAD-MS analysis showed that these two natural extracts contain many phenolic compounds belonging to the anthraquinone family, such as rhein, frangulin A, emodin, aloe-emodin, chrysophanol, and physcion. Emodin alone is able to impair P. viticola development and to stimulate viniferins and the accumulation of pterostilbene.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Susceptibility to downy mildew in grape clusters: New microscopical and biochemical insights

Plant Physiology and Biochemistry, 2012

Grape clusters of different Vitis genotypes, including Vitis vinifera cvs Chasselas and Merlot, a... more Grape clusters of different Vitis genotypes, including Vitis vinifera cvs Chasselas and Merlot, and two interspecific grape varieties, Solaris (cvs. Merzling* x (Saperavi severneyi x Muscat ottonel)) and 2091 (cvs. Gamaret x Bronner), are susceptible or resistant to downy mildew. These cultivars were inoculated with Plasmopara viticola at three developmental stages (BBCH stages 53, 69 and 75). Samples were examined by scanning electron microscopy and the synthesis of stilbenes was measured. Microscopical examinations of pedicels, rachis and calyptras showed important differences in stomatal structures within seasonal development. At BBCH 53, successful infections were observed on all tested cultivars and functional stomata were present, while no infections were observed after this stage. At BBCH 69 and 75, cracks were observed around the stomata and guard cells were unstructured or completely collapsed, leading to closed-like stomata. At BBCH 53, significant stilbene accumulation was quantified in 2091 and Solaris; pterostilbene and δ-viniferin were produced in large amounts. In the susceptible varieties, only piceid and resveratrol were induced. At the other two stages, the concentration of all measured stilbenes was undetectable. The critical roles of seasonal development and stilbenes in the resistance of grape clusters towards downy mildew are discussed.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Stilbenes: Biomarkers of Grapevine Resistance to Disease of High Relevance for Agronomy, Oenology and Human Health

Plant Defence: Biological Control, 2011

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Characterization of 3 new partial stilbene synthase genes out of over 20 expressed in Vitis vinifera during the interaction with Plasmopara viticola

Physiological and Molecular Plant Pathology - PHYSIOL MOLEC PLANT PATHOL, 2005

RT-PCR was used to amplify stilbene synthase (STS) transcripts expressed in the grape–downy milde... more RT-PCR was used to amplify stilbene synthase (STS) transcripts expressed in the grape–downy mildew interaction. Four grape cultivars, Chasselas, IRAC-2029, IRAC-1999 and Solaris (from susceptible to resistant), were used in order to access members of the gene family and some allelic variations. Plant resistance to Plasmopara viticola was scored by quantification of stilbenes 2 days post inoculation and of sporangia at 7 days. RT-PCR products were analyzed by gel electrophoresis, cloned and 300 individual clones were sequenced. Sequences covered 1/3 (455 bp) of the coding region and up to 300 bp of the 3′ untranslated region. A cluster tree of the aligned sequences exhibits 17 main branches, most of which split again suggesting allelic variations. Quantitative real-time PCR was then performed to identify single copy genes coding for STS as well as for the closely related chalcone synthase (CHS). The analysis identified that grapes have two CHS, one CHS-like and close to 25 STS single copy genes. A comparison between a sensitive and a resistant grape to P. viticola is discussed in relation to the stilbene synthase gene family and the problematic to quantify their expression.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A comprehensive metabolomic study of wine from the Vaud Switzerland vineyard

Planta Medica, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Protease inhibitors decrease the resistance of Vitaceae to Plasmopara viticola

Plant Physiology and Biochemistry, 2012

Plasmopara viticola must successfully infect susceptible grapevine cultivars to complete its biol... more Plasmopara viticola must successfully infect susceptible grapevine cultivars to complete its biological cycle. In resistant grapevine varieties, P. viticola is blocked by the activation of defense mechanisms; these defense mechanisms produce hypersensitive reactions, which are related to programmed cell death. In animals, programmed cell death is dependent on caspase activities. In plants, different caspase-like proteases assume the same functions. To examine the roles of caspase-like proteases in P. viticola-grapevine interactions, three varieties of grapevine with different levels of P. viticola resistance were chosen. These grapevine varieties were treated with either PMSF, a serine protease inhibitor, or E-64, a cysteine protease inhibitor. The development of the pathogen was followed microscopically, and the plant defense reactions were estimated through stilbene quantification. Both protease inhibitor treatments increased the infection rate in the resistant and immune varieties, diminished the production of toxic stilbenes and changed the level of the plants' susceptibility to the pathogen. In particular, after either protease treatment, the cultivar that was originally immune became resistant (hyphae and haustoria were observed), the resistant cultivar reached the level of a susceptible cultivar (sporulation was observed) and the susceptible cultivar became more sensitive (P. viticola colonized the entirety of the leaf mesophyll).

