Phylloxera Infestation Research Articles

Grafting Genotype Combination Effect of Vitis ssp. on Roots Phylloxeration Degree and Vigor of Grapevine

The present study investigated whether different grafting combinations (hypobiont-epibiont) of Vitis spp. influence root infection with phylloxera and thus vine biomass on potted 2-year-old plants. The study was conducted simultaneously at two locations in Slovenia (VEM) and Hungary (GF). The dormant canes of ‘Johanniter’ (JOH), ‘Riesling’ (RR) and Vitis berlandieri × Vitis riparia ‘Teleki 5C’ (5C) were hetero-grafted (each with each) and autografted (each with itself), so that nine plant combinations were used for the trial. The roots of the experimental plants at different ages (1–2 years) were infested with two phylloxera populations originating from two locations (VEM, GF). Plant growth was quantified 120 days after inoculation by measuring root and shoot biomass, while the extent of phylloxera infestation was assessed by the number of feeding sites (nodosities, tuberosities) and the number of larval stages of phylloxera. In most cases, the genotype of the hypobiont influenced the degree of phylloxera infestation on all roots of the two-year-old root system. At both locations, the highest number of nodosities and the highest increase in phylloxera population was observed on the autografted Teleki 5C (5C/5C). The phylloxera biotype derived from Vitis vinifera roots (GF) induced tuberosities, especially on roots of combinations where JOH and RR were used as hypobionts. No correlation was found between biomass and phylloxera infestation. The hypobiont genotype had no effect on cane biomass at the end of the growth cycle at either experimental site.

ОСНОВНЫЕ ИТОГИ НАУЧНО-ИССЛЕДОВАТЕЛЬСКОЙ РАБОТЫ ДАГЕСТАНСКОЙ СЕЛЕКЦИОННОЙ ОПЫТНОЙ СТАНЦИИ ВИНОГРАДАРСТВА И ОВОЩЕВОДСТВА ЗА 2023 ГОД

The article presents the main results of the research work of scientists of the DBESVVG – branch of NCFSCHVW, carried out in accordance with the State Task for 2023 and the Research Plan for 2022-2026 on the basis of the PFSR of the state Academies of Sciences for 2021-2030. The research results reflect the main directions of the research station: genetic resources, breeding and variety studies of grapes, vegetable and subtropical fruit crops; development of a methodology for the creation and operation of intensive own-root plantations of grapes in the phylloxera infestation zone; obtaining environmentally safe products of grapes, vegetables and subtropical fruit crops. The main objectives of the research work are the creation of new genotypes of grapes, subtropical fruit and vegetable crops based on the mobilization of the potential of wild species, native and high-value introduced varieties with high productivity, product quality and resistance to abiotic and biotic stressors; improvement of the methodological base to accelerate the breeding process of grapes; identification of mechanisms for the realization of the genetic potential of indigenous and promising introduced grape varieties against the background of phylloxera infection, mechanisms for the formation of genetic and functional tolerance to the pest and scientific (biological) foundations for the creation of intensive own root plantations of grapes; identification of patterns of accumulation of dry matter and BAS in raw materials obtained from young broccoli plants and secondary products of grape and tomato processing depending on from varietal characteristics, stages of development, harvest period, processing methods; development of scientific and applied bases for obtaining environmentally safe raw materials for the production of functional food products and dietary supplements intended for the prevention of cardiovascular and oncological diseases. The research results expanded the base of genetic sources and methodological approaches for the creation of adaptive grape varieties in the changing climatic conditions of southern Russia, allowed to expand methodological approaches to the creation of root-related grape plantations and management of resistance to stressors, confirmed the fundamental possibility and effectiveness of hormonal management of the development of grape plants from the first year of life, as well as the quality of raw grapes, tomatoes and broccoli to create environmentally safe functional food products and dietary supplements, focused on the prevention of socially significant diseases.

Disaster accountability for the response/recovery stage and the role of hybrid organisations: The case of the anti-phylloxera consortia's reports

The historical literature appears limited in investigating the accountability and functioning of hybrid organisations engaged in countering natural disasters. Therefore, in the context of the phylloxera infestation disaster, this work aims to explore both the informative value and characters of some accountability documents and the role of anti-phylloxera consortia (public-private entities) during the response and recovery phases of the disaster. We apply content analysis through a thematic approach to two reports dating back to 1911 and 1912–1914, respectively, on the action of the anti-phylloxera consortia. On the one hand, this analysis highlights that the documents investigated have a relevant informative capacity, supporting knowledge dissemination and coordinated action. On the other hand, they account for the success of experimental vineyards in terms of agricultural parameters and re-gained productivity, but they do not present accounting data. Finally, the reports analysed show that public-private collaboration enacted by the consortia can be an effective tool for dealing with natural disasters and reducing their impact.

