Optically-assessed preformed flavonoids and susceptibility of grapevine to Plasmopara viticola under different light regimes

2008 ◽  
Vol 35 (1) ◽  
pp. 77 ◽  
Author(s):  
Giovanni Agati ◽  
Zoran G. Cerovic ◽  
Anna Dalla Marta ◽  
Valentina Di Stefano ◽  
Patrizia Pinelli ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Large Scale ◽  
Plasmopara Viticola ◽  
Vitis Vinifera L ◽  
Infected Leaf ◽  
Light Regimes ◽  
Polyphenolic Content ◽  
Non Destructive ◽  
Large Scale Screening

The role of flavonoids in the response of plants to Plasmopara viticola, the phytopathogen agent of downy mildew, was studied in the Vitis vinifera L. cultivar Sangiovese. Grapevines in the vineyard were exposed to two light regimes, 100% and 35% of full sunlight in order to induce differences in total leaf polyphenolic content. Epidermal leaf phenolic compounds were assessed optically, using the Dualex chlorophyll fluorescence-based portable leaf-clip. Dualex data were calibrated by means of HPLC analysis of extracts from the same measured leaves. Good correlations were obtained with total flavonoid contents, which consist mainly of quercetin 3-O-glucuronide. From the Dualex non-destructive measurements, we showed that full-sun exposed leaves contained 75% more flavonoids than shaded leaves. Inoculation of leaves with P. viticola sporangia resulted in a significantly lower infected leaf area in sun-lit leaves compared with shaded ones, as seen from subsequent analysis of the downy mildew severity. These results indicated an inverse relationship between preformed flavonoids and the susceptibility of grapevines to downy mildew. The rapid optical method for the non-destructive assessment of flavonoids presented here could be useful for large scale screening and predicting V. vinifera susceptibility to P. viticola.

scholarly journals The Grapevine E3 Ubiquitin Ligase VriATL156 Confers Resistance against the Downy Mildew Pathogen Plasmopara viticola

2021 ◽  
Vol 22 (2) ◽  
pp. 940
Author(s):  
Elodie Vandelle ◽  
Pietro Ariani ◽  
Alice Regaiolo ◽  
Davide Danzi ◽  
Arianna Lovato ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Ubiquitin Ligase ◽  
Control Measure ◽  
Durable Resistance ◽  
Genetic Resistance ◽  
E3 Ubiquitin Ligase ◽  
Plasmopara Viticola ◽  
Vitis Vinifera L ◽  
Vitis Species ◽  
Vitis Riparia

Downy mildew, caused by Plasmopara viticola, is one of the most severe diseases of grapevine (Vitis vinifera L.). Genetic resistance is an effective and sustainable control strategy, but major resistance genes (encoding receptors for specific pathogen effectors) introgressed from wild Vitis species, although effective, may be non-durable because the pathogen can evolve to avoid specific recognition. Previous transcriptomic studies in the resistant species Vitis riparia highlighted the activation of signal transduction components during infection. The transfer of such components to V. vinifera might confer less specific and therefore more durable resistance. Here, we describe the generation of transgenic V. vinifera lines constitutively expressing the V. riparia E3 ubiquitin ligase gene VriATL156. Phenotypic and molecular analysis revealed that the transgenic plants were less susceptible to P. viticola than vector-only controls, confirming the role of this E3 ubiquitin ligase in the innate immune response. Two independent transgenic lines were selected for detailed analysis of the resistance phenotype by RNA-Seq and microscopy, revealing the profound reprogramming of transcription to achieve resistance that operates from the earliest stages of pathogen infection. The introduction of VriATL156 into elite grapevine cultivars could therefore provide an effective and sustainable control measure against downy mildew.

scholarly journals Geographic Distribution of Cryptic Species of Plasmopara viticola Causing Downy Mildew on Wild and Cultivated Grape in Eastern North America

2014 ◽  
Vol 104 (7) ◽  
pp. 692-701 ◽  
Author(s):  
Mélanie Rouxel ◽  
Pere Mestre ◽  
Anton Baudoin ◽  
Odile Carisse ◽  
Laurent Delière ◽  
...  
Keyword(s):  
North America ◽  
Cryptic Species ◽  
Downy Mildew ◽  
Geographic Distribution ◽  
Host Species ◽  
Large Scale ◽  
Plasmopara Viticola ◽  
Eastern North America ◽  
Grape Downy Mildew ◽  
Parthenocissus Quinquefolia

