Double-Stranded RNA Targeting Dicer-Like Genes Compromises the Pathogenicity of Plasmopara viticola on Grapevine
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ABSTRACT:
SUBMITTER: Haile Z
PROVIDER: S-EPMC8167485 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Downy mildew caused by Plasmopara viticola is one of the most destructive diseases of Vitis vinifera worldwide. Grapevine breeding programs have introgressed P. viticola-resistant traits into cultivated V. vinifera genotypes and launched interspecific hybrids with resistance against downy mildew. In general, pathogen infection affects primary metabolism, reduces plant growth and development and modifies the secondary metabolism toward defense responses, which are costly in terms of carbon production and utilization. The objective of this work was to evaluate the photosynthesis impairment by inducible defenses at the leaf level in V. vinifera cultivars resistant to P. viticola. Photosynthetic limitations imposed by P. viticola in susceptible and resistant grapevine cultivars were evaluated. Histochemical localization of hydrogen peroxide and superoxide and the activity of ascorbate peroxidase were assessed. Measurements of leaf gas exchange, chlorophyll fluorescence and the response of leaf CO2 assimilation to increasing air CO2 concentrations were taken, and photosynthetic limitations determined in cultivars Solaris (resistant) and Riesling (susceptible). The net photosynthetic rates were reduced (-25%) in inoculated Solaris plants even before the appearance of cell death-like hypersensitive reactions ("HR"). One day after "HR" visualization, the net photosynthetic rate of Solaris was reduced by 57% compared with healthy plants. A similar pattern was noticed in resistant Cabernet Blanc and Phoenix plants. While the susceptible cultivars did not show any variation in leaf gas exchange before the appearance of visual symptoms, drastic reductions in net photosynthetic rate and stomatal conductance were found in diseased plants 12 days after inoculation. Decreases in the maximum Rubisco carboxylation rate and photochemical impairment were noticed in Riesling after inoculation with P. viticola, which were not found in Solaris. Damage to the photochemical reactions of photosynthesis was likely associated with the oxidative burst found in resistant cultivars within the first 24 h after inoculation. Both chlorophyll degradation and stomatal closure were also noticed in the incompatible interaction. Taken together, our data clearly revealed that the defense response against P. viticola causes a photosynthetic cost to grapevines, which is not reversible even 12 days after the pathogen infection.
| S-EPMC7098430 | biostudies-literature
Project description:Downy mildew, caused by the biotrophic oomycete Plasmopara viticola, is one of the most serious grapevine diseases. The development of new varieties, showing partial resistance to downy mildew, through traditional breeding provides a sustainable and effective solution for disease management. Marker-assisted-selection (MAS) provide fast and cost-effective genotyping methods, but phenotyping remains necessary to characterize the host-pathogen interaction and assess the effective resistance level of new varieties as well as to validate MAS selection. In this study, the Rpv mediated defense responses were investigated in 31 genotypes, encompassing susceptible and resistant varieties and 26 seedlings, following inoculation of leaf discs with P. viticola. The offspring differed in Rpv loci inherited (none, one or two): Rpv3-3 and Rpv10 from Solaris and Rpv3-1 and Rpv12 from Kozma 20-3. To improve the assessment of different resistance responses, pathogen reaction (sporulation) and host reaction (necrosis) were scored separately as independent features. They were differently expressed depending on Rpv locus: offspring carrying Rpv3-1 and Rpv12 loci showed the strongest resistance response (scarce sporulation and necrosis), those carrying Rpv3-3 locus showed the highest levels of necrosis while Rpv10 carrying genotypes showed intermediate levels of both sporulation and necrosis.
| S-EPMC7356695 | biostudies-literature
Project description:Plant resistance to biotrophic pathogens is classically believed to be mediated through salicylic acid (SA) signaling leading to hypersensitive response followed by the establishment of Systemic Acquired Resistance. Jasmonic acid (JA) signaling has extensively been associated to the defense against necrotrophic pathogens and insects inducing the accumulation of secondary metabolites and PR proteins. Moreover, it is believed that plants infected with biotrophic fungi suppress JA-mediated responses. However, recent evidences have shown that certain biotrophic fungal species also trigger the activation of JA-mediated responses, suggesting a new role for JA in the defense against fungal biotrophs. Plasmopara viticola is a biotrophic oomycete responsible for the grapevine downy mildew, one of the most important diseases in viticulture. In this perspective, we show recent evidences of JA participation in grapevine resistance against P. viticola, outlining the hypothesis of JA involvement in the establishment of an incompatible interaction with this biotroph. We also show that in the first hours after P. viticola inoculation the levels of OPDA, JA, JA-Ile, and SA increase together with an increase of expression of genes associated to JA and SA signaling pathways. Our data suggests that, on the first hours after P. viticola inoculation, JA signaling pathway is activated and the outcomes of JA-SA interactions may be tailored in the defense response against this biotrophic pathogen.
