Induced Plant Defense Research Articles

Life Table and Preference Choice of Frankliniella occidentalis (Thysanoptera: Thripidae) for Kidney Bean Plants Treated by Exogenous Calcium.

Simple SummaryWestern flower thrips, Frankliniella occidentalis, is an invasive key pest that damages vegetables and ornamentals worldwide. The activation of induced resistance by chemicals may provide a simple and feasible way of achieving improvement of resistance to stress in crop plants, which is an important technology for the development of sustainable agriculture. Calcium (Ca) is an essential element for plants; numerous studies have shown that Ca can confer crop plants with resistance to abiotic and biotic stresses. For the first time, we report the negative effects of exogenous Ca on kidney bean plants in relation to the performance of F. occidentalis, including a reduced preference of thrips. Therefore, Ca could potentially be used to control F. occidentalis.Exogenous calcium (Ca) has been used to induce host plant resistance in response to abiotic and biotic stresses, including from thrips attack. The aim of this study was to determine whether exogenously applied Ca affects the performance of Frankliniella occidentalis. We assessed the development time, total longevity, reproduction, and population parameters of F. occidentalis, and its preference choice on Ca-treated or untreated control kidney bean plants under laboratory conditions. The results showed that F. occidentalis fed on Ca-treated leaves had a longer developmental time but lower longevity (female and male) and fecundity than F. occidentalis fed on control leaves. Population parameters, including the intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R0), were all found higher in control leaves than in Ca-treated leaves, and the mean generation time (T) was shorter. In preference choices, the number of thrips on control plants was higher than the number of thrips on Ca-treated kidney bean plants. Overall, our results indicated that exogenous Ca pretreatment on kidney bean plants affected the life history and preference choice of F. occidentalis, suggesting Ca might be used as a promising elicitor of inducible plant defense against thrips.

The Use of Biochar for Plant Pathogen Control.

To support the search for alternative, nonchemical plant disease control strategies, we present a review of the pathogen-suppressive effects of biochar, a product derived from agricultural and other organic wastes, used as a soil amendment. A wide range of biochar effects contribute to the control of root or foliar fungal pathogens through modification of root exudates, soil properties, and nutrient availability, which influence the growth of antagonist microorganisms. The induction of systemic plant defenses by biochar in the roots to reduce foliar pathogenic fungi, the activation of stress-hormone responses, as well as changes in active oxygen species are indicative of a coordinated hormonal signaling within the plant. Although scarce data are available for oomycetes and bacterial pathogens, reports indicate that biochar promotes changes in the soil microbiota influencing pathogen motility and colonization, and the induction of plant systemic defenses, both contributing to disease suppression. Biochar also suppresses nematode and insect pests. For plant-parasitic nematodes, the primary modes of action are changes in soil microbial community diversity, the release of nematicidal compounds, and the induction of plant defenses. Use of biochar-based soil amendments is a promising strategy compatible with a circular economy, based on zero waste, as part of integrated pathogen and pest management. Since biochars exert complex and distinct modes of action for the control of plant pathogens, its nature and application regimes should be designed for particular pathogens and its effects studied locally.

Isolation and identification of Amycolatopsis sp. strain 1119 with potential to improve cucumber fruit yield and induce plant defense responses in commercial greenhouse

