Astrid Forneck

Grape phylloxera (Daktulosphaira vitifoliae Fitch) is a major global pest of cultivated grapevine. Armenia presents an unusual viticultural system, with 85-90% of vineyards remaining own-rooted despite the established presence of phylloxera. We investigated the genetic diversity and population structure of 370 root-feeding individuals collected from three localities in the Ararat Valley and Tavush Province using seven polymorphic simple sequence repeat markers. The seven loci yielded 48 alleles, with mean expected and observed heterozygosities of 0.570 and 0.933, re-spectively. Analysis of molecular variance revealed significant regional differentiation (Fst = 0.127, P = 0.001), driven primarily by differentiation between Tavush and the Ararat Valley popu-lations. The 370 individuals comprised 55 multilocus genotypes (MLGs), with two dominant MLGs represented by 171 and 116 individuals, together accounting for 77.6% of the sample. A population-aware, clone-corrected analysis of 59 MLG-by-population observations confirmed the same regional pattern and yielded stronger differentiation (Fst = 0.163, P = 0.001). Concordant separation of Tavush from the Ararat Valley was observed in principal coordinates analysis and discriminant analysis of principal components. The predominance of repeated MLGs is consistent with substantial clonal amplification. This study provides the first molecular baseline for D. vitifoliae in Armenia and establishes a foundation for monitoring genotype persistence, dispersal, and regional differentiation.

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.

Drought is becoming more frequent and severe in numerous wine‐growing regions. Nevertheless, limited research has examined the legacy of recurrent droughts, focusing on leaf physiology and anatomy over consecutive seasons. We investigated drought legacies (after 2 years of drought exposure) in potted grapevines, focusing on stomatal behaviour under well‐watered conditions during the third year. Vines were subjected for two consecutive years to short‐ (SD) or long‐term (LD) seasonal droughts, or well‐watered conditions (WW). In the third year, all plants were grown without water limitation. Water potential and gas exchange were monitored throughout the three seasons, while leaf morpho‐anatomical traits were measured at the end of the third year. During droughts (1st and 2nd year), stem water potential of SD and LD plants fell below −1.1 MPa, with a consequent 75% reduction in stomatal conductance ( g _s ) compared to WW. In the 3rd year, when all vines were daily irrigated to soil capacity (midday stem water potential ~ −0.3 MPa), 45% lower values of g _s were observed in the ex‐LD group compared to both ex‐SD and ex‐WW. Reduced midrib vessel diameter, lower leaf theoretical hydraulic conductivity, and smaller stomata were measured in ex‐LD leaves compared to ex‐SD and ex‐WW, likely contributing to the reduced gas exchange. Our findings suggest that grapevines exposed to drought may adopt a more water‐conserving strategy in subsequent seasons, irrespective of current soil water availability, with the degree of change influenced by the intensity and duration of past drought events.

Grapevine berry shrivel, a ripening disorder, causes significant economic losses in the worldwide wine and table grape industries. An early interruption in ripening leads to this disorder, resulting in shriveling and reduced sugar accumulation affecting yield and fruit quality. Loss of sink strength associated with berry mesocarp cell death is an early symptom of this disorder; however, potential internal or external triggers are yet to be explored. No pathogens have been identified that might cause the ripening syndrome. Understanding the underlying causes and mechanisms contributing to berry shrivel is crucial for developing effective mitigation strategies and finding solutions for other ripening disorders associated with climacteric and non-climacteric fruits. This review discusses alterations in the fruit ripening mechanism induced by berry shrivel disorder, focusing primarily on sugar transport and metabolism, cell wall modification and cell death, and changes in the phytohormone profile. The essential open questions are highlighted and analyzed, thus identifying the critical knowledge gaps and key challenges for future research.

