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The dynamic fluctuations in autumn temperatures, particularly the marked diurnal variations and the subsequent precipitous drops are key and a pivotal role in viticulture, as they critically influence the acclimation process of grapevines to cold, thereby directly impacting their survival and productivity in cold-climate regions. In this comprehensive study, we investigated the cold hardiness of four grapevine cultivars: 'Itasca', 'Frontenac', 'La Crescent', and 'Marquette', focusing on how these cultivars and their individual buds (1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, and 9th) respond to fluctuating weather and low temperatures typical of autumn [-1.1℃ (30°F) -9.4℃ (15°F) and -17.8℃ (0°F)]. Our results illuminated the striking variability in cold hardiness that was manifest not only among the different cultivars but also within individual buds on the same vine, underscoring the critical influence of bud position on a vine for cold hardiness. 'Frontenac' showed greater cold hardiness at critical temperatures at which 10%, and 50% of the dormant buds were lethally affected by cold (LT10 and LT50) compared to 'Itasca' and 'La Crescent', with 'Marquette' exhibiting intermediate values. However, in cultivars such as 'Itasca' and 'Marquette', certain buds demonstrated a pronounced hardiness when faced with colder temperatures, while others exhibited a heightened sensitivity, thereby revealing a nuanced interplay between bud position and a vine's ability to withstand cold stress. Our study revealed a notable divergence from traditional viticulture understanding; apical buds demonstrated greater cold hardiness than basal buds and opened new paths for research into grapevine physiology. Our results also indicated a significant trend wherein older vines across all studied cultivars displayed enhanced cold hardiness, particularly pronounced at the critical LT50 and the critical temperature at which 90% of the dormant buds were lethally affected by cold (LT90) thresholds, in comparison to younger vines. Moreover, our findings shed light on the impact of autumn's diurnal temperature variations and the subsequent drop in temperatures on vine cold hardiness, thus highlighted the complex interplay between environmental temperature dynamics and dormant bud hardiness. In conclusion, our study showed that the cold damage observed in grapevines in North Dakota was not a result of extreme temperature fluctuations in the fall. This was confirmed by testing the vines after they had reached various threshold temperatures through differential thermal analysis (DTA) and optical differential nucleation and expansion analysis (ODNEAL) methodologies, particularly before the onset of severe pre-winter cold conditions. These comprehensive findings highlighted the complexity of the vine's response to climatic conditions and viticultural management, pointing to the need for specific strategies in vineyard management and cultivar selection to optimize bud hardiness and productivity in the face of various environmental challenges, especially in cold climate viticulture. [ABSTRACT FROM AUTHOR]

'Flavescence dorée' (FD) is a quarantine grapevine disease associated with FD phytoplasmas (FDp). In Switzerland, FD was first reported in 2004 in the southern part of the Canton Ticino, from where, within a few years, it spread to nearly the entire vineyard area of the Southern Alps, despite the mandatory control measures. The aim of this study was to assess the possible role of gone‐wild grapevines (GWGVs) in forests resulting from early abandoned vineyards as a habitat for the main FDp vector, Scaphoideus titanus, and for the best alternative vector candidate, Orientus ishidae, as well as an FDp inoculum reservoir in Southern Switzerland. Leaf samples were collected in 20 plots and tested for the presence of FDp. Moreover, fifteen of these plots were monitored with yellow sticky traps to determine the presence and infection status of insect vectors. Finally, a hatching experiment under controlled conditions was conducted to investigate the possible oviposition activity by FDp vectors, using wood collected from GWGVs present in 11 forest sites in the surroundings of cultivated vineyards. GWGVs in forests were confirmed to act as an FDp reservoir and to represent a suitable habitat for FDp vectors (in particular, for S. titanus). Abandoned vineyards should be included in the FD management strategy and their systematic rogueing should be applied as soon as possible and in particular before the transition from vineyard to forest occurs, in order to avoid the survival of S. titanus and the establishment of inoculum in uncontrolled landscape compartments. [ABSTRACT FROM AUTHOR]