The application of chemical fungicides is the first strategy to control plant fungal diseases. This approach is highly polluting for the environment and affects human health. The artificial introduction of beneficial rhizobacteria into the soil can be an economical and practical way to control phytopathogenic fungi in commercial greenhouses. Here, we recount the travel of a rare Actinomycete (Amycolatopsis strain 1119) from a maize field to a commercial cucumber greenhouse. Culturable bacteria from rhizosphere and bulk soils of dicot and monocot crops were isolated and screened. About 20% of the representative colonies showed Actinobacteria appearance. 106 Actinobacteria that had antagonistic activity against Phytophthora capsici and were able to produce IAA-like molecules were selected for further analysis. Two Streptomyces strains (432 and 615) and 2 Amycolatopsis strains (3513 and 1119) that showed a positive effect on plant growth in greenhouse conditions were selected to evaluate the biocontrol potential. Strains 432, 3513, 615 and 1119 controlled incidence of the damping-off by 65%, 42%, 83% and 100% respectively. Application of strain 1119 under commercial greenhouse conditions resulted in an increase in fruit yield (20%) and a decrease in fruit nitrate content (70%). Increased antioxidant enzymes activity and increased LOX and APX transcription and also, increased expression of two genes PR1-1a and GLU (SAR genes) showed that strain 1119 could induce both ISR and SAR in cucumber without pathogen exposure. Our results demonstrate that the Amycolatopsis strain 1119 has a great potential to be used as an active principle for bio-inoculant development because of the ability to improve cucumber fruit yield and induce plant defense responses in a commercial greenhouse.

Methyl jasmonate‐induced resistance to Delia platura (Diptera: Anthomyiidae) in Lupinus mutabilis

Andean lupin (Lupinus mutabilis Sweet) is an important leguminous crop from South America with a high protein content. In Ecuador, lupin yields are severely affected by the infestation of Delia platura larvae on germinating seeds. The application of elicitor molecules with activity against herbivorous insects to control D. platura infestation constitutes an unexplored and promising alternative for chemical insecticides. In this study, methyl jasmonate (MeJA), hexanoic acid, menadione sodium bisulfite, and DL-β-aminobutyric acid were evaluated for their ability to induce resistance against D. platura in three commercial lupin cultivars. Only seeds pretreated with MeJA significantly impaired insect performance during choice and no-choice assays. Additionally, fitness indicators such as seed germination and growth were not affected by MeJA treatment. To investigate the molecular mechanisms behind the MeJA-mediated resistance, RT-qPCR assays were performed. First, RT-qPCR reference genes were validated, showing that LmUBC was the most stable reference gene. Next, expression analysis over time revealed that MeJA application up-regulated the activity of the jasmonic acid biosynthetic genes LmLOX2 and LmAOS, together with other jasmonate-related defense genes, such as LmTPS1, LmTPS4, LmPI2, LmMBL, LmL/ODC, LmCSD1, and LmPOD. This study indicates that MeJA can be used as an environmentally friendly elicitor molecule to protect Andean lupin from D. platura attack without fitness cost. MeJA application induces plant defense responses to insects in Andean lupin that may be modulated by the onset of terpenoid biosynthesis, proteinase inhibitors, lectins, polyamines, and antioxidative enzymes. © 2021 Society of Chemical Industry.

Identification of Riptortuspedestris Salivary Proteins and Their Roles in Inducing Plant Defenses.

Simple SummaryThe bean bug, Riptortus pedestris (Fabricius) is a notorious pest of soybean crops in Asia. During the feeding process, the bug secretes a mixture of salivary components, which play critical roles in the insect–plant interactions. In the present study, a total of 136 salivary proteins were identified by transcriptomic and proteomic approaches. Among them, five proteins (RpSP10.3, RpSP13.4, RpSP13.8, RpSP17.8, and RpSP10.2) were capable of inducing cell death, reactive oxygen species (ROS) burst, and hormone signal changes, indicating the potential roles of these proteins in eliciting plant defenses. Our results provide a good resource for future functional studies of bug salivary effectors and might be useful in pest management.The bean bug, Riptortus pedestris (Fabricius), is one of the most important soybean pests. It damages soybean leaves and pods with its piercing-sucking mouthparts, causing staygreen-like syndromes in the infested crops. During the feeding process, R. pedestris secretes a mixture of salivary proteins, which play critical roles in the insect–plant interactions and may be responsible for staygreen-like syndromes. The present study aimed to identify the major salivary proteins in R. pedestris saliva by transcriptomic and proteomic approaches, and to screen the proteins that potentially induced plant defense responses. Altogether, 136 salivary proteins were identified, and a majority of them were involved in hydrolase and binding. Additionally, R. pedestris saliva contained abundant bug-specific proteins with unknown function. Transient expression of salivary proteins in Nicotiana benthamiana leaves identified that RpSP10.3, RpSP13.4, RpSP13.8, RpSP17.8, and RpSP10.2 were capable of inducing cell death, reactive oxygen species (ROS) burst, and hormone signal changes, indicating the potential roles of these proteins in eliciting plant defenses. Our results will shed more light on the molecular mechanisms underlying the plant–insect interactions and are useful for pest management.