The putative center of origin of Plasmopara viticola, the causal agent of grape downy mildew, is eastern North America, where it has been described on several members of the family Vitaceae (e.g., Vitis spp., Parthenocissus spp., and Ampelopsis spp.). We have completed the first large-scale sampling of P. viticola isolates across a range of wild and cultivated host species distributed throughout the above region. Sequencing results of four partial genes indicated the presence of a new P. viticola species on Vitis vulpina in Virginia, adding to the four cryptic species of P. viticola recently recorded. The phylogenetic analysis also indicated that the P. viticola species found on Parthenocissus quinquefolia in North America is identical to Plasmopara muralis in Europe. The geographic distribution and host range of five pathogen species was determined through analysis of the internal transcribed spacer polymorphism of 896 isolates of P. viticola. Among three P. viticola species found on cultivated grape, one was restricted to Vitis interspecific hybrids within the northern part of eastern North America. A second species was recovered from V. vinifera and V. labrusca, and was distributed across most of the sampled region. A third species, although less abundant, was distributed across a larger geographical range, including the southern part of eastern North America. P. viticola clade aestivalis predominated (83% of isolates) in vineyards of the European winegrape V. vinifera within the sampled area, indicating that a single pathogen species may represent the primary threat to the European host species within eastern North America.

scholarly journals Effect of Detergent on the Quantification of Grapevine Downy Mildew Sporangia from Leaf Discs

HortScience ◽  
2015 ◽  
Vol 50 (5) ◽  
pp. 656-660 ◽  
Author(s):  
Atsushi Kono ◽  
Akihiko Sato ◽  
Bruce Reisch ◽  
Lance Cadle-Davidson
Keyword(s):  
Downy Mildew ◽  
Leaf Disc ◽  
Plasmopara Viticola ◽  
Inhibitory Effect ◽  
Tween 20 ◽  
Infected Leaf ◽  
Grapevine Downy Mildew ◽  
Visual Rating ◽  
Leaf Discs ◽  
Highly Correlated

Grapevine downy mildew (DM), caused by the oomycete Plasmopara viticola (Berk. & Curt.) Berlese & de Toni, is a major disease, especially in humid viticultural areas. Development of resistant cultivars is an important objective for grapevine breeding. To establish a reliable and inexpensive quantitative method to aid in breeding for DM resistance, we improved the method for counting the number of sporangia on leaf discs, and developed a method for counting the number of sporangia in solution. To prevent the loss of DM sporangia from adhesion onto plastic ware, we found as little as 0.01% Tween 20 was effective. On the other hand, this detergent was shown to have a severe inhibitory effect upon DM infection of leaves. We developed a sporangia counting method using dried droplets of DM suspensions, and the method was highly correlated with counting by hemacytometer (R2 > 0.96). The nonparametric Spearman’s rank correlations between visual rating and the number of the sporangia were as high as ρ = 0.82 to 0.91, suggesting that evaluation by the visual rating could provide a good estimate of the sporangia numbers on leaf discs. We established a high-throughput and inexpensive method with acceptable accuracy for DM resistance evaluation based on a leaf disc assay, and our results suggested that visual ratings of infected leaf discs provide a good estimate of sporangia numbers.

Large-Scale Screening and Identification of Novel Pathogenic Staphylococcus aureus Genes Using a Silkworm Infection Model

2020 ◽  
Vol 221 (11) ◽  
pp. 1795-1804 ◽  
Author(s):  
Atmika Paudel ◽  
Hiroshi Hamamoto ◽  
Suresh Panthee ◽  
Yasuhiko Matsumoto ◽  
Kazuhisa Sekimizu
Keyword(s):  
Staphylococcus Aureus ◽  
Large Scale ◽  
Opportunistic Pathogen ◽  
Infection Model ◽  
Colony Forming Units ◽  
Screening And Identification ◽  
Transposon Mutants ◽  
Pathogenicity Tests ◽  
Large Scale Screening