Intensive breeding programmes have been carried out to obtain high‐quality seedless grape cultivars. Seedless grape cultivars were used as pollinizer parents, but the number of hybrid seeds and the viability of the seed obtained could differ greatly. In this study, carried out over 3 years, the results obtained from crossing with some pollinizer cultivars belonging to different Vitis species were compared. Maternal cultivars that do not need emasculation (male sterile) and emasculated cultivars were also compared. Evaluations were based on the total number of hybrid seeds and the proportion of viable seeds. In addition, the effects of various treatments on the rates of germination of the hybrid seed were compared. Although the female parents (with female flower structure) produced more seed than did hermaphrodite mothers in 2019, different results were obtained in cross‐breeding studies in 2018 and 2020. Cold stratification was very effective in increasing germination by breaking dormancy of the hybrid seed. In addition, after treatment of cold moist storage (cold stratification), keeping the seed in distilled water overnight before planting increased germination. Although large numbers of seeds were produced by the genotype 86/1 and the cultivar 'Beyaz Çavuş', both of which do not require emasculation, many of these seeds did not germinate. Crosses with the cultivar 'Red Globe' as the maternal parent produced large numbers of viable seeds and high germination rates. [ABSTRACT FROM AUTHOR]

Asian grapevine leaf rust (AGLR) causes severe crop losses in Brazilian viticulture, mainly in latitudes <25°S. The purpose of this study was to identify the pathogen(s) involved with AGLR in Brazil, based on phylogenetic and morphological analysis and pathogenicity tests. In total, 56 monouredinial isolates from six Brazilian states were identified using the internal transcribed spacer 2 and the large subunit rRNA gene D1/D2 regions. All 50 isolates from the south‐central region were classified as Neophysopella tropicalis, and the other six isolates from the north‐east region as Neophysopella meliosmae‐myrianthae. This result provides evidence that two pathogen introductions from different sources may have occurred in the country. For both species, paraphyses were cylindrical, incurved, aseptate, and hyaline, while urediniospores were short‐pedicellate, obovoid or obovoid‐ellipsoid, with the wall colourless or pale yellowish, evenly echinulate. Representative isolates from both species caused typical AGLR symptoms on Vitis vinifera 'Merlot' and V. labrusca 'Niagara Rosada'. Overall, regardless of the Neophysopella species, isolates caused similar leaf disease severities. Higher disease severity was observed in Niagara Rosada (average of 40.3% of diseased leaf area) compared to Merlot (20.5%). This study reports, for the first time, the characterization of Neophysopella species associated with AGLR in Brazil. [ABSTRACT FROM AUTHOR]

Black foot disease of grapevines is a major economic issue for the viticulture industry worldwide. The disease is mainly associated with a complex of pathogen species within the genera Dactylonectria and Ilyonectria. The susceptibility of six grapevine rootstock cultivars to black foot disease under field conditions was assessed. Callused rootstocks of 101-14, 5C, 420A, Riparia Gloire, Schwarzmann and 3309C were planted into soil containing low natural pathogen populations or inoculated with isolates representing the species diversity in New Zealand. Disease incidence, disease severity and dry weight accumulation were assessed after 8 months of growth. Root and shoot dry weights were not significantly affected by inoculation treatment, but differed among rootstock cultivars, with cultivar 420A having the lowest root and shoot dry weight, cultivar 3309C having the largest shoot dry weight and cultivar 5C the largest root dry weight. The relative susceptibility of rootstocks differed significantly depending on whether they were grown under low natural inoculum pressure or a higher pressure in artificially inoculated soil. Schwarzmann and Riparia Gloire rootstock cultivars were the least susceptible under natural low inoculum pressure, but were the most susceptible in inoculated soil. In contrast, 5C was one of the most susceptible under low inoculum levels but was the least susceptible under high pathogen pressure. The result of the study indicate that black foot pathogen inoculum levels in soil affect the relative susceptibility of grapevine rootstocks to infection, and may have implications for the selection of rootstocks for planting. [ABSTRACT FROM AUTHOR]

Background: Grafting is widely used in horticulture and rootstocks are known to modify scion growth and adaptation to soil conditions. However, the role of scion genotype in regulating rootstock development and functioning has remained largely unexplored. In this study, reciprocal grafts of two grapevine genotypes were produced as well as the corresponding homo-graft controls. These plants were subjected to a low phosphate (LP) treatment and transcriptome profiling by RNA sequencing was done on root samples collected 27 h after the onset of the LP treatment. Results: A set of transcripts responsive to the LP treatment in all scion/rootstock combinations was identified. Gene expression patterns associated with genetic variation in response to LP were identified by comparing the response of the two homo-grafts. In addition, the scion was shown to modify root transcriptome responses to LP in a rootstock dependent manner. A weighted gene co-expression network analysis identified modules of correlated genes; the analysis of the association of these modules with the phosphate treatment, and the scion and rootstock genotype identified potential hub genes. Conclusions: This study provides insights into the response of grafted grapevine to phosphate supply and identifies potential shoot-to-root signals that could vary between different grapevine genotypes. [ABSTRACT FROM AUTHOR]

