RNAi of a Putative Grapevine Susceptibility Gene as a Possible Downy Mildew Control Strategy

Downy mildew, caused by the oomycete Plasmopara viticola, is one of the diseases causing the most severe economic losses to grapevine (Vitis vinifera) production. To date, the application of fungicides is the most efficient method to control the pathogen and the implementation of novel and sustainable disease control methods is a major challenge. RNA interference (RNAi) represents a novel biotechnological tool with a great potential for controlling fungal pathogens. Recently, a candidate susceptibility gene (VviLBDIf7) to downy mildew has been identified in V. vinifera. In this work, the efficacy of RNAi triggered by exogenous double-stranded RNA (dsRNA) in controlling P. viticola infections has been assessed in a highly susceptible grapevine cultivar (Pinot noir) by knocking down VviLBDIf7 gene. The effects of dsRNA treatment on this target gene were assessed by evaluating gene expression, disease severity, and development of vegetative and reproductive structures of P. viticola in the leaf tissues. Furthermore, the effects of dsRNA treatment on off-target (EF1α, GAPDH, PEPC, and PEPCK) and jasmonic acid metabolism (COI1) genes have been evaluated. Exogenous application of dsRNA led to significant reductions both in VviLBDIf7 gene expression, 5 days after the treatment, and in the disease severity when artificial inoculation was carried out 7 days after dsRNA treatments. The pathogen showed clear alterations to both vegetative (hyphae and haustoria) and reproductive structures (sporangiophores) that resulted in stunted growth and reduced sporulation. Treatment with dsRNA showed signatures of systemic activity and no deleterious off-target effects. These results demonstrated the potential of RNAi for silencing susceptibility factors in grapevine as a sustainable strategy for pathogen control, underlying the possibility to adopt this promising biotechnological tool in disease management strategies.

Download Full-text

Abalone Viral Ganglioneuritis

Pathogens ◽

10.3390/pathogens9090720 ◽

2020 ◽

Vol 9 (9) ◽

pp. 720

Author(s):

Serge Corbeil

Keyword(s):

Gene Expression ◽

Diagnostic Tests ◽

Management Strategies ◽

Molecular Diagnostic ◽

Economic Losses ◽

Future Research ◽

Abalone Species ◽

Significant Research ◽

Research Findings ◽

Herpesvirus 1

Abalone viral ganglioneuritis (AVG), caused by Haliotid herpesvirus-1 (HaHV-1; previously called abalone herpesvirus), is a disease that has been responsible for extensive mortalities in wild and farmed abalone and has caused significant economic losses in Asia and Australia since outbreaks occurred in the early 2000s. Researchers from Taiwan, China, and Australia have conducted numerous studies encompassing HaHV-1 genome sequencing, development of molecular diagnostic tests, and evaluation of the susceptibility of various abalone species to AVG as well as studies of gene expression in abalone upon virus infection. This review presents a timeline of the most significant research findings on AVG and HaHV-1 as well as potential future research avenues to further understand this disease in order to develop better management strategies.

Download Full-text

Potential of genetic resistance of new table grape hybrids to fungal pathogens

BIO Web of Conferences ◽

10.1051/bioconf/20213402001 ◽

2021 ◽

Vol 34 ◽

pp. 02001

Author(s):

Elena Ilnitskaya ◽

Marina Makarkina ◽

Valeriy Petrov

Keyword(s):