| S-EPMC4848468 | biostudies-literature
Project description:The Plasmopara viticola pathogen causes one of the most severe grapevine diseases, namely downy mildew. The response to P. viticola involves both visible symptoms and intricate metabolomic alterations, particularly in relation to volatile organic compounds, and depends on the degree of resistance of a particular variety. There are numerous native grapevine varieties in Croatia, and they vary in susceptibility to this oomycete. As previously reported, in vitro leaf disc bioassay and polyphenolic compound analysis are complementary methods that can be used to separate native varieties into various resistance classes. This research used the Solid Phase Microextraction-Arrow Gas Chromatography-Mass Spectrometry method to identify the early alterations in the VOCs in the leaves after P. viticola inoculation. Based on the absolute peak area of sesquiterpenes, some discrepancies between the sampling terms were noticed. The presence of certain chemical compounds such as humulene, ylangene, and α-farnesene helped distinguish the non-inoculated and inoculated samples. Although specific VOC responses to P. viticola infection of native varieties from various resistance classes could not be identified, the response of less susceptible native varieties and resistant controls was associated with an increase in the absolute peak area of several compounds, including geranylacetone, ß-ocimene, and (E)-2-hexen-1-ol.
| S-EPMC9863345 | biostudies-literature
Project description:Plasmopara viticola, the causal agent of grapevine downy mildew, is one of the most devastating grape pathogen in Europe and North America. Although phytochemicals are used to control pathogen infections, the appearance of resistant strains and the concern for possible adverse effects on environment and human health are increasing the search for alternative strategies. In the present investigation, we successfully tested two protein hydrolysates from soybean (soy) and casein (cas) to trigger grapevine resistance against P. viticola. On Vitis vinifera cv. Marselan plants, the application of soy and cas reduced the infected leaf surface by 76 and 63%, as compared to the control, respectively. Since both hydrolysates might trigger the plant immunity, we investigated their ability to elicit grapevine defense responses. On grapevine cell suspensions, a different free cytosolic calcium signature was recorded for each hydrolysate, whereas a similar transient phosphorylation of two MAP kinases of 45 and 49 kDa was observed. These signaling events were followed by transcriptome reprogramming, including the up-regulation of defense genes encoding pathogenesis-related (PR) proteins and the stilbene synthase enzyme responsible for the biosynthesis of resveratrol, the main grapevine phytoalexin. Liquid chromatography analyses confirmed the production of resveratrol and its dimer metabolites, δ- and ε-viniferins. Overall, soy effects were more pronounced as compared to the cas ones. Both hydrolysates proved to act as elicitors to enhance grapevine immunity against pathogen attack.
| S-EPMC4274885 | biostudies-literature
Project description:Plasmopara viticola, the downy mildew pathogen, is one of the most important pathogens in European viticulture. This oomycete infects grapevine leaves via zoospores that encyst at stomata. A primary germ tube then enters the substomatal cavity and develops a tubular network of hyphae that proliferate intercellularly and parasitize the leaf mesophyll cells by haustoria. Leaf infections have thus been the primary object of multiple studies concerning the physiology of the pathogen and defense reactions of grapevines. Besides leaves, this oomycete pathogen is able to spread throughout the plant tissue. As shown here by microscopy, it colonizes leaf petioles, shoots, berries and seeds. Evidence is provided showing that this process is facilitated by formation of special fan-shaped hyphae that seem to be necessary to overcome physical barriers in plant tissues. Physical obstacles are mainly constituted by vascular tissue in leaf veins, leaf petioles and shoots. In grapevine shoots, the mycelium seems to extend along the cambial layer between xylem and phloem tissue. Infected young berries are completely colonized on the inside. Older infected "leather berries" show glossy appositions of the fan-shaped hyphae at the inner side of the berry skin. The seeds from that stage of infestation are devoid of endosperm and embryo and biologically dysfunctional. Furthermore, a classification system for P. viticola infection based on the degree of infections in petioles and shoot tips is presented. This study contributes to a better understanding of downy mildew pathogenesis in grapevine, a prerequisite for efficient control measures.
| S-EPMC6667660 | biostudies-literature
Project description:Accurate localization of phytoalexins is a key for better understanding their role. This work aims to localize stilbenes, the main phytoalexins of grapevine. The cellular localization of stilbene fluorescence induced by Plasmopara viticola, the agent of downy mildew, was determined in grapevine leaves of very susceptible, susceptible, and partially resistant genotypes during infection. Laser scanning confocal microscopy and microspectrofluorimetry were used to acquire UV-excited autofluorescence three-dimensional images and spectra of grapevine leaves 5-6 days after inoculation. This noninvasive technique of investigation in vivo was completed with in vitro spectrofluorimetric studies on pure stilbenes as their fluorescence is largely affected by the physicochemical environment in various leaf compartments. Viscosity was the major physicochemical factor influencing stilbene fluorescence intensity, modifying fluorescence yield by more than two orders of magnitude. Striking differences in the localization of stilbene fluorescence induced by P. viticola were observed between the different genotypes. All inoculated genotypes displayed stilbene fluorescence in cell walls of guard cells and periclinal cell walls of epidermal cells. Higher fluorescence intensity was observed in guard-cell walls than in any other compartment due to increased local viscosity. In addition stilbene fluorescence was found in epidermal cell vacuoles of the susceptible genotype and in the infected spongy parenchyma of the partially resistant genotype. The very susceptible genotype was devoid of fluorescence both in the epidermal vacuoles and the mesophyll. This strongly suggests that the resistance of grapevine leaves to P. viticola is correlated with the pattern of localization of induced stilbenes in host tissues.