Canopy hedge pruning in pecan production differentially affects groups of arthropod pests and associated natural enemies

Controlling canopy growth and size through pruning techniques in perennial agroecosystems is often crucial to maximizing productivity. However, the implications of modifying canopy architecture for arthropod management are often overlooked. We studied the effects of hedge pruning on pests and natural enemies on mature pecan trees by assessing the abundance of: 1) leaf-dwelling aphids and mites, 2) visually detectable injuries caused by black pecan aphids [Melanocallis caryaefoliae (Davis)] and Phylloxera spp., 3) aphid parasitoids and parasitized hosts (aphid mummies), and 4) predatory mites. Additionally, we assessed the prevalence of entomopathogens that dwell on the orchard floor, under the trees. Hedge pruning decreased Phylloxera infestation but increased pressure from scorch mites and the yellow aphid complex. Black pecan aphid abundance responded inconsistently, but their damage was consistently reduced in hedged canopies. Predatory mites were only affected by hedging in the second year when higher populations were observed. Although parasitoid wasp abundance was not affected by hedging, more parasitized aphids (mummies) were observed in trees that did not receive pruning in the first year. Also, higher activity of entomopathogens was observed in soil cores collected under hedged trees in the first year but lower in the second. Taken together, the effects of hedge pruning pecan canopies were case-specific, and cannot be generalized across pests or natural enemies. Nevertheless, structural and environmental variation across seasons and within hedge pruning systems clearly have implications for crop protection in pecans and other perennial systems.

Winemaking terroir – the guideline for choosing of grape rootstocks for soils with different characteristics

The selection of rootstocks is one of the first and most important stages in the establishment of grape plantations under grafted conditions, which determines the productivity of rootstock-scion combinations and the further chain of design solutions: spatial placement of rows on the land plot, accompanying the production process of agronomic and agrochemical methods. Given the high importance of terroir factors for viticulture and winemaking, we were aware of the need to consider them in detail at this design stage. The aim was to create an algorithm for selecting varieties based on local terroir factors and apply it to the design of vineyards. Based on the analysis of literary sources and the agronomic experience of viticulture and winemaking specialists, we have identified key stress factors that in general, should be taken into account when selecting varieties of rootstocks. Based on the results of a comprehensive study of terroir and analytical diagnostics of soil samples taken on a land plot located in the Bakhchisaray district of the Republic of Crimea, local stress factors representing risks were clarified and prioritized neo-medially at the site of testing the landscape-adapted approach to the selection of rootstocks: carbonate condition, risk of phylloxera infestation, high content of fine fractions in granulometric composition, short-term droughts, risk of local overwatering, phosphorus deficiency. In total 20 the most common commercial varieties of rootstocks were considered for each selected soil area. The sample reduction scenario, based on the prioritization of the above stressors, reduced the number of varieties considered to three variants: 1103 Paulsen, 140 Ruggeri, and Fercal, which were scored against each other and considering the local terroir conditions of the plot, for further comparison in terms of market and logistics in making the final design decision.

Effects of grape phylloxera leaf infestation on grapevine growth and yield parameters in commercial vineyards: a pilot study