Abstract The regulatory network of virulence factors produced by the opportunistic pathogen Staphylococcus aureus is unclear and the functions of many uncharacterized genes in its genome remain to be elucidated. In this study, we screened 380 genes whose function was unassigned, utilizing gene-disrupted transposon mutants of the community-acquired methicillin-resistant S. aureus USA300 for pathogenicity in silkworms. We identified 10 strains with reduced silkworm killing ability. Among them, 8 displayed reduced virulence in a mouse model as evidenced by reduced colony-forming units in organs of infected mice. The role of each gene in pathogenicity was further confirmed by complementation and pathogenicity tests in silkworms, where we found that the phenotype was not restored in 1 strain. Additionally, some of the mutants displayed reduced hemolysis, proteolysis, pigment production, and survival in murine RAW 264.7 monocyte-macrophage cells. These newly identified genes involved in virulence will enhance our understanding of the pathogenicity of S. aureus.

scholarly journals Absence of Oospores of Downy Mildew of Grape Caused by Plasmopara viticola as the Source of Primary Inoculum in Most Western Australian Vineyards

Plant Disease ◽  
2005 ◽  
Vol 89 (7) ◽  
pp. 777-777 ◽  
Author(s):  
B. X. Killigrew ◽  
K. Sivasithamparam ◽  
E. S. Scott
Keyword(s):  
Downy Mildew ◽  
Secondary Infection ◽  
Plasmopara Viticola ◽  
The State ◽  
Annual Rainfall ◽  
Infected Leaf ◽  
Wine Grape ◽  
Primary Inoculum ◽  
The North ◽  
Plant Pathol

Grapevine downy mildew, caused by the obligate, oomycete pathogen, Plasmopara viticola, was first recorded in Western Australia (W.A.) in 1998 (2) and has subsequently been observed in most viticultural regions of the state. Heterothallism in P. viticola was established by Wong et al. (3), whereby more than one mating type of the pathogen is required for sexual reproduction to occur. Oospores are considered to be the source of primary inoculum for this disease with further, secondary infection being advanced by asexual inoculum. However, recent research in European vineyards suggests that the majority of infection throughout the growing season arises via sexually derived (oosporic) inoculum (1). Since downy mildew is relatively new to W.A., few surveys have been conducted to study populations of the pathogen within the state. It is also noteworthy that the incidence of oospores in Australian vineyards has not been reported. The objective of this research was to assess the occurrence and type of inoculum of P. viticola in W.A. vineyards. A total of 1,266 P. viticola-infected leaf discs (LD) from eight wine-grape (775 LD), five table-grape (450 LD), and seven unknown (41 LD) cultivars grown in 16 vineyards in 10 geographically separate regions of W.A. were collected in the growing seasons of 2001-2003. These regions range from Chittering in the north to Albany in the south and received 700 to 1,200 mm annual rainfall, mostly in winter. Each LD was cleared in 1 M KOH at 60°C for 12 to 24 h and then was assessed for the presence of oospores with light microscopy. Leaves showing “mosaic”-type lesions (older infection) late in the season were collected where possible to ensure colony maturity and an increased likelihood of oospore formation. All LD from all regions were negative for the presence of oospores except for samples from a single vineyard (approximately 1,200 mm annual rainfall), where all 140 LD from six wine-grape cultivars contained oospores. The discovery that oospores were present in only one of 16 sampled vineyards provides a rare opportunity to study gene flow in field populations of the pathogen with time and to determine sources of primary inoculum where overwintering of P. viticola may not involve oospores. References: (1) S. McKirdy et al. Plant Dis. 83:301, 1999. (2) A. Rumbou et al. Eur. J. Plant Pathol. 110:379, 2004. (3) F. P. Wong et al. Plant Pathol. 50:427, 2001.

UV screening by phenolics in berries of grapevine (Vitis vinifera)

2003 ◽  
Vol 30 (12) ◽  
pp. 1177 ◽  
Author(s):  
Christiane A. Kolb ◽  
Jiri Kopecký ◽  
Markus Riederer ◽  
Erhard E. Pfündel
Keyword(s):  
Vitis Vinifera ◽  
High Performance ◽  
Solar Spectrum ◽  
Outdoor Exposure ◽  
Hydroxycinnamic Acids ◽  
Vitis Vinifera L ◽  
Visible Radiation ◽  
Natural Radiation ◽  
Light Regimes