Inflorescence architecture provides the scaffold on which flowers and fruits develop, and consequently is a primary trait under investigation in many crop systems. Yet the challenge remains to analyse these complex 3D branching structures with appropriate tools. High information content datasets are required to represent the actual structure and facilitate full analysis of both the geometric and the topological features relevant to phenotypic variation in order to clarify evolutionary and developmental inflorescence patterns. We combined advanced imaging (X-ray tomography) and computational approaches (topological and geometric data analysis and structural simulations) to comprehensively characterize grapevine inflorescence architecture (the rachis and all branches without berries) among 10 wild Vitis species. Clustering and correlation analyses revealed unexpected relationships, for example pedicel branch angles were largely independent of other traits. We identified multivariate traits that typified species, which allowed us to classify species with 78.3% accuracy, versus 10% by chance. Twelve traits had strong signals across phylogenetic clades, providing insight into the evolution of inflorescence architecture. We provide an advanced framework to quantify 3D inflorescence and other branched plant structures that can be used to tease apart subtle, heritable features for a better understanding of genetic and environmental effects on plant phenotypes. [ABSTRACT FROM AUTHOR]

Overcoming host defensive traits is a prerequisite to establish compatible plant-parasite interactions. Following parasite perception, jasmonic (JA) and salicylic acid (SA) signalling pathways mediate biotic stress signals resulting in the activation of host defence responses. Piercing-sucking grape phylloxera (Daktulosphaira vitifoliae) infests Vitis spp. by the formation of organoid root galls. This study aims to investigate whether host defensive SA/JA signalling pathways are affected during D. vitifoliae infestation. We hypothesize that the JA signalling pathway is induced during larval probing (14 hai). Compatible root gall formation (24 hai − 14 dai) involves the reduction of the JA, but the induction of the SA signaling pathway. T5C (V. berlandieri x V. riparia) cuttings are infested with a D. vitifoliae single founder lineage (biotype C). Phytohormone quantification (HPLC-MS) and transcriptional alterations of JA/SA marker genes (qRT-PCR) are determined in root tissues from larval probing (14 hai) until gall formation (>14 dai). Non-infested root tips are considered controls. Our results show a significant induction of all analysed JA marker genes during insect probing (14 hai), but their significant reduction during early gall formation (24 hai). Following gall formation (5–14 dai) SA and JA-Ile increase. However, only the analysed SA marker genes are induced, whereas JA marker gene expression levels are significantly reduced. Based on this data we conclude that the observed suppression of the JA signalling pathway might represent an important step for the compatible D. vitifoliae – Vitis spp. root interaction. We discuss whether the induced SA defences protect nutritive root galls against soil microbes. • D. vitifoliae probing induces the JA signaling pathway on Vitis spp. roots. • Subsequent root gall formation involves the transcriptional suppression of the JA, but the induction of the SA signaling. • Induced SA defence responses might protect nutritive root gall tissue against soil microbes. [ABSTRACT FROM AUTHOR]