Grape phylloxera (Daktulosphaira vitifoliae) can infest both roots and leaves of Vitis species. In commercial vineyards planted with Vitis vinifera scions grafted on rootstocks, grape phylloxera infestation is generally limited to root feeding. Vineyards are, however, increasingly subjected to vineyard-wide foliar infestations that last throughout the growing season. While some vineyards are affected by the infestation pressure of external leaf-feeding populations, other annually affected V. vinifera vineyards do not have these in their vicinity. Much is known about the damage potential of grape phylloxera root feeding; however, data on how phylloxera leaf infestation affects V. vinifera grapevines in commercial vineyards are lacking. This study, therefore, aimed to assess whether grapevine growth and yield are affected due to leaf infestation as it occurred in three commercial vineyards in the study area. Treatments were based on phylloxera leaf infestation and additional defoliation. Single-leaf carbon acquisition was measured with gas exchange analyses on healthy and galled leaves. Pruning weight and internode length were measured to assess the effect of leaf infestation and the effect of plant growth and vigour on leaf gall outbreaks. Yield quantity and quality were measured, and grapes were vinified for sensory analyses. Furthermore, using enzymatic analyses, non-structural carbohydrates were analysed in perennial wood. A significant decrease in sugar content in grapes (10 %) and starch reserves in perennial wood (11 %) was found in the most heavily infested vineyard. Grape must of infested plants in another vineyard furthermore showed a significantly higher level of titratable acid (7.5 %). Significant infestation effects seen in one vineyard were not significant in the other two vineyards. No significant differences were seen for carbon acquisition, harvest quantity, wine sensory analysis, pruning weight or internode length. The overall effect of phylloxera leaf infestation in the studied vineyards was, therefore, marginal. Grapevine vigour did not differ between infested vines, insecticide-sprayed vines, and vines on which no leaf infestation outbreaks took place. By analysing phylloxera leaf infestation under field conditions, these preliminary results form a basis for future long-term field studies about phylloxera leaf feeding on Vitis vinifera within the context of other biotic and abiotic plant stresses.

Soil and Climate Geographic Information System Data-Derived Risk Mapping for Grape Phylloxera in Washington State.

Grape phylloxera (Daktulosphaira vitifoliae, syn. Viteus vitifoliae), a destructive root and foliar pest of grapevines, occurs in almost all viticulture regions worldwide. However, certain regions have remained “phylloxera free.” Until recently, this included Washington state (United States), where this insect is regulated as a quarantine pest by Washington State Department of Agriculture. In 2019, established phylloxera populations were discovered in Washington. Phylloxera is typically managed by using resistant or tolerant rootstocks. In Washington, most wine grapes are grown on their own roots of the susceptible species Vitis vinifera instead of grafted rootstock, and thus, are at high risk of vine death should they become infested with phylloxera. This article reports development of a phylloxera risk map for Washington state using geographical soil texture (sand content) and soil temperature data. Weighted averages of soil texture data (mapping year: 2016, depth: 0–100 cm) were obtained from United States Department of Agriculture-Natural Resource Conservation Service (USDA-NRCS) and soilgrids. Soil temperature data were obtained from over 200 weather stations of Washington State University’s AgWeatherNet network. Threshold-based classifications were performed in Quantum GIS software on the rasterized soil sand content and temperature independently to derive low, moderate, and high-risk areas, with risk defined as site suitability for optimal phylloxera development. The validation identified 22 out of 23 confirmed phylloxera-positive sites as “high risk,” and one site as “moderate risk” when considering soil sand content alone. Soil temperature data alone classified 10 sites as “high risk” and 13 sites as “low risk.” When soil sand content was combined with soil temperature (as a risk modifier), 10 sites were classified as “high risk,” 12 sites as “high-moderate risk” and one site as “moderate-low” risk. Ground-truth comparisons of confirmed positive sites for phylloxera agreed with past research suggesting that soil sand content is the dominant factor influencing phylloxera infestation. Pertinent risk assessment can be an important component for vineyard decision-making, including whether to use rootstocks in vineyard development or replant scenarios. It may also help to focus the initial scouting and identification efforts to sites and may be helpful when tracking and developing solutions for quarantine pests, such as phylloxera.

Effects of Foliar Phylloxera (Hemiptera: Phylloxeridae) Infestations on Wine Grape Photosynthesis, Yield, and Fruit Quality

Abstract Grape phylloxera, Daktulosphaira vitifoliae Fitch (Hemiptera: Phylloxeridae), is an important pest that forms galls on the foliage and roots of Vitis species. The effects of grape phylloxera on grape root have been studied extensively. This study investigated the effects of the foliar form of grape phylloxera, which is a persistent pest of North American native Vitis species and cold-hardy hybrid wine grapes between Vitis vinifera L. and Vitis riparia Michx. For a susceptible variety, ‘Frontenac’, in commercial Minnesota vineyards, there were reductions in cluster weight due to foliar phylloxera infestations in 2017 (one site; P = 0.05) and 2018 (three sites; nonsignificant). Reductions in cluster weight can be economically important to growers. For four grape varieties (susceptible and resistant) evaluated in the greenhouse, there were numerical reductions in photosynthetic rate and localized photosystem II efficiency in 1 of 2 yr. Resistant varieties had less of a reduction on conductance due to grape phylloxera infestation than susceptible varieties in 1 of 2 yr. The degree to which this occurs in resistant varieties may be related to the formation of fewer adaxial stomata; however, this hypothesis requires additional research. These results add important information to better understand how foliar phylloxera injury affects wine grape photosynthesis and yield. The results serve as a foundation for investigating variety-specific responses to foliar phylloxera through the use of advanced phenotyping technologies. This knowledge will lead to a better understanding of the effect of the pest on the diversity of cold-hardy grape varieties grown in the Midwestern United States.