Powdery Mildew ◽

Downy Mildew ◽

Resistance Genes ◽

Dna Markers ◽

Fungal Pathogens ◽

Genetic Resistance ◽

Plasmopara Viticola ◽

Table Grape ◽

Table Grapes ◽

Hybrid Forms

Downy mildew (Plasmopara viticola) and powdery mildew (Erysiphe necator) are the most common and economically significant fungal diseases in vineyards. The task of this work is to study the genotypes of new promising hybrid forms of table grapes for the presence of resistance genes to downy mildew (Rpv10 and Rpv3) and powdery mildew (Ren9) using DNA-markers. The study was carried out on table grape hybrids under the working names Agat dubovskiy, Akelo, Arabella, Artek, Dubovskiy rozovyi, Gamlet, Ispolin, Kishmish dubovskiy, Kurazh, Pestryi, Valensiya and registered variety Liviya. The studied genes were analyzed using markers UDV305 and UDV737 (Rpv3), GF09-46 (Rpv10), CenGen6 (Ren9). The following cultivars were used as reference genotypes: Saperavi severnyi (carries Rpv10 gene) and Regent (Rpv3 and Ren9). It was established that Rpv3 gene is carried by hybrids Kishmish dubovskiy, Agat dubovskiy, Kurazh, Valensiya, Akelo, Gamlet, Dubovskiy rozovyi, Pestryi. Ren9 gene was found in Artek, Agat dubovskiy, Kurazh, Ispolin, Valensiya, Arabella, Gamlet, Dubovskiy rozovyi, Pestryi. The Rpv10 gene was not detected in any of the analyzed grapevine samples. genotypes Agat dubovskiy, Kurazh, Gamlet, Dubovskiy rozovyi, Pestryi, Valensiya carry Rpv3 and Ren9 genes simultaneously. These grapevines have an elegant bunch and large berries that are attractive to consumers.

Download Full-text

Detection and Characterization of Carboxylic Acid Amide-Resistant Plasmopara viticola in China Using a TaqMan-MGB Real-Time PCR

Plant Disease ◽

10.1094/pdis-02-20-0291-re ◽

2020 ◽

Vol 104 (9) ◽

pp. 2338-2345

Author(s):

Xiaoqing Huang ◽

Xina Wang ◽

Fanfang Kong ◽

Theo van der Lee ◽

Zhongyue Wang ◽

...

Keyword(s):

Carboxylic Acid ◽

Real Time ◽

Downy Mildew ◽

Real Time Pcr ◽

Fungicide Resistance ◽

Management Strategies ◽

Acid Amide ◽

Plasmopara Viticola ◽

Carboxylic Acid Amide ◽

Caa Fungicides

Grape production is increasing globally and so are problems with downy mildew, one of the main constraints in grape production. Downy mildew on grape is caused by Plasmopara viticola, an obligate biotrophic pathogen belonging to the oomycetes. Control of the disease is usually performed by fungicide applications, of which carboxylic acid amide (CAA) fungicides represent one of the most widely used groups of fungicides. Our previous research showed that the extensive application of CAA fungicides can result in fungicide resistance and in China, CAA-resistant isolates of P. viticola were collected from the field in 2014. To monitor the distribution and spread of CAA fungicide resistance, we developed a TaqMan-minor groove binder (MGB) real-time PCR-based method designed on a functional mutation in the PvCesA3 gene that allows efficient identification of CAA fungicide resistant and sensitive genotypes. The assay was validated on 50 isolates using Sanger sequencing and fungicide bioassays and exploited in a comprehensive survey comprising 2,227 single-sporangiophore isolates from eight major grapevine regions in China. We demonstrate that CAA fungicide resistance in P. viticola is widespread in China. On average, 53.3% of the isolates were found to be resistant, but marked differences were found between locations with percentages of resistant isolates varying from 0.3 to 96.6%. Furthermore, the frequency of CAA-resistant isolates was found to be significantly correlated with the exposure to CAA fungicides (P < 0.05). We further discussed the possibilities to apply the TaqMan-MGB real-time PCR assay to assess the frequency of fungicide-resistant P. viticola isolates in each region or vineyard, which would facilitate the correct choice of fungicide for grape downy mildew and resistance management strategies.