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Histological study of the responses of two Vitis vinifera cultivars (resistant and susceptible) to Plasmopara viticola infections

Plant Physiology and Biochemistry, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The effectiveness of stilbenes in resistant Vitaceae: Ultrastructural and biochemical events during Plasmopara viticola infection process

Plant Physiology and Biochemistry, 2011

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Registration of plant protection products in EPPO countries: current status and possible approaches to harmonization

EPPO Bulletin, 2001

ABSTRACT A survey concerning registration of plant protection products was carried out in 41 EPPO... more ABSTRACT A survey concerning registration of plant protection products was carried out in 41 EPPO member countries. Twenty six countries responded and results are summarized in three groups. Various models are discussed which seek to adapt product dosage to the crowns of fruit-tree crops. The tree row volume model (TRV) is favoured by the authors since it can adequately cope with the wide variability of orchards encountered across Europe. It is suggested that experimenters who carry out registration field trials should measure the height and width of the tree crowns and the distance between the tree rows to facilitate comparison of registration trials including residue data.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Physiological consequences of vine defoliation – a review

Leaf removal is a common practice in northern vineyards. This review of literature aims at gather... more Leaf removal is a common practice in northern vineyards. This review of literature aims at gathering the knowledge about this cultivation technique. The different defoliation periods are reviewed. Risks (flower abortion, sun burn) and advantages (rot control) of this process are also presented giving a particular attention to the compensatory physiological mechanisms following vine defoliation. Earlier is defoliation realized, more significant will be the consequences on the vine physiology. The link between defoliation and must quality is discussed. There is an actual revival of interest in early defoliation before berry set as a way to increase the quality potential of wines in terms of aromas and polyphenols.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Performance of the cv. Pinot Noir under the pedoclimatic conditions of the Valais area, Switzerland Etude comportementale du Pinot noir dans les conditions pédo-climatiques du vignoble valaisan

In 2005, 2006 and 2008, a study was conducted on the physiologic and agronomic behaviour of Pinot... more In 2005, 2006 and 2008, a study was conducted on the physiologic and agronomic behaviour of Pinot noir under several pedoclimatic conditions of the Valais area (Switzerland). For this purpose, 11 plots spread out over the 60 km between Martigny and Sierre, were chosen with homogeneous material of Pinot noir cultivar. The agronomic development of the grapevines was monitored. Furthermore, grapes were vinified with the aim of carrying out chemical and sensory analysis. The three vintages have been characterized by a low to moderate water constraint and abundant nitrogen nutrition of the vines. In the absence of pronounced water restriction, the phenology and the speed of development have been correlated to temperature according to the altitude of sites, from 450 to 900 meters above sea level. Vines planted in higher water reserve soils have shown more important vigour along with higher nitrogen content in leaves and must. Anthocyanin content was higher in wines when vines had previous...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Influence of rootstock on agronomical behaviour of cv. Gamaret in Ticino

Two trials on the association of the cv. Gamaret with several rootstocks were conducted in the vi... more Two trials on the association of the cv. Gamaret with several rootstocks were conducted in the vineyards of Ticino with the aim of improving its vegetative behavior and productivity. Under less fertile soils conditions, more vigorous rootstocks (5 BB or SO4) significantly improved the homogeneity of growth and vigour of the cultivar and could be recommended instead of the traditional 3309 C. But on fertile soils where 3309 C gives a sufficient vigor, those rootstocks are not recommended because they enhance the risk of higher flower abortion and poor fruit set during the years with unfavorable weather during the flowering period.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Nitrogen dilution in excessive canopy of cvs. Chasselas and Pinot noir