Effect of Salicylic AcidFormulations on Induced Plant Defense against Cassava Anthracnose Disease.

This study was to investigate defense mechanisms on cassava induced by salicylic acid formulation (SA) against anthracnose disease. Our results indicated that the SA could reduce anthracnose severity in cassava plants up to 33.3% under the greenhouse condition. The β-1,3-glucanase and chitinase enzyme activities were significantly increased at 24 hours after inoculation (HAI) and decrease at 48 HAI after Colletotrichum gloeosporioides challenge inoculation, respectively, for cassava treated with SA formulation. Synchrotron radiation–based Fourier-transform infrared microspectroscopy spectra revealed changes of the C=H stretching vibration (3,000–2,800 cm−1), pectin (1,740–1,700 cm−1), amide I protein (1,700–1,600 cm−1), amide II protein (1,600–1,500 cm−1), lignin (1,515 cm−1) as well as mainly C–O–C of polysaccharides (1,300–1,100 cm−1) in the leaf epidermal and mesophyll tissues treated with SA formulations, compared to those treated with fungicide carbendazim and distilled water after the challenged inoculation with C. gloeosporioides. The results indicate that biochemical changes in cassava leaf treated with SA played an important role in the enhancement of structural and chemical defense mechanisms leading to reduced anthracnose severity.

A Small Cysteine-Rich Phytotoxic Protein of Phytophthora capsici Functions as Both Plant Defense Elicitor and Virulence Factor.

Small cysteine-rich (SCR) proteins, including fungal avirulence proteins, play important roles in pathogen-plant interactions. SCR protein-encoding genes have been discovered in the genomes of Phytophthora pathogens but their functions during pathogenesis remain obscure. Here, we report the characterization of one Phytophthora capsici SCR protein (namely, SCR82) with similarity to Phytophthora cactorum phytotoxic protein PcF. The scr82 gene has 10 allelic sequences in the P. capsici population. Homologs of SCR82 were not identified in fungi or other organisms but in Phytophthora relative species. Initially, scr82 was weakly expressed during the mycelium, sporangium, and zoospore stages but quickly upregulated when the infection initiated. Both ectopic expression of SCR82 and recombinant yeast-expressed protein (rSCR82) caused cell death on tomato leaves. Upon treatment, rSCR82 induced plant defense responses, including the induction of defense gene expression, reactive oxygen species burst, and callose deposition. Knockout of scr82 in P. capsici by CRISPR/Cas9 severely impaired its virulence on host plants and significantly reduced its resistance against oxidative stress. Inversely, its overexpression increased the pathogen's virulence and tolerance to oxidative stress. Our results collectively demonstrate that SCR82 functions as both an important virulence factor and plant defense elicitor, which is conserved across Phytophthora spp.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Foliar selenium application reduces late blight severity and incidence in potato and acts as a pathogen growth inhibitor and elicitor of induced plant defence