Download Full-text

Susceptibility of Cold-Climate Wine Grape Cultivars to Downy Mildew, Powdery Mildew, and Black Rot

Plant Disease ◽

10.1094/pdis-01-17-0022-re ◽

2017 ◽

Vol 101 (7) ◽

pp. 1077-1085 ◽

Cited By ~ 3

Author(s):

David S. Jones ◽

Patricia S. McManus

Keyword(s):

Powdery Mildew ◽

Downy Mildew ◽

Management Strategies ◽

Plasmopara Viticola ◽

Cold Climate ◽

Black Rot ◽

Wine Grape ◽

Plant Host ◽

Northern United States ◽

Grape Cultivars

Lack of knowledge regarding the susceptibility of cold-climate hybrid wine grape cultivars may be leading to the overuse of fungicides and underutilization of plant host resistance to combat disease in the northern United States. To provide new insights on diseases of cold-climate cultivars and to update management recommendations, disease was evaluated in three vineyards containing eight cultivars that were not sprayed with fungicides in 2015 and 2016. Disease severity or incidence of downy mildew (Plasmopara viticola), powdery mildew (Erysiphe necator), and black rot (Guignardia bidwellii) were measured from bud break until 2 weeks after harvest. Cold-climate cultivars ranged widely in susceptibility to different diseases and, although several cultivars were relatively resistant to two diseases, no cultivar was highly resistant to all three diseases. Additionally, a difference between foliar and fruit susceptibility for all three diseases was noted in several cultivars. These data provide a foundation for developing low-spray and certified organic disease management strategies for cold-climate wine grape cultivars based on susceptibility to disease.

Download Full-text

Single berry sampling reveals novel insights into transcriptomic changes induced by leafroll virus infections in grapevine (V. vinifera)

10.21203/rs.2.22668/v1 ◽

2020 ◽

Author(s):

Sana Ghaffari ◽

Jean Sébastien Reynard ◽

Markus Rienth

Keyword(s):

Gene Expression ◽

Defense Mechanism ◽

Sugar Content ◽

Pinot Noir ◽

Wine Industry ◽

Economic Losses ◽

Ripening Stage ◽

Sampling Protocols ◽

Molecular Studies ◽

Phenological Shifts

Abstract Background Grapevine leafroll associated viruses (GLRaV), the causing agents of grapevine leafroll disease (GLD) are amongst the most devastating graft and vector transmitted pathogens in viticulture and responsible for important economic losses in the wine industry. Reported fruit alterations caused by GLD consist in a delay of ripening, a reduction in anthocyanins, aroma compounds and sugar concentration. The molecular interactions underlying the quality deteriorating effects are not well understood so far. The few conducted molecular studies on infected berries did associate the lack of anthocyanin and sugar content with a repression of key genes of the respective pathways. However, sampling protocols in such studies never accounted for berry heterogeneity and potential virus induced phenological shifts. Thus, such commonly used sampling strategies could have introduced unquantifiable biases in gene expression studies which would impede the discovery of novel molecular information. The aim of the present study was to investigate the effects of GLRaV-1 and GLRaV-1&3 infections on berry physiology of Pinot Noir vines. Berries of different treatments were individually sampled and analyzed for sugar and organic acids. According to this biochemical analysis 2 homogenous stages were reconstituted to circumvent berry heterogeneity and compensate for virus induced phenological shifts. RNA of 18 reconstituted samples (2 stages and 3 treatments) was extracted, sequenced and analyzed for differentially expressed genes (DEGs). Results A total of 2136 transcripts were modulated by GLRaV-1 and GLRaV-1&3 infections. Interestingly the transcriptome of the early ripening berry was much more affected as the later ripening stage. Several pathways related to abiotic and biotic stress, defense mechanism as well as plant immunity showed a virus-induced upregulation in dependence to ripening stage and infection severity. Surprisingly, the previously reported repression of anthocyanin biosynthesis and sugar metabolism could not be confirmed by gene expression. This illustrates that the main damaging effect on GLRaV infection is rather related to a phenological shift than to a direct impact on metabolism. Conclusions The here reported results give new insight in the mechanism of leafroll infection and emphasize the importance of the sampling protocol of molecular studies investigating berry metabolism.