Journal International des Sciences de la Vigne et du Vin

Aims: The impact of canopy management on the nitrogen (N) content in grapevines was studied. Meth... more Aims: The impact of canopy management on the nitrogen (N) content in grapevines was studied. Methods and Results: Two trials were carried out between 2001 and 2010 on Vitis vinifera cvs. Chasselas and Pinot noir. The observed factors of variation were the intensity of lateral shoot removal for the first trial and the severity of shoot trimming for the second trial. The N content was evaluated in parallel by leaf diagnosis, the chlorophyll index and the yeast available N concentration (YAN) found in the musts. When the yields were the same, a significant dilution of N in proportion to the development of the leaf area was revealed. Treatments resulting in excessive leaf area presented N deficiency in the leaves and the musts. Conclusion: The N content in both the vines and grapes was influenced by the canopy management (lateral shoot removal and shoot trimming), and the magnitude of the response appeared to be even greater in the absence of water stress. In addition, the risk of N def...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of What if esca disease of grapevine were not a fungal disease?

Fungal diversity

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Current status of major grapevine viruses in La Côte vineyards of Switzerland

Viral diseases are reported to cause several detrimental effects on grape and wine production. In... more Viral diseases are reported to cause several detrimental effects on grape and wine production. In order to evaluate the distribution of these pathogens, a survey was undertaken in the vineyards of La Côte in the Swiss canton of Vaud. Results from this survey showed that major viral diseases are widespread in vineyards, particularly leafroll and fanleaf. A recently described virus, Grapevine Pinot gris-associated virus (GPGaV), has been detected for the first time in Swiss vineyards. Considering those results, there is little doubt that it is important to use virus free plant from certificated material and that grapevine certification program is of paramount importance for a sustainable wine production.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Development of a rapid and highly sensitive direct-PCR assay to detect a single conidium of Botrytis cinerea Pers.:Fr in vitro and quiescent forms in planta

Direct-PCR" amplifications of Botrytis cinerea-spe-cific genomic sequences, without any DNA ... more Direct-PCR" amplifications of Botrytis cinerea-spe-cific genomic sequences, without any DNA purification step or time consuming sample preparation, were developed. A single copy sequence of 0.7 Kb in the Botrytis cinerea ge-nome was amplified in reactions containing no more than 1 x 10 5 to 1 single conidium. As a demonstrative applica-tion, this assay was applied to detect B. cinerea in different parts of immature grape berries (at 'pea size'), when previ-ously inoculated with conidia at flowering. Using this method we showed the presence of quiescent Botrytis in the receptacle area only. Cloning and sequencing of the frag-ment confirmed the single sequence gene of B. cinerea. These results demonstrate that the method is easy to apply and of sufficiently high sensitivity to detect the presence of B. cinerea in immature grape berries. Its use for studies on the development of grey mould and improved control of the disease in vineyards is discussed. K e y w o r d s : Bot...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of „VitiMeteo Plasmopara“ – Prognosemodell zur Bekämpfung von Plasmopara viticola (Rebenperonospora) im Weinbau

Gesunde Pflanzen, 2008

Zusammenfassung Die Rebenperonospora (Erreger: Plasmopara viticola) ist die wirtschaftlich bedeu... more Zusammenfassung Die Rebenperonospora (Erreger: Plasmopara viticola) ist die wirtschaftlich bedeutendste Rebkrankheit in humiden Weinanbaugebieten. Das computergestützte Modell „VitiMeteo Plasmopara“ berechnet mit Wetterdaten die wichtigsten Entwicklungsschritte im Lebenskreislauf der Rebenperonospora. Ein witterungsabhängiges Modell für den Blattzuwachs ergänzt das reine Prognosemodell für Rebenperonospora. „VitiMeteo Plasmopara“ wurde vom Staatlichen Weinbauinstitut Freiburg gemeinsam mit den Schweizer Forschungsanstalten „Agroscope“ Wädenswil und Changins erstellt. Das System wird

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Evidence for a Constitutive Cutinase in Ungerminated Conidia of Erysiphe necator Schwein