The role of phenolics in UV-screening was investigated in berries of a white grape cultivar (Vitis vinifera L. cv. Bacchus). Fluorescence microscopy revealed accumulation of phenolics in the skin of berries and, by high performance liquid chromatography and mass spectrometry, flavonols and hydroxycinnamic acids were identified as the main groups of UV-absorbing phenolics. Relationships between natural radiation and the synthesis of phenolics were studied in plants that were cultivated in the absence of UV radiation in a greenhouse before outdoor exposure to three different light regimes: the entire solar spectrum, the solar spectrum minus UV-B radiation and only visible radiation. During six days of exposure, flavonol synthesis was significantly stimulated by natural UV, in particular UV-B, but concentrations of hydroxycinnamic acids decreased under all conditions. Direct comparison of fluorimetrically-determined skin absorbance with absorbance of extracted flavonols or hydroxycinnamic acids suggested that acclimation of UV screening depends almost exclusively on flavonol synthesis. While increased flavonol levels resulted in efficient UV-A shielding, UV-B shielding was incomplete, probably due to decreased levels of the UV-B-absorbing hydroxycinnamic acids during exposure.

scholarly journals A large-scale screening of quinoa accessions reveals an important role of epidermal bladder cells and stomatal patterning in salinity tolerance

2019 ◽  
Vol 168 ◽  
pp. 103885 ◽  
Author(s):  
Ali Kiani-Pouya ◽  
Fatemeh Rasouli ◽  
Nadia Bazihizina ◽  
Heng Zhang ◽  
Rainer Hedrich ◽  
...  
Keyword(s):  
Salinity Tolerance ◽  
Large Scale ◽  
Bladder Cells ◽  
Large Scale Screening ◽  
Stomatal Patterning

scholarly journals Vitis vinifera canes, a source of stilbenoids against downy mildew

OENO One ◽  
2016 ◽  
Vol 50 (3) ◽  
Author(s):  
Tristan Richard ◽  
Assia Abdelli-Belhad ◽  
Xavier Vitrac ◽  
Pierre Waffo-Téguo ◽  
Jean-Michel Mérillon
Keyword(s):  
Vitis Vinifera ◽  
Downy Mildew ◽  
Leaf Surface ◽  
Bordeaux Mixture ◽  
Vitis Vinifera L ◽  
Infected Leaf ◽  
Infection Frequency ◽  
Attack Frequency ◽  
Zoospore Release ◽  
Pathogen Attack

Aim: To investigate the antifungal efficacy of grape cane extracts enriched in stilbenes against Plasmopara viticola by in vivo experiments on grape plants.Methods and results: Experiments on grape plants were carried out from 2007 to 2008 at commercial vineyards in « Le Tourne » (southwest region of France) on Vitis vinifera L. cv Merlot plants and in a greenhouse, where 45-day-old plants (Merlot) were used. Grapevine plants were treated with stilbene extract (STE) or « Bordeaux mixture » (BM) as positive control. STE, prepared from Vitis vinifera canes, contained 33% of total stilbenes ranging from monomers to tetramers and was used at 5 g L-1. The degree of protection against downy mildew was determined as the percentage of infected leaf surface area and pathogen attack frequency. On young plants in greenhouse, P. viticola inoculation and three treatments with STE were carried out. After the treatments, the disease reduction was from 59 to 69% for pathogen attack frequency and from 83 to 88% for infected leaf surface for the two modes of infestation (artificial and secondary). STE triggered a similar intense decrease in downy mildew infection as recorded for BM. In the vineyard assay, downy mildew infection was allowed to occur naturally. Field grown plants were treated every 7th day for eight weeks or every 14th day for eight weeks during June and July. We observed that STE was also able to prevent P. viticola infection in vineyard but to a lesser extent. Treatment with STE every 7th day provided better results in terms of infection frequency and infected leaf area than that every 14th day. STE treatment of plants every 7th day in vineyard reduced the frequency of attack by 16 to 39% and leaf surface infection by 57 to 61%, which was lower than that recorded for BM. STE also displayed in vitro inhibitory effects on the release of zoospores from sporangia and the germination of zoospores of P. viticola. Zoospore germination was completely inhibited at a concentration of 100 mg L-1 and zoospore release was inhibited at 330 mg L-1.Conclusions: Treatment of young grapevine plants in greenhouse with stilbene extract from grapevine canes offered considerable protection against P. viticola that was identical to that provided by Bordeaux mixture. STE was also able to prevent P. viticola infection in vineyard but to a lesser extent. Treatment with STE every 7th day in vineyard provided better results than that every 14th day.Significance and impact of the study: Stilbenes from grapevine canes are good candidates as natural fungicides against downy mildew. Given the very large quantity of grape canes available each year, this strategy could be scaled up to control this grapevine disease in a sustainable manner.