Download Full-text

Identification and Characterization of Fungal Pathogens Causing Fruit Rot of Deciduous Holly

Plant Disease ◽

10.1094/pdis-02-18-0372-re ◽

2018 ◽

Vol 102 (12) ◽

pp. 2430-2445 ◽

Cited By ~ 4

Author(s):

Shan Lin ◽

Nancy J. Taylor ◽

Francesca Peduto Hand

Keyword(s):

Fungal Pathogens ◽

Disease Incidence ◽

Phylogenetic Analyses ◽

Management Strategies ◽

Morphological Characterization ◽

Fruit Rot ◽

Economic Losses ◽

Yield Reduction ◽

Inoculum Concentration ◽

Fruit Samples

Cut branches of deciduous holly (Ilex spp. L.) harboring colorful berries are traditionally used as ornaments in holiday decorations. Since 2012, a fruit rot of unspecified cause has resulted in significant yield reduction and economic losses across Midwestern and Eastern U.S. nurseries. In this study, symptomatic fruit samples collected from nine different locations over five years were analyzed, and several fungal species were isolated. A combination of morphological characterization, multilocus phylogenetic analyses, and pathogenicity assays revealed that Alternaria alternata and Diaporthe ilicicola sp. nov. were the primary pathogens associated with symptomatic fruit. Other fungi including A. arborescens, Colletotrichum fioriniae, C. nymphaeae, Epicoccum nigrum, and species in the D. eres species complex appeared to be minor pathogens in this disease complex. In detached fruit pathogenicity assays testing the role of wounding and inoculum concentration on disease development, disease incidence and severity increased when fruit was wounded and inoculated with a higher inoculum concentration. These findings indicate that management strategies that can protect fruit from injury or reduce inoculum may lower disease levels in the field. This research established the basis for further studies on this emerging disease and the design of research-based management strategies. To our knowledge, it also represents the first report of species of Alternaria, Colletotrichum, Diaporthe, and Epicoccum causing fruit rot of deciduous holly.

Download Full-text

Novel Aspects on The Interaction Between Grapevine and Plasmopara viticola: Dual-RNA-Seq Analysis Highlights Gene Expression Dynamics in The Pathogen and The Plant During The Battle For Infection

Genes ◽

10.3390/genes11030261 ◽

2020 ◽

Vol 11 (3) ◽

pp. 261 ◽

Cited By ~ 1

Author(s):

Silvia Laura Toffolatti ◽

Gabriella De Lorenzis ◽

Matteo Brilli ◽

Mirko Moser ◽

Vahid Shariati ◽

...

Keyword(s):

De Novo ◽

Susceptibility Gene ◽

Plasmopara Viticola ◽

Pinot Noir ◽

Gene Encoding ◽

Grapevine Cultivar ◽

Gene Expression Dynamics ◽

Plant Pathogen Interaction ◽

First Time ◽

Encoding Genes

Mgaloblishvili, a Vitis vinifera cultivar, exhibits unique resistance traits against Plasmopara viticola, the downy mildew agent. This offers the unique opportunity of exploring the molecular responses in compatible and incompatible plant-pathogen interaction. In this study, whole transcriptomes of Mgaloblishvili, Pinot noir (a V. vinifera susceptible cultivar), and Bianca (a resistant hybrid) leaves, inoculated and non-inoculated with the pathogen, were used to identify P. viticola effector-encoding genes and plant susceptibility/resistance genes. Multiple effector-encoding genes were identified in P. viticola transcriptome, with remarkable expression differences in relation to the inoculated grapevine cultivar. Intriguingly, five apoplastic effectors specifically associated with resistance in V. vinifera. Gene coexpression network analysis identified specific modules and metabolic changes occurring during infection in the three grapevine cultivars. Analysis of these data allowed, for the first time, the detection in V. vinifera of a putative P. viticola susceptibility gene, encoding a LOB domain-containing protein. Finally, the de novo assembly of Mgaloblishvili, Pinot noir, and Bianca transcriptomes and their comparison highlighted novel candidate genes that might be at the basis of the resistant phenotype. These results open the way to functional analysis studies and to new perspectives in molecular breeding of grapevine for resistance to P. viticola.