Journal of Cytology & Histology, 2013

ABSTRACT Soluble proteins of ungerminated conidia of Erysiphe necator exhibited esterase and cuti... more ABSTRACT Soluble proteins of ungerminated conidia of Erysiphe necator exhibited esterase and cutinase activities, and such hydrolytic activities were measured in the parietal protein fraction. However, histochemical localisation of esterase activity was detected upon further fungal development, as well in elongating germ tubes and in appressoria. The esterase activity was spectrophotometrically quantified using para-nitrophenylbutyrate as a substrate, and cutinase activity was determined using 3H-labelled cutin. Histochemical localisation was determined using indoxyl acetate as a substrate. Diisopropyl fluorophosphate was used as inhibitor of serine hydrolase. The role of a putative constitutive parietal cutinase in the ungerminated conidia of E. necator in adhesion to the host and differentiation of infective structures, as well as implications for successful penetration, are discussed.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Role of stilbenes in the resistance of grapevine to powdery mildew

ABSTRACT

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Effect of fertilisation timing on the partitioning of foliar-applied nitrogen in V itis vinifera cv. Chasselas: a 15 N labelling approach

Australian Journal of Grape and Wine Research, 2015

ABSTRACT Background and AimsYeast assimilable nitrogen (YAN) in grape must is an important determ... more ABSTRACT Background and AimsYeast assimilable nitrogen (YAN) in grape must is an important determinant of wine composition. The effect of foliar nitrogen fertilisation on YAN concentration in must of Vitis vinifera L. cv. Chasselas was studied. Nitrogen assimilation and translocation were investigated by applying 15N-labelled urea at flowering and at veraison.Methods and ResultsFoliar urea was applied on field-grown Chasselas grapevines using labelled (10 atom% 15N) and unlabelled urea. The vines were excavated at harvest, and plant parts were separated and analysed. Thus, the distribution of dry organic matter and of total organic carbon and total organic nitrogen in the plant at harvest was determined. Bunches were the strongest N sink among all of the organs during both fertilisation periods. The highest YAN in the must, however, was obtained when the urea was applied during veraison.Conclusions Isotope labelling was used to describe N partitioning throughout the vine in response to foliar nitrogen fertilisation with urea at flowering and at veraison. Differences between organs in carbon and nitrogen isotope discrimination at natural abundance were established. Fertilisation with urea during veraison increased the YAN concentration in Chasselas grape must.Significance of the StudyResults show that it is more effective to correct YAN deficiency in the vineyard with application of foliar urea during veraison than during flowering.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Induction of defence mechanisms in grapevine leaves by emodin- and anthraquinone-rich plant extracts and their conferred resistance to downy mildew

Plant Physiology and Biochemistry, 2009

The ability of two plant extracts, Rheum palmatum root extract (RPRE) and Frangula alnus bark ext... more The ability of two plant extracts, Rheum palmatum root extract (RPRE) and Frangula alnus bark extract (FABE), to protect Vitis vinifera leaves from Plasmopara viticola infection was evaluated. These natural products are toxic to the pathogen and induce defence reactions in a susceptible cultivar of V. vinifera (V. vinifera cv. Chasselas), including stilbenic phytoalexin accumulation, enhanced peroxidase (EC 1.11.1.7) activity, and a hypersensitive reaction. Inhibition of the first stage of biotrophic hyphal development of P. Viticola by the two plant extracts was observed. HPLC-DAD-MS analysis showed that these two natural extracts contain many phenolic compounds belonging to the anthraquinone family, such as rhein, frangulin A, emodin, aloe-emodin, chrysophanol, and physcion. Emodin alone is able to impair P. viticola development and to stimulate viniferins and the accumulation of pterostilbene.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Susceptibility to downy mildew in grape clusters: New microscopical and biochemical insights