Leaf vs. Whole-Plant Biotic Attack: Does Vine Physiological Response Change?

Phylloxera is one of the most invasive and widespread insects in viticulture. An increase in populations feeding on leaves and/or roots of formeR + Ly resistant grapevines has been observed, but information on leaf and whole plant phylloxera infestation effects is lacking. We monitored the water and carbon metabolism of vines (one rootstock x scion combination) inoculated with insects’ eggs on leaves (L) or both leaves and roots (R+L). Nonstructural carbohydrates (NSC) in infested and noninfested tissue of different organs and plant biomass were measured at the end of the experiment. At the peak of the biotic stress treatment, the plants reduced transpiration by about 30% compared to control, while photosynthesis remained unaffected. Lower soluble NSC were measured in infested than in the nearby noninfested tissue of both L and R+L groups, suggesting sugar consumption by the insect, while infested roots increased starch content by fivefold. NSC were depleted in noninfested roots of R+L plants as well, giving strength to the hypothesis of intense metabolites translocation in favor of the insect. A more distinct physiological depression in R+L vines compared to L was highlighted, even if the total biomass reduction was more marked in L plants. Our preliminary results suggest that the insect reprograms plant metabolism stimulating a more conservative water use, while competing with the host plant for carbon resources. Further studies should validate current results and quantify the NSC invested in the plant’s defense against the pest.

Candidate genes and SNPs associated with stomatal conductance under drought stress in Vitis

BackgroundUnderstanding the complexity of the vine plant’s response to water deficit represents a major challenge for sustainable winegrowing. Regulation of water use requires a coordinated action between scions and rootstocks on which cultivars are generally grafted to cope with phylloxera infestations. In this regard, a genome-wide association study (GWAS) approach was applied on an ‘ad hoc’ association mapping panel including different Vitis species, in order to dissect the genetic basis of transpiration-related traits and to identify genomic regions of grape rootstocks associated with drought tolerance mechanisms.The panel was genotyped with the GrapeReSeq Illumina 20 K SNP array and SSR markers, and infrared thermography was applied to estimate stomatal conductance values during progressive water deficit.ResultsIn the association panel the level of genetic diversity was substantially lower for SNPs loci (0.32) than for SSR (0.87). GWAS detected 24 significant marker-trait associations along the various stages of drought-stress experiment and 13 candidate genes with a feasible role in drought response were identified.Gene expression analysis proved that three of these genes (VIT_13s0019g03040, VIT_17s0000g08960, VIT_18s0001g15390) were actually induced by drought stress.Genetic variation of VIT_17s0000g08960 coding for a raffinose synthase was further investigated by resequencing the gene of 85 individuals since a SNP located in the region (chr17_10,497,222_C_T) was significantly associated with stomatal conductance.ConclusionsOur results represent a step forward towards the dissection of genetic basis that modulate the response to water deprivation in grape rootstocks. The knowledge derived from this study may be useful to exploit genotypic and phenotypic diversity in practical applications and to assist further investigations.

Gas exchange, biomass and non-structural carbohydrates dynamics in vines under combined drought and biotic stress

BackgroundIntensity of drought stress and pest attacks is forecasted to increase in the near future posing a serious threat to natural and agricultural ecosystems. Knowledge on potential effects of a combined abiotic-biotic stress on whole-plant physiology is lacking. We monitored the water status and carbon metabolism of a vine rootstock with or without scion subjected to water shortening and/or infestation with the sucking insect phylloxera (Daktulosphaira vitifoliae Fitch). We measured non-structural carbohydrates and biomass of different plant organs to assess the stress-induced responses at the root, stem, and leaf level. Effects of watering on root infestation were also addressed.ResultsHigher root infestation was observed in drought-stressed plants compared to well-watered. The drought had a significant impact on most of the measured functional traits. Phylloxera further influenced vines water and carbon metabolism and enforced the sink strength of the roots by stimulating photosynthates translocation. The insect induced carbon depletion, reprogramed vine development, while preventing biomass compensation. A synergic effect of biotic-abiotic stress could be detected in several physiological and morphological traits.ConclusionsOur results indicate that events of water shortage favour insects’ feeding damage and increase the abundance of root nodosities. Root phylloxera infestation imposes a considerable stress to the plants which might exacerbate the negative effects of drought.