Late blight caused by Phytophthora infestans is a serious threat to potato production. Currently, solutions to manage late blight in organic systems are scarce. This study was undertaken to evaluate the effect of selenium (Se) on plant emergence from seed pre-treated with Se and the seed decay pathogens Pectobacterium carotovorum ssp. carotovorum and Fusarium sambucinum, and on foliar potato late blight following inoculation with P. infestans and foliar treatment with Se. The potential modes of action of Se were also evaluated. Following inoculation of the seed decay pathogens on potato seed pre-treated with different rates of Se, plant emergence was not affected by Se treatment. By pre-treating potato seed with different Se rates, and applying different foliar Se rates on potato plants subsequently inoculated with the late blight pathogen in a greenhouse setting, we showed that foliar Se application alone or combined with Se seed treatment reduced the severity and incidence of late blight, and activated the production of secondary metabolites in potato leaves and tubers. Further, in vitro studies showed that Se directly inhibited the mycelial growth of P. infestans and other important plant pathogens, including Fusarium graminearum and Sclerotinia sclerotiorum. The data suggest that Se acts as an inducer of plant defences, while also inhibiting fungal growth. The study highlights the potential of Se for managing late blight, and suggests that its application could contribute to improving plant health in greenhouse production systems by helping to control diseases caused by P. infestans, F. graminearum and S. sclerotiorum.

Protection of tomato plants against Fusarium oxysporum f. sp. lycopersici induced by chitosan

Physiological processes of plants infected by vascular pathogens are mainly affected by vascular bundle obstruction, decreasing the absorption of water and nutrients and gas exchange by stomatal closure, and inducing oxidative cascades and PSII alterations. Chitosan, a derivative of chitin present in the cell wall of some organisms including fungi, induces plant defense responses, activating systemic resistance. In this study, three chitosan molecules (low, medium and high molecular weight) at different concentrations (0.5, 1, 1.5, 2, 2.5 and 3 mg mL-1) were assessed by in vitro tests against Fusarium oxysporum f. sp. lycopersici (Fol). Concentrations higher than 1 mg mL-1 were found to inhibit significantly the mycelial growth of Fol, with 95.8% of inhibition using chitosan with high molecular weight (3 mg mL-1). For in planta assays, chitosan treatment (low molecular weight 2.5 mg mL-1) showed significantly lower incidence and severity of wilting disease symptoms, 70 and 91%, respectively, compared to healthy plants used as a negative control. The effect of chitosan on the physiological and molecular responses of tomato plants infected with Fol was studied, evaluating the maximum potential quantum efficiency of PSII photochemistry (Fv/Fm), photochemical efficiency of PSII (Y(II)), stomatal conductance (gs), relative water content (RWC), proline content, photosynthetic pigments, dry mass, and differential gene expression (PAL, LOXA, ERF1, and PR1) of defense markers. A reduction of 70% in the incidence and 91% in the severity of the disease was achieved in plants treated with chitosan, mitigating the damage caused by Fol on Fv/Fm, Y(II), and chlorophyll contents by 23, 36, and 47%, respectively. Less impact was observed on gs, RWC, and dry mass (55, 11, and 26%, respectively). Chitosan-treated and Fol-infected plants over-expressed PR1a gene suggesting a priming-associated response. These results demonstrate the high potential of chitosan to protect tomato plants against Fol by regulating physiological and molecular responses in tomato plants.

The Effects of Biostimulants on Induced Plant Defense

The search for innovative and alternative methods for chemical control to manage pests is an increasingly growing reality. The use of biostimulants such as plant growth promoting rhizobacteria (PGPR) and humic acids (HA) has been shown to improve many agronomic characteristics of plants while increasing yield. These biostimulants also alter the production of secondary metabolites with consequences for insect herbivores. Here we review the role of biostimulants such as PGPR and HA in promoting and eliciting plant defenses. The cascading effects of using these biostimulants on insect herbivores and their natural enemies are discussed in this context. Synergism between biostimulants are also discussed. The potential role of these products in augmenting agricultural productivity is highlighted as is further need for additional research. This review highlights the potential of this tool to enhance integrated pest management in agricultural production systems, reduce the use of pesticides, and increase the efficiency of fertilization while supporting healthier more pest-resistant plants.