| S-EPMC3388817 | biostudies-other
Project description:Six components of partial resistance (RCs) were studied in 15 grapevine varieties with partial resistance to Plasmopara viticola: (i) infection frequency (IFR, proportion of inoculation sites showing sporulation), (ii) latent period (LP50, degree-days between inoculation and appearance of 50% of the final number of sporulating lesions), (iii) lesion size (LS, area of single lesions in mm2), (iv) production of sporangia (SPOR, number of sporangia produced per lesion, and SPOR', number of sporangia produced per mm2 of lesion), (v) infectious period (IP, number of sporulation events on a lesion), and (vi) infectivity of sporangia (INF, infection efficiency of sporangia produced on resistant varieties). Artificial inoculation monocycle experiments were conducted for a 3-year period on leaves collected at leaf development, flowering, and fruit development. Compared to the susceptible variety 'Merlot', the partially resistant varieties showed reduced IFR, longer LP, smaller LS, fewer SPOR and SPOR', shorter IP, and lower INF. At leaf development, IFR, SPOR, and INF were higher and LP was shorter than at flowering and fruit development. RCs analysis through monocyclic experiments provides reliable assessments of the resistance response of grapevine accessions. The workload required for routine assessment in breeding programs could be reduced by measuring IFR and SPOR, while producing robust results.
| S-EPMC6969139 | biostudies-literature
Project description:Downy mildew, caused by the biotrophic oomycete Plasmopara viticola, is one of the most economically significant grapevine diseases worldwide. Current strategies to cope with this threat rely on the massive use of chemical compounds during each cultivation season. The economic costs and negative environmental impact associated with these applications increased the urge to search for sustainable strategies of disease control. Improved knowledge of plant mechanisms to counteract pathogen infection may allow the development of alternative strategies for plant protection. Epigenetic regulation, in particular DNA methylation, is emerging as a key factor in the context of plant-pathogen interactions associated with the expression modulation of defence genes. To improve our understanding of the genetic and epigenetic mechanisms underpinning grapevine response to P. viticola, we studied the modulation of both 5-mC methylation and gene expression at 6 and 24 h post-infection (hpi). Leaves of two table grape genotypes (Vitis vinifera), selected by breeding activities for their contrasting level of susceptibility to the pathogen, were analysed. Following pathogen infection, we found variations in the 5-mC methylation level and the gene expression profile. The results indicate a genotype-specific response to pathogen infection. The tolerant genotype (N23/018) at 6 hpi exhibits a lower methylation level compared to the susceptible one (N20/020), and it shows an early modulation (at 6 hpi) of defence and epigenetic-related genes during P. viticola infection. These data suggest that the timing of response is an important mechanism to efficiently counteract the pathogen attack.
| S-EPMC9826190 | biostudies-literature
Project description:Subtilisin-like proteases, also known as subtilases, are a very diverse family of serine peptidases present in many organisms. In grapevine, there are hints of the involvement of subtilases in defense mechanisms, but their role is not yet understood. The first characterization of the subtilase gene family was performed in 2014. However, simultaneously, the grapevine genome was re-annotated and several sequences were re-annotated or retrieved. We have performed a re-characterization of this family in grapevine and identified 82 genes coding for 97 putative proteins, as result of alternative splicing. All the subtilases identified present the characteristic S8 peptidase domain and the majority of them also have a pro-domain I9 inhibitor, a protease-associated (PA) domain, and a signal peptide for targeting to the secretory pathway. Phylogenetic studies revealed six subtilase groups denominated VvSBT1 to VvSBT6. As several evidences have highlighted the participation of plant subtilases in response to biotic stimulus, we have investigated subtilase participation in grapevine resistance to Plasmopara viticola, the causative agent of downy mildew. Fourteen grapevine subtilases presenting either high homology to P69C from tomato, SBT3.3 from Arabidopsis thaliana or located near the Resistance to P. viticola (RPV) locus were selected. Expression studies were conducted in the grapevine-P. viticola pathosystem with resistant and susceptible cultivars. Our results may indicate that some of grapevine subtilisins are potentially participating in the defense response against this biotrophic oomycete.
| S-EPMC5122586 | biostudies-literature