Plant Physiology and Biochemistry, 2012

Grape clusters of different Vitis genotypes, including Vitis vinifera cvs Chasselas and Merlot, a... more Grape clusters of different Vitis genotypes, including Vitis vinifera cvs Chasselas and Merlot, and two interspecific grape varieties, Solaris (cvs. Merzling* x (Saperavi severneyi x Muscat ottonel)) and 2091 (cvs. Gamaret x Bronner), are susceptible or resistant to downy mildew. These cultivars were inoculated with Plasmopara viticola at three developmental stages (BBCH stages 53, 69 and 75). Samples were examined by scanning electron microscopy and the synthesis of stilbenes was measured. Microscopical examinations of pedicels, rachis and calyptras showed important differences in stomatal structures within seasonal development. At BBCH 53, successful infections were observed on all tested cultivars and functional stomata were present, while no infections were observed after this stage. At BBCH 69 and 75, cracks were observed around the stomata and guard cells were unstructured or completely collapsed, leading to closed-like stomata. At BBCH 53, significant stilbene accumulation was quantified in 2091 and Solaris; pterostilbene and δ-viniferin were produced in large amounts. In the susceptible varieties, only piceid and resveratrol were induced. At the other two stages, the concentration of all measured stilbenes was undetectable. The critical roles of seasonal development and stilbenes in the resistance of grape clusters towards downy mildew are discussed.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Stilbenes: Biomarkers of Grapevine Resistance to Disease of High Relevance for Agronomy, Oenology and Human Health

Plant Defence: Biological Control, 2011

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Characterization of 3 new partial stilbene synthase genes out of over 20 expressed in Vitis vinifera during the interaction with Plasmopara viticola

Physiological and Molecular Plant Pathology - PHYSIOL MOLEC PLANT PATHOL, 2005

RT-PCR was used to amplify stilbene synthase (STS) transcripts expressed in the grape–downy milde... more RT-PCR was used to amplify stilbene synthase (STS) transcripts expressed in the grape–downy mildew interaction. Four grape cultivars, Chasselas, IRAC-2029, IRAC-1999 and Solaris (from susceptible to resistant), were used in order to access members of the gene family and some allelic variations. Plant resistance to Plasmopara viticola was scored by quantification of stilbenes 2 days post inoculation and of sporangia at 7 days. RT-PCR products were analyzed by gel electrophoresis, cloned and 300 individual clones were sequenced. Sequences covered 1/3 (455 bp) of the coding region and up to 300 bp of the 3′ untranslated region. A cluster tree of the aligned sequences exhibits 17 main branches, most of which split again suggesting allelic variations. Quantitative real-time PCR was then performed to identify single copy genes coding for STS as well as for the closely related chalcone synthase (CHS). The analysis identified that grapes have two CHS, one CHS-like and close to 25 STS single copy genes. A comparison between a sensitive and a resistant grape to P. viticola is discussed in relation to the stilbene synthase gene family and the problematic to quantify their expression.

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A comprehensive metabolomic study of wine from the Vaud Switzerland vineyard

Planta Medica, 2012

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Protease inhibitors decrease the resistance of Vitaceae to Plasmopara viticola

Plant Physiology and Biochemistry, 2012

Plasmopara viticola must successfully infect susceptible grapevine cultivars to complete its biol... more Plasmopara viticola must successfully infect susceptible grapevine cultivars to complete its biological cycle. In resistant grapevine varieties, P. viticola is blocked by the activation of defense mechanisms; these defense mechanisms produce hypersensitive reactions, which are related to programmed cell death. In animals, programmed cell death is dependent on caspase activities. In plants, different caspase-like proteases assume the same functions. To examine the roles of caspase-like proteases in P. viticola-grapevine interactions, three varieties of grapevine with different levels of P. viticola resistance were chosen. These grapevine varieties were treated with either PMSF, a serine protease inhibitor, or E-64, a cysteine protease inhibitor. The development of the pathogen was followed microscopically, and the plant defense reactions were estimated through stilbene quantification. Both protease inhibitor treatments increased the infection rate in the resistant and immune varieties, diminished the production of toxic stilbenes and changed the level of the plants' susceptibility to the pathogen. In particular, after either protease treatment, the cultivar that was originally immune became resistant (hyphae and haustoria were observed), the resistant cultivar reached the level of a susceptible cultivar (sporulation was observed) and the susceptible cultivar became more sensitive (P. viticola colonized the entirety of the leaf mesophyll).

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Histological study of the responses of two Vitis vinifera cultivars (resistant and susceptible) to Plasmopara viticola infections

Plant Physiology and Biochemistry, 2003

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The effectiveness of stilbenes in resistant Vitaceae: Ultrastructural and biochemical events during Plasmopara viticola infection process

Plant Physiology and Biochemistry, 2011

Bookmarks Related papers MentionsView impact