A Novel Methodology for Improving Plant Pest Surveillance in Vineyards and Crops Using UAV-Based Hyperspectral and Spatial Data.

Recent advances in remote sensed imagery and geospatial image processing using unmanned aerial vehicles (UAVs) have enabled the rapid and ongoing development of monitoring tools for crop management and the detection/surveillance of insect pests. This paper describes a (UAV) remote sensing-based methodology to increase the efficiency of existing surveillance practices (human inspectors and insect traps) for detecting pest infestations (e.g., grape phylloxera in vineyards). The methodology uses a UAV integrated with advanced digital hyperspectral, multispectral, and RGB sensors. We implemented the methodology for the development of a predictive model for phylloxera detection. In this method, we explore the combination of airborne RGB, multispectral, and hyperspectral imagery with ground-based data at two separate time periods and under different levels of phylloxera infestation. We describe the technology used—the sensors, the UAV, and the flight operations—the processing workflow of the datasets from each imagery type, and the methods for combining multiple airborne with ground-based datasets. Finally, we present relevant results of correlation between the different processed datasets. The objective of this research is to develop a novel methodology for collecting, processing, analysing and integrating multispectral, hyperspectral, ground and spatial data to remote sense different variables in different applications, such as, in this case, plant pest surveillance. The development of such methodology would provide researchers, agronomists, and UAV practitioners reliable data collection protocols and methods to achieve faster processing techniques and integrate multiple sources of data in diverse remote sensing applications.

Land reform and conflict before the Civil War: landowner response to tenancy reform in 1930s Catalonia

AbstractThis article studies the impact of insecure property rights on the behaviour of owners of land before the Spanish Civil War. The theoretical literature on land reform argues that legal threats to the status quo determine agrarian organization, with owners selling land and moving to other asset classes or engaging in large‐scale substitution of sharecroppers and tenants with wage labourers. This study, which uses municipal data on tenant evictions in Catalonia in 1934–5, does not find that uncertainty over property rights in the 1930s meant that owners tried to substitute tenants with wage labourers, especially in the case of the controversial rabassa morta contracts on vineyards. Here it is argued that after 40 years of organizational adjustment to shocks related to phylloxera infestations, legal changes, urbanization, and changes in relative prices, by the 1930s the margin for adjustment was small.

Vergleichende Untersuchung der bodenbewohnenden Nematodenfauna von mit der Wurzelreblaus ( Viteus vitifoliae Fitch) befallenen Weinreben ( Vitis spp.)

Comparative study ofthe soil-living nematofauna associated with vine ( Vitis spp.) infested with phylloxera ( Viteus vitifoliae Fitch) The diversity and the community structure of nematodes, and the correlation between the occurrence of nematodes and the infestation of grapevines ( Vitis spp.) with grape phylloxera ( Viteus vitifoliae ) were studied. Grapevines ungrafted and grafted to different rootstocks were planted and samples of roots and soil were collected at 7 sites in the Austrian vine growing regions Weinviertel, Neusiedlersee, Sudburgenland, and Sudoststeiermark. The formation of nodosities on rootlets and the nematode fauna were examined. A total of 58 nematode genera (37 families) were found to be associated with grapevines. Mean nematode abundance in the 7 vineyards ranged from 342 to 444 individuals per 100 g soil. Diversity indices, mean evenness, Maturity Index (MI), and Plant Parasite Index (PPI) were nearly identical among sites and no significant differences were found between phylloxera-infested and non-infested rootstocks. Looking at the trophic structure given by feeding types (bacteriovores, carnivores, omnivores, plant parasites, fungivores) the plant parasitic nematodes were the dominant feeding group; they were detected in all vineyards. Helicotylenchus digonicus, Helicotylenchus vulgaris, Paratylenchus spp., Pratylenchus spp., Mesocriconema xenoplax, Tylenchorhynchus dubius and Xiphinema vuittenezi were the most frequent plant parasitic nematodes. Helicotylenchus was the only nematode genera correlated with phylloxera infestation. The genera Helicotylenchus showed significantly higher abundances at rootstocks infested with phylloxera and at some sites its abundance was up to 680 individuals per 100 g soil.