Comparing Exogenous Methods to Induce Plant-Resistance Against a Bark-Feeding Insect

Exogenous application of the plant hormone methyl jasmonate (MeJA) can trigger induced plant defenses against herbivores, and has been shown to provide protection against insect herbivory in conifer seedlings. Other methods, such as mechanical damage to seedlings, can also induce plant defenses, yet few have been compared to MeJA and most studies lack subsequent herbivory feeding tests. We conducted two lab experiments to: (1) compare the efficacy of MeJA to mechanical damage treatments that could also induce seedling resistance, (2) examine if subsequent insect damage differs depending on the time since induction treatments occurred, and (3) assess if these induction methods affect plant growth. We compared Scots pine (Pinus sylvestris) seedlings sprayed with MeJA (10 or 15 mM) to seedlings subjected to four different mechanical bark damage treatments (two different bark wound sizes, needle-piercing damage, root damage) and previous pine weevil (Hylobius abietis) damage as a reference treatment. The seedlings were exposed to pine weevils 12 or 32 days after treatments (early and late exposure, hereafter), and resistance was measured as the amount of damage received by plants. At early exposure, seedlings treated with needle-piercing damage received significantly more subsequent pine weevil feeding damage than those treated with MeJA. Seedlings treated with MeJA and needle-piercing damage received 84% less and 250% more pine weevil feeding, respectively, relative to control seedlings. The other treatments did not differ statistically from control or MeJA in terms of subsequent pine weevil damage. For the late exposure group, plants in all induction treatments tended to receive less pine weevil feeding (yet this was not statistically significant) compared to control seedlings. On the other hand, MeJA significantly slowed down seedling growth relative to control and all other induction treatments. Overall, the mechanical damage treatments appeared to have no or variable effects on seedling resistance. One of the treatments, needle-piercing damage, actually increased pine weevil feeding at early exposure. These results therefore suggest that mechanical damage shows little potential as a plant protection measure to reduce feeding by a bark-chewing insect.

Exploring Two Streptomyces Species to Control Rhizoctonia solani in Tomato

Streptomyces species are effective biocontrol agents toward many plant pathogens. These microorganisms are well known for producing secondary metabolites, promoting plant growth and inducing plant defense mechanisms. In this study, the ability of tomato root-colonizing Streptomyces strains to trigger the resistance against Rhizoctonia solani (J.G. Kühn) AG4 was investigated. For this goal, we evaluated the pattern of LOXB and PAL1 genes expression changes upon pathogen inoculation in primed tomato plants. The results revealed that Streptomyces globisporous (Krasil’nikov) strain F8 and S. praecox (Millard and Burr) strain R7 were able to enhance the expression of lipoxygenase and phenylalanine ammonia lyase in tomato plants. This finding suggests that Streptomyces strains F8 and R7 may trigger jasmonic acid and phenyl propanoid signaling pathways in plants, therefore, resulting an induced defense status in tomatoes against R. solani. Biochemical characterization of these Streptomyces strains showed that they were strong producers of siderophores. S. praecox strain R7 produced siderophores of hyderoxamate and catechol types and S. globisporous strain F8 produced a phenolic siderophore. Moreover, they also produced protease while only the S. praecox strain R7 was able to produce amylase. Taken together, these results indicate that S. globisporous strain F8 and S. praecox strain R7 promote plant growth and reduces disease and hence are suitable for future in depth and field studies with the aim to attain appropriate biocontrol agents to protect tomatoes against R. solani.