Ailanthus altissima is among the most invasive woody species worldwide, outcompeting native trees. The fungus Verticillium nonalfalfae (VN) is promising for A. altissima biocontrol, and its effects on the host have been studied via visual assessment in a range of host species. However, little research was performed to address fungal effects on the physiological processes of non-target woody plants. We investigated the occurrence of visual and non-visually recognisable perturbations of VN infection on potted vines to evaluate the potential risks of the biocontrol pathogen on viticulture. Eighteen four-years-old Vitis vinifera (cultivar Grüner Veltliner grafted on Kober 5BB) potted plants were inoculated with VN conidial suspension of the fungus (F), while nine plants were treated with sterile water (C, control). Disease symptoms and physiological parameters were monitored throughout the experiment (seven evaluation dates), while leaf water potential, leaf mass per area (LMA) and biomass were measured at the end of the study when plant tissue was sampled for re-isolation of the fungus. In our trial, inoculations with VN induced characteristic wilting symptoms only in Ailanthus (used as side control of the inoculum), while vines remained asymptomatic, thus indicating a high degree of host specificity of VN. Limited or no impact was detected on the physiology of the non-target V. vinifera. Furthermore, the LMA and biomass measured in the two experimental groups were not different. Although fungal colonisation induced vascular discolouration in both species, the fungus could only be re-isolated from dying Ailanthus but not from vine tissue. Results suggest that V. vinifera cv Grüner Veltliner is resistant to the applied VN isolate. However, the susceptibility and physiology of additional grapevine cultivars, as well as other native woody species to VN, should be studied before promoting large-scale use of the biocontrol agent.

Viticulture is a perennial cropping system that provides large inter-row space as a non-crop habitat for a range of different taxa. Extensive vegetation management has been shown to increase biodiversity and ecosystem service provision in vineyards. Important soil ecosystem services are decomposition, nutrient cycling, and pest regulation provided by the mesofauna (e.g., Acari and Collembola). However, studies investigating the effects of inter-row management on soil mesofauna are scarce. We studied the effect of inter-row management intensity (complete vegetation cover, alternating vegetation cover, and bare ground) and local pedoclimatic conditions on Acari and Collembola in nine Austrian vineyards. Our results showed that the clay content of the soil was the most important factor and increased the abundances of both analyzed taxa. Complete and alternating vegetation cover increased their abundance in comparison to bare ground management. Higher soil respiration slightly contributed to higher abundances of those two taxa in both years. In conclusion, besides the positive effects of the clay content in the soil, complete and alternating vegetation cover are feasible management practices for increasing soil mesofauna in vineyards.

We evaluated the chemical composition and antioxidant activity of 30 red wines from Austria (cv. Cabernet-Sauvignon, Blaufraenkisch and Zweigelt) and 20 wines from Montenegro (cv. Cabernet-Sauvignon and Vranac) from three consecutive vintages: 2014, 2015 and 2016. We determined spectrophotometrically the contents of total phenol (TP), total anthocyanin (TA) and low- and high-molecular-weight proanthocyanidins (LMP and HMP respectively). We identified and quantified 18 phenolic compounds (hydroxycinnamic acids, hydroxybenzoic acids, stilbenes and flavan-3-ols) by high-performance liquid chromatography. In addition, we used Fourier-transform infrared spectroscopy for chemical analyses of the main wine parameters. Austrian autochthonous wines exhibited a similar chemical composition (alcohol 12.4 vol%, pH 3.38). Blaufraenkisch wines showed higher TP, HMP and LMP than Zweigelt wines; however, TA content was similar. Blaufraenkisch wines also showed higher phenolic acid, flavan-3-ol and stilbene contents than Zweigelt wines. Montenegrin autochthonous Vranac wines showed a typical chemical composition (alcohol 13.0 vol%, pH 3.42), and medium to high levels of phenols: TP, HMP, LMP, TA, HCA and flavan-3-ols. On the other hand, they showed a moderate stilbene content. Cabernet-Sauvignon wines from Austria and Montenegro exhibited some similarities in phenolic composition: TP, HMP, LMP and TA. There were notable variations in the phenolic acid and flavan-3-ol contents, especially the stilbene content, which was much higher in the Austrian wines than in the Montenegrin wines. These findings evidence an important impact of climatic conditions on these compounds. The antioxidant activity in all investigated wines was high and correlated strongly with TP, total phenol index, HMP and LMP in wines. The vintage influenced the chemical composition and content of all examined phenolic groups, except flavan-3-ols. Wines from the vintage with the best maturity (2015) contained the highest content of spectrophotometrically determined phenolic compounds and lowest level of phenolic acids and stilbenes. Principle component analysis showed that wines were mainly discriminated by variety and origin but not by vintage.