scholarly journals First Report of Grapevine Downy Mildew (Plasmopara viticola) in Commercial Viticulture in Western Australia

Plant Disease ◽  
1999 ◽  
Vol 83 (3) ◽  
pp. 301-301 ◽  
Author(s):  
S. J. McKirdy ◽  
I. T. Riley ◽  
I. J. Cameron ◽  
P. A. Magarey
Keyword(s):  
Downy Mildew ◽  
Western Australia ◽  
Pathogenic Fungi ◽  
First Record ◽  
Plasmopara Viticola ◽  
Weather Data ◽  
Vitis Vinifera L ◽  
Grapevine Downy Mildew ◽  
Code Of Practice ◽  
Rate Of Spread

Despite the suitability of climate, Western Australia was one of the few grape (Vitis vinifera L.) growing areas free of grapevine downy mildew (Plasmopara viticola (Berk. & M. A. Curtis) Berl. & De Toni in Sacc.). Area freedom had been maintained by restricting the movement of host material and machinery from outside the state and fungicide use in Western Australia vineyards had been considerably less. P. viticola was detected in 1997 in 14 of 15 vines growing at Kalumburu, a remote community in the semi-arid tropics of Western Australia, and was eradicated. In October 1998, grape leaves with oilspots typical of downy mildew were received from a grower in the Swan Valley near Perth, one of the main production areas of Western Australia. Sporangia were hyaline and ellipsoid (14 × 11 μm), were borne on treelike sporangiophores, and were consistent with those described for P. viticola (1). This is the first record of P. viticola in commercial viticulture in Western Australia. A response plan for exotic diseases was activated and after 2 weeks of surveillance the disease was found in 45 of 70 vineyards surveyed of the 280 vineyards in the Swan Valley. Given the extent of spread, eradication of downy mildew was not considered possible. Weather data for August to October 1998 indicated the likelihood of several infection periods from budburst to flowering when the disease was first detected. Crop loss will be considerable in many vineyards. P. viticola was also found in bench-grafted cuttings in pots in leaf consigned from the Swan Valley to several other areas in August 1998. Downy mildew was found in other areas only in association with these consigned vines. An industry code of practice, including hygiene, is being developed to slow the rate of spread of P. viticola in Western Australia. Reference: (1) Anon. C.M.I. Descriptions of Pathogenic Fungi and Bacteria No. 980, 1989.

scholarly journals Solar radiation affects grapevine susceptibility to Plasmopara Viticola

2008 ◽  
Vol 65 (spe) ◽  
pp. 65-70 ◽  
Author(s):  
Anna Dalla Marta ◽  
Valentina Di Stefano ◽  
Zoran G. Cerovic ◽  
Giovanni Agati ◽  
Simone Orlandini
Keyword(s):  
Solar Radiation ◽  
Downy Mildew ◽  
Disease Severity ◽  
Inverse Relationship ◽  
Direct Action ◽  
Growing Season ◽  
Plasmopara Viticola ◽  
Polyphenolic Content ◽  
Grapevine Leaves ◽  
Plant Compounds

Solar radiation plays an important role in the development of some fungal diseases due to its direct action on the microorganisms and also its indirect effect on the production of specific plant compounds. This experiment examined the effect of two light environments (100% and 35% of full strength) on the polyphenolic content of grapevine leaves and quantified their relation to resistance to downy mildew (Plasmopara viticola). Leaf epidermal polyphenolic contents were non-destructively measured during the growing season 2006 using the Dualex chlorophyll fluorescence-based portable leaf-clip. The experimental design consisted of six parcels of 30 vines and measurements were performed on the 12 central vines. The leaves were inoculated with a sporangia suspension containing 50,000 sporangia of P. viticola per mL and the disease severity was assessed after the appearance of symptoms. Leaves maintained at 100% sun had high polyphenolic content and significantly lower disease severity compared to leaves under shading nets. These results indicate an inverse relationship between produced polyphenolics and downy mildew severity.

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