Download Full-text

Downy Mildew from Lake Erie Vineyards is Diverse for the G143A SNP Conferring Resistance to Quinone Outside Inhibitor Fungicides

Plant Health Progress ◽

10.1094/php-2013-0422-01-rs ◽

2013 ◽

Vol 14 (1) ◽

pp. 23

Author(s):

Christopher T. Gee ◽

Stephanie Chestnut ◽

Eilene Duberow ◽

Andrea Collins ◽

Michael A. Shields

Keyword(s):

Downy Mildew ◽

Fungal Pathogens ◽

Lake Erie ◽

Single Mode ◽

Plasmopara Viticola ◽

Qoi Fungicides ◽

Quinone Outside Inhibitor ◽

Development Of Resistance ◽

Qualitative Level ◽

Qoi Resistance

Downy mildew (Plasmopara viticola) is a significant problem in grape vineyards throughout the growing season. Control of downy mildew is carried out with a combination of host tolerance and chemical applications. Even in vineyards planted with very tolerant varieties (e.g., Concord), control is important in years with ideal pathogen conditions. Fungicides with a single mode of action possess a very high potential for the development of resistance. Resistance has been observed often in the Quinone outside inhibitor (QoI) fungicides, such as strobilurins. We ascertained the levels of QoI resistance in downy mildew colonies on diseased leaves using CAPS-PCR to detect the glycine to alanine mutation (G143A) known to confer a qualitative level of resistance in fungal pathogens. Our data uncovered a small percentage of samples that contain G143A, suggesting an overall low level of QoI resistance. The low prevalence of the resistant single nucleotide polymorphism (SNP) suggests that QoI fungicides should remain a viable control mechanism in Lake Erie vineyards. Additionally, it appears that a viticultural region where tolerant hosts predominant and QoI use is minimal, resistance buildup in the pathogen population will be minimal. Accepted for publication 15 January 2013. Published 22 April 2013.

Download Full-text

High night temperature promotes downy mildew in grapevine via attenuating plant defence response and enhancing early Plasmopara viticola infection

Plant Protection Science ◽

10.17221/92/2020-pps ◽

2020 ◽

Vol 57 (No. 1) ◽

pp. 21-30

Author(s):

Yoshinao Aoki ◽

Arisa Usujima ◽

Shunji Suzuki

Keyword(s):

Downy Mildew ◽

Cultured Cells ◽

Management Strategies ◽

Plant Defence ◽

Plasmopara Viticola ◽

Grape Berry ◽

Night Temperature ◽

Factors Affecting ◽

Temperature Conditions ◽

Berry Quality

The night temperature is one of the critical environmental factors affecting the grape berry quality. The objective of this study was to clarify whether a high night temperature promotes downy mildew on grapevines. The high night temperature conditions suppressed the gene expression of the pathogenesis-related proteins in the grapevine cultured cells and grapevine seedlings compared with the control night temperature conditions. The Plasmopara viticola colony formation on the leaves of the seedlings exposed to the control night temperature conditions became slightly noticeable on day 5 after inoculation, whereas a large number of colonies were clearly observed on the leaves of the seedlings exposed to the high night temperature conditions. On day 10 after inoculation, the leaf defoliation and withering were marked in the P. viticola infected seedlings exposed to the high night temperature conditions. The high night temperature conditions promoted the P. viticola zoospore germination. These results suggest that the high night temperature promoted the grape downy mildew by attenuating the constitutive plant defence response as well as enhancing the P. viticola early infection. Viticulturists should be vigilant regarding pest management strategies against the P. viticola primary infection of grapevines when high night temperatures continue for a long time.

Download Full-text

Solar radiation affects grapevine susceptibility to Plasmopara Viticola

Scientia Agricola ◽

10.1590/s0103-90162008000700011 ◽

2008 ◽

Vol 65 (spe) ◽

pp. 65-70 ◽

Cited By ~ 4

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.

Download Full-text