Pioneering grapevines also referred to as “PIWIs” (after the German expression “pilzwiderstandsfähig” = fungus resistant), represent an interesting alternative to classic cultivars in several wine regions. Their resistance to some fungal diseases places them among the potential solutions for sustainability, especially under organic production systems. However, little is known about their response to abiotic stressors, such as water stress under drought conditions. Here we studied the response of three PIWI cultivars (Donauriesling, Muscaris, Souvignier gris, and Riesling or Grüner Veltliner Vitis vinifera cultivars as comparison; all plants without fruit) to drought under semi-controlled conditions over two consecutive seasons. While in season 2020, we imposed a single dry-down and re-watering cycle inside a glasshouse, during season 2021, we subjected the vines to three cycles of dehydration and re-watering under field conditions with the aid of a rain shelter. Along the experiments, we monitored leaf gas exchange and water potential during soil dehydration and characterised leaf area development and some key leaf hydraulic traits. Despite different conditions in our two study seasons, we found connective significances in some key parameters. Under well-watered conditions, Souvignier gris had the highest rates of stomatal conductance, whereas Muscaris exhibited the most conservative water use behaviour. When under drought, Souvignier gris showed an apparent less tight stomatal control than the other PIWIs in coordination with a lower (more negative) osmotic potential and turgor loss point. Our results suggest that Muscaris (and Donauriesling showed similar behaviour) might be more suitable for non-irrigated conditions than Souvignier gris. However, further research on berry composition and open field is needed to upscale our results and address the water management of PIWI vineyards.

In vineyards, the under-vine area is managed to control vegetation growth and to reduce the competing effect of growing plants on vines and fruit development. Applied under-vine management methods are the application of herbicides, soil tillage or the growth of spontaneous vegetation or cover crops. These methods affect pedo-climatic conditions differentially as well as the soil biota and have, therefore, consequences on soil functions and ecosystem services. In the presented case study, the effects of five under-vine management methods on the activity of soil hydrolytic enzymes, the soil water content, vine photosynthetic activity, shoot pruning weight, grape yield and quality are investigated in a vineyard in Lower Austria over three consecutive seasons. Thereby, we hypothesise that a permanent under-vine vegetation cover, either mowed or without mowing, supports the soil microbial communities and soil functions in a way to enhance water and nutrients availability for vines which partly compensates for the competition of the growing vegetation. Our results confirm effects on the soil water balance, more specifically, a reduced soil water content in 11 -20 cm soil depths induced by a permanent vegetation cover as compared to herbicide application or soil tillage. Further consequences of permanent vegetation below vines were lower shoot pruning weights and lower berry weights, while total soluble solids and titratable acidity were not affected. The vine's photosynthetic activity, as well as the soil water content, were partly affected by treatments dependent on the precipitation ahead of the measurement. In parallel, the soil microbial activity was significantly enhanced by a permanent vegetation cover below the vines as compared to herbicide application, a trend which increased with the years of the project. In conclusion, permanent under-vine vegetation strongly promoted soil microbial activity without strong effects on shoot pruning weight, grape yield and quality. In the next step, a functional proof is necessary to characterise the interaction between soil microbial activity, soil water balance and vine nutrition and water status by using sensors for continuous measurements.