The non-sulfated ulvanobiuronic acid of ulvans is the smallest active unit able to induce an oxidative burst in dicot cells

Ulvans from green algae are promising compounds for plant protection because they are environmentally friendly and induce plant defense responses. We analyzed the structure-function relationship of ulvan polymers and oligomers for their elicitor activity in suspension-cultured cells of three dicot species. The polysaccharide from Ulva fasciata was characterized regarding its monosaccharide composition, degree of sulfation, and molecular mass. The polymer was partially depolymerized using acid hydrolysis, and the oligomers were separated using size exclusion chromatography. The oligomeric fractions were analyzed revealing mostly sulfated and de-sulfated ulvan dimers. Both the polymer and the oligomer fractions induced an NADPH oxidase-dependent oxidative burst in plant cells. The elicitor activity of the ulvan dimers did not require sulfation. By identifying the smallest elicitor-active unit, HexA-Rha, we took an important next step to understand how the structure influences ulvan elicitor responses. The desulfated ulvan dimer is discussed as a promising agro-biologic for sustainable agriculture.

How to Unravel the Key Functions of Cryptic Oomycete Elicitin Proteins and Their Role in Plant Disease.

Pathogens and plants are in a constant battle with one another, the result of which is either the restriction of pathogen growth via constitutive or induced plant defense responses or the pathogen colonization of plant cells and tissues that cause disease. Elicitins are a group of highly conserved proteins produced by certain oomycete species, and their sterol binding ability is recognized as an important feature in sterol–auxotrophic oomycetes. Elicitins also orchestrate other aspects of the interactions of oomycetes with their plant hosts. The function of elicitins as avirulence or virulence factors is controversial and is dependent on the host species, and despite several decades of research, the function of these proteins remains elusive. We summarize here our current understanding of elicitins as either defense-promoting or defense-suppressing agents and propose that more recent approaches such as the use of ‘omics’ and gene editing can be used to unravel the role of elicitins in host–pathogen interactions. A better understanding of the role of elicitins is required and deciphering their role in host–pathogen interactions will expand the strategies that can be adopted to improve disease resistance and reduce crop losses.

Heat-killed endophytic bacterium induces robust plant defense responses against important pathogens

Stress caused by pathogens strongly damages plants. Developing products to control plant disease is an important challenge in sustainable agriculture. In this study, a heat-killed endophytic bacterium (HKEB), Bacillus aryabhattai, is used to induce plant defense against fungal and bacterial pathogens, and the main defense pathways used by the HKEB to activate plant defense are revealed. The HKEB induced high protection against different pathogens through the salicylic and jasmonic acid pathways. We report the presence of gentisic acid in the HKEB for the first time. These results show that HKEBs may be a useful tool for the management of plant diseases.

Temperature Differentially Influences the Capacity of Trichoderma Species to Induce Plant Defense Responses in Tomato Against Insect Pests

Temperature Differentially Influences the Capacity of Trichoderma Species to Induce Plant Defense Responses in Tomato Against Insect Pests

Temperature Differentially Influences the Capacity of Trichoderma Species to Induce Plant Defense Responses in Tomato Against Insect Pests.

Species of the ecological opportunistic, avirulent fungus, Trichoderma are widely used in agriculture for their ability to protect crops from the attack of pathogenic fungi and for plant growth promotion activity. Recently, it has been shown that they may also have complementary properties that enhance plant defense barriers against insects. However, the use of these fungi is somewhat undermined by their variable level of biocontrol activity, which is influenced by environmental conditions. Understanding the source of this variability is essential for its profitable and wide use in plant protection. Here, we focus on the impact of temperature on Trichoderma afroharzianum T22, Trichoderma atroviride P1, and the defense response induced in tomato by insects. The in vitro development of these two strains was differentially influenced by temperature, and the observed pattern was consistent with temperature-dependent levels of resistance induced by them in tomato plants against the aphid, Macrosiphum euphorbiae, and the noctuid moth, Spodoptera littoralis. Tomato plants treated with T. afroharzianum T22 exhibited enhanced resistance toward both insect pests at 25°C, while T. atroviride P1 proved to be more effective at 20°C. The comparison of plant transcriptomic profiles generated by the two Trichoderma species allowed the identification of specific defense genes involved in the observed response, and a selected group was used to assess, by real-time quantitative reverse transcription PCR (qRT-PCR), the differential gene expression in Trichoderma-treated tomato plants subjected to the two temperature regimens that significantly affected fungal biological performance. These results will help pave the way toward a rational selection of the most suitable Trichoderma isolates for field applications, in order to best face the challenges imposed by local environmental conditions and by extreme climatic shifts due to global warming.