NUCLEAR MAGNETIC RESONANCE METABOLIC PROFILING OF LEAVES FROM VITIS VINIFERA INFESTED WITH ROOT-FEEDING GRAPE PHYLLOXERA (DAKTULOSPHAIRA VITIFOLIAE FITCH) UNDER FIELD CONDITIONS

Partial least squares discriminant analysis (PLS-DA) models developed from 1 H NMR spectra acquired from aqueous extracts Vitis vinifera leaf material successfully discriminated between grape phylloxera-infested and uninfested grapevines under field conditions. Loadings plots demonstrated differences in the metabolic profile between treatments in the aromatic, carbohydrate and amino acid fingerprint regions of the 1 H NMR spectrum. Resonances consistent with sucrose and the phenolic moeities caffeic acid and quercetin were up-regulated in infested grapevines, while α- and β- anomers of glucose and leucine were down regulated in infested grapevines. The detection of putative quercetin resonances corroborated with the results from a previous LC/MS study. This may lead to its inclusion as a potential candidate biomarker of grape phylloxera infestation once further validation trials have been undertaken.

Scientific Opinion on the risk to plant health posed by Daktulosphaira vitifoliae (Fitch) in the EU territory, with the identification and evaluation of risk reduction options

The Panel on Plant Health conducted a pest risk assessment for the grapevine insect pest, Daktulosphaira vitifoliae (an aphid species commonly known as phylloxera), in the European Union, identified risk reduction options and evaluated the effectiveness of the phytosanitary measures listed in Council Directive 2000/29/EC. Entry was assessed as potentially very likely for plants intended for planting (although the pathway is closed by Article 15 of Annex III) and very unlikely for fruit for consumption because transport and transfer would be very difficult, even though phylloxera has a moderate likelihood of association with the pathway. Establishment is very likely as the pest is already very widespread in the risk assessment area, occurring almost everywhere Vitis plants are present. Successful eradication is very unlikely and small populations can persist undetected in the soil. Spread within the EU is considered to be very likely because there are no effective barriers, it can disperse up to a few kilometres aided by the wind and it can readily be moved long distances with planting material. Grafting with resistant rootstocks throughout the EU ensures that the production of fruit and plants for planting is rarely affected by phylloxera infestations and, if so, only at a limited level. The Panel considers that the IIAII measures for D. vitifoliae do not assist in preventing entry and are ineffective in preventing spread because detection is so difficult. Restricting movements of plants for planting to cuttings grafted on resistant rootstocks, in combination with treatments (e.g. particularly fungicides and hot water treatments), was found to be the most effective risk reduction option. Limitations in the Cyprus protected zone regulations were identified.

Gene expression profiling of rootstock ‘140Ru’ and Vitis vinifera L. cv. ‘Crimson Seedless’ grape roots infected with grape phylloxera

Grape phylloxera (Daktulosphaira vitifolia Fitch) is the most devastating pest of grape. Information concerning the molecular basis of grape root–phylloxera interactions will enhance the future development of effective management tools against this pest. In this study, changes in gene transcript abundance in grape roots in response to phylloxera infestation were measured using the Affymetrix Vitis vinifera Genome Array. Two genetically related grape roots, rootstock ‘140Ru’ (potted ‘140Ru’, which forms nodosities but no tuberosities in response to phylloxera infestation) and V. vinifera L. cv. ‘Crimson Seedless’ (which forms both nodosities and tuberosities) were utilized in the current study. Pairwise comparisons followed by false discovery rate analysis indicated that the expression levels of 1,204 transcripts changed significantly in ‘140Ru’; 599 increased and 625 decreased. However, in ‘Crimson Seedless’, the expression of 799 transcripts changed significantly, including 305 that increased and 494 that decreased. Comparative analysis of these transcripts indicated that a total of 155 transcripts were common to both resistance and susceptible responses. In this set, the levels of 48 transcripts increased in ‘140Ru’ but decreased in ‘Crimson Seedless’. Quantitative real-time RT-PCR confirmed the results of the microarray analysis. Since nodosities potentially function as nutrient reservoirs, probe sets corresponding to the categories of energy metabolism and carbohydrate metabolism were more commonly induced in ‘Crimson Seedless’. Defense responses of ‘140Ru’ to phylloxera attack were detected. Probe sets that were uniquely induced in ‘140Ru’ are associated with the biosynthesis of secondary metabolites. This study may aid in the identification of genes involved in plant defenses against grape phylloxera.