Effect of foliar application of different elicitors on occurrence of pest and diseases during chia (Salvia hispanica L.) cultivation

Chia is an important medicinal crop with lot of nutritional value in seeds and there is lot of demand to chia seeds grown without any chemical application. In this context, present study was concentrated on foliar application of different elicitors at 25 and 50 days after sowing as effective plant protectants by inducing plant defense response. Both black and white chia plants sprayed with chitosan at 200 ppm were un-affected by any pest and diseases. The plants sprayed with other elicitors like 100 ppm of salicylic acid, methyl jasmonic acid, potassium silicate, 200 ppm of boric acid, humic acid and 5000 ppm of dry yeast and PGPR are less prone to pest and disease attack. Whereas, the maximum pest infestation and disease incidence were noticed in plants sprayed with gibberellic acid (pest - 2.38 and 1.93%; disease - 0.89% in both) and in control (pest - 1.34 and 1.04%; disease - 1.34 and 0.74%) in black and white chia respectively.

Plant Biostimulants: New Insights Into the Biological Control of Verticillium Wilt of Olive.

Verticillium wilt of olive (Olea europaea subsp. europaea L.) (VWO), caused by the hemibiotrophic soil-borne fungus Verticillium dahliae Kleb., is considered the major limiting factor of this crop in Mediterranean-type climate regions of the world. The absence of effective chemical treatments makes the control of the disease difficult. In this way, the use of biostimulants and host plant defense inducers seems to be one of the most promising biological and eco-friendly alternatives to traditional control measures. Thus, the main goal of this study was to evaluate the effect of 32 products, including amino acids, micronutrients, microorganisms, substances of natural origin, copper complex-based products, and organic and inorganic salts against the disease under controlled conditions. To this end, their effects on mycelial growth and microsclerotia (MS) inhibition of V. dahliae were evaluated by means of dual cultures or by sensitivity tests in vitro as well as on disease progression in planta. Wide ranging responses to the pathogen and disease reduction levels were observed among all the products tested, suggesting multiple modes of action. Copper-based products were among the most effective for mycelial growth and MS inhibition, whereas they did not show an important effect on the reduction of disease severity in planta. Phoma sp. and Aureobasidium pullulans were the most effective in disease reduction in planta with foliar application. On the other hand, two phosphite salts, one with copper and the other with potassium, were the most effective in disease reduction in planta when they were applied by irrigation, followed by A. pullulans and Bacillus amyloliquefaciens. This study will be useful to select the best candidates for future studies, contributing significantly to new insights into the current challenge of the biological control of VWO.

Methyl salicylate, a grape and wine chemical marker and sensory contributor in wines elaborated from grapes affected or not by cryptogamic diseases

Methyl salicylate (MeSA) is a plant metabolite that induces plant defence resistance and an odorous volatile compound presenting green nuances. This volatile compound was shown to be present in wine samples, sometimes at concentrations above its olfactory detection threshold. MeSA is localized in grapes, particularly in the skins and stems, and is extracted during red wine vinification. It was detected at the highest concentrations in wines of several grape varieties, made from grapes affected by cryptogamic diseases, namely downy mildew caused by Plasmopara viticola, and black rot caused by Guignardia bidwellii. It has also been detected in wines from vines affected by Esca, a Grapevine Trunk Disease. MeSA can also be considered to be a chemical marker in grapes and wine indicative of the level of development of several vine cryptogamic diseases.