EARLY DETECTION OF GRAPE PHYLLOXERA (DAKTULOSPHAIRA VITIFOLIAE FITCH) INFESTATION THROUGH IDENTIFICATION OF CHEMICAL BIOMARKERS

Principle components analysis (PCA) was used to assess the presence of phylloxera associated biomarker compounds in G1 phylloxera infested Vitis vinifera L. vines in the Yarra Valley, Victoria. High Performance Liquid Chromatography (HPLC) analysis showed strongly upregulated flavonoid secondary metabolites in 80% methanol:water vine leaf extracts with mass spectroscopy (MS) analysis yielding the identification of four flavonoid compounds: isorhamnetin glycoside, rutin, kaempherol glycoside and quercetin glycoside. Flavanoids and other phenolics are a common class of bioactive compounds that form part of the endogenous or induced biochemical defence mechanisms employed by plants to counter infectious pathogens and insect attack, among other functions. The specificity of these flavonoid compounds to phylloxera infestation is currently being validated through field and glasshouse-based trials against nutrient and water stress. Successful correlation of these compounds to phylloxera infestation would provide a platform for laboratory-based early detection, leading to more timely advice to viticulturalists, more rapid instigation of quarantine protocols and a great reduction in losses associated with late detections of phylloxera infestations.

A STEPWISE ASSESSMENT OF DAKTULOSPHAIRA VITIFOLIAE INFESTED GRAPEVINES IN A VIENNESE VINEYARD SITE

Daktulosphaira vitifoliae Fitch, the grape phylloxera, occurs in high numbers on the leaves of leaf-forming rootstocks in a Viennese vineyard site. Later in the season the appearance of leaf-galls on Vitis vinifera was also observed in commercial vineyards. Assessing five different areas in a Viennese vineyard site the distribution of the phylloxera infestation was determined in eight categories. Methods • Five different areas (Neustift + Hackenberg (79,5 ha), Nussberg (144 ha), Wilhelminenstift + Galizienstift (14,1 ha) in the northwest of Vienna were examined for phylloxera infestation. • A total of 34 locations with leaf-forming rootstocks (referred to as “Drische”) were observed over the vegetation period in 2010. • Data was evaluated in two weeks intervals from 26.05 till 15.09. Results The first leaf-galls were observed in May, reaching the maximum potential during August - September mainly on sunny sites that were sheltered from the wind. First leaf-galls were observed in vine yards planted with V. vinifera in mid-July close to „Drischen“ in Neustift, Hackenberg and Nussberg.

The volatile metabolome of grapevine roots: first insights into the metabolic response upon phylloxera attack.

Many plant species respond to herbivore attack by an increased formation of volatile organic compounds. In this preliminary study we analysed the volatile metabolome of grapevine roots [Teleki 5C (Vitis berlandieri Planch. × Vitis riparia Michx.)] with the aim to gain insight into the interaction between phylloxera (Daktulosphaira vitifoliae Fitch; Hemiptera: Phylloxeridae) and grapevine roots. In the first part of the study, headspace solid phase microextraction (HS-SPME) coupled to gas chromatography – mass spectrometry (GC–MS) was used to detect and identify volatile metabolites in uninfested and phylloxera-infested root tips of the grapevine rootstock Teleki 5C. Based on the comparison of deconvoluted mass spectra with spectra databases as well as experimentally derived retention indices with literature values, 38 metabolites were identified, which belong to the major classes of plant volatiles including C6-compounds, terpenes (including modified terpenes), aromatic compounds, alcohols and n-alkanes. Based on these identified metabolites, changes in root volatiles were investigated and resulted in metabolite profiles caused by phylloxera infestation. Our preliminary data indicate that defence related pathways such as the mevalonate and/or alternative isopentenyl pyrophosphate-, the lipoxygenase- (LOX) as well as the phenylpropanoid pathway are affected in root galls as a response to phylloxera attack.