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Plant growth and reproductivity of grape cv. 'Italia' subjected to two different irrigation levels in controlled glasshouse were investigated over 2 years. Initially, two years old vines were grafted on 5 BB (V. berlandieri Planch.⨰V. riparia Michx.), 99 R (V. berlandieri Planch.⨰V. rupestris Scheele) rootstocks or on its own root system in 40 L pots. During the cultivation, half of the vines of each experimental group were Fully Irrigated (FI: 100% of field capacity) while the others were subjected to continuous Deficit Irrigation (DI: 40% of field capacity). During the study, significant negative effects of DI on plant vegetative development and physiology were observed. The lignified shoot length of vine on 5 BB rootstock decreased by 29.1% under DI as compared to growth under FI. On the other hand, the vine with 99 R rootstock decreased by 18.2% under DI as compared to lignified shoot growth under FI, while a 20.1% decrease occurred for own root (DI vs. FI). Also, DI regime resulted in slight decreases in P, K, and Ca status of leaves, while Zn and Cu concentrations were significantly higher in the vines subjected to DI. DI resulted in reduced cluster weight and vine yield in varying degrees with respect to rootstock usage. Under DI condition, the vines on 99 R yielded better than those on 5 BB, but vines on on 5 BB reacted adversely to DI. Considering the overall findings, grapevines cv. 'Italia' on 99 R exhibited higher drought tolerance than 5 BB. Rootstocks had slight impairing effects on physiological traits, yield, and mineral acquisition of grapevine cv. 'Italia' as compared to own-rooted. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Nowadays the value of human economic activities is no longer measured only in terms of efficiency and profit, but also in terms of sustainability. When it comes to agriculture, one of the biggest areas of improvement involves the decrease of chemicals. Although vineyards cover less than 5% of agricultural land in Europe, viticulture is responsible for the use of more than 60% of all fungicides. The exploitation of grapevine varieties resistant to mildews is an efficient strategy already implemented in integrated/organic farming to reduce treatments. However, from the beginning of this century, European viticulture has been threatened by severe outbreaks of black rot (BR), an emergent and destructive disease caused by the ascomycete Phyllosticta ampelicida (sexual morph Guignardia bidwellii). These events introduced the urgent need for the introgression of BR resistance in mildewtolerant genotypes. For this purpose, a set of parental lines and breeding selections of the Fondazione Edmund Mach has been screened for BR resistance in a growing chamber with in vivo produced spores using an optimized artificial infection protocol. Given the good performance of 'Merzling' (a complex genotype derived from V. vinifera and V. rupestris × V. aestivalis var. lincecumii), this cultivar was used for a cross with the susceptible variety 'Teroldego' (V. vinifera) and the segregating offspring was genetically characterized by means of the GrapeReSeq 18K Vitis SNP chip. Five phenotypic experiments were carried out under controlled conditions on leaves of potted plants, and three on bunches in the field. A dense genetic map was constructed combining 7,175 SNP with 194 SSR markers of a previous map. All QTL analyses revealed the presence of a strong major BR resistance locus on chromosome 14. It explains up to 45% of the trait variability (LOD 10.5) and spans a genomic region of 1.36 Mb. A specific SNP marker was found robustly associated with the resistance trait. No minor QTLs were detected. The genes underlying this region are currently under investigation via bioinformatic analysis, and microscopic inspections of disease progression are in place to understand the biological causes of the resistance trait. Finally, new molecular markers will be developed and validated on segregating populations with different genetic backgrounds, to be implemented in marker-assisted selection for BR resistance in grapevine. [ABSTRACT FROM AUTHOR]

Grapevine breeding for biotic stress resistance is a valuable strategy to embrace the principles of the European Green Deal, which will be one of the strongest drivers of the Agrifood research sector in the next decades. Grapevines are challenged by a range of diseases and pests, causing economic losses, and requiring often costly approaches to mitigate damage. Public interest in reducing the use of chemicals is a related challenge, along with climate change. All these aspects converge upon the urgent need for sustainable viticulture. The Vitis gene pool provides vast resources for the development of genetic resistance in rootstock and scion cultivars, but the search is not yet exhausted. According to BrAPI, germplasm consists of wild/acquired accessions as well as breeding products (breeding selections and cultivars). The enhancement of the entire germplasm is a crucial step. This is expressed in fingerprinting and high-throughput genotyping as well as phenotyping for disease and pest resistance, even in retroactive mode on traditional breeding products and acquired accessions. In fact, classical breeding approaches have made great strides in the development of cultivars with adaptive traits. Recent access to 'omic technologies, coupled with advanced phenotyping tools, has further facilitated the identification of useful loci, along with rapid trait introgression from wild species. Moreover, marker technologies (mainly accessible microsatellitebased systems) are now used in Marker-Assisted Selection to stack multiple loci/genes for the same trait into a single superior genotype. It would be relevant to phenotypically test these "stacked" genotypes in controlled lab settings as well as in different challenging environments worldwide. This effort would represent a step forward in terms of understanding genotype (loci) - pathogen (races) interaction. Genomic technologies will finally impact germplasm characterization, enabling the identification of candidate resistance genes and thereby facilitating "Breeding by Design" approaches. [ABSTRACT FROM AUTHOR]

An investigation was undertaken to adjudge the in vitro salt tolerance and biochemical changes due to NaCl on four grape rootstocks (Dogridge, SO4, H-144 and 3309C). The in vitro two-node micro-cuttings from the established cultures were sub-cultured on rooting medium comprising Murashige and Skoog (MS) basal medium supplemented with 0.5 μM indolebutyric acid (IBA), 200 mg dm−3 activated charcoal and different NaCl concentrations ranging from 0 to 125 mM. The surviving and proliferated cultures were further sub-cultured four times on respective media. Dogridge and H-144 tolerated 125 and 100 mM NaCl, respectively, while SO4 and 3309C survived only up to 75 mM NaCl. Contents of proteins, proline, K+ and Na+ in tissue increased in all genotypes due to NaCl supplementation, while contents of chlorophyll and total soluble sugars declined. Higher K+/Na+ ratio was registered in Dogridge and H-144 than in SO4 and 3309C. The relative NaCl tolerance for different grape rootstocks under study could be ranked as Dogridge > H-144 > SO4 and 3309C. [ABSTRACT FROM AUTHOR]

The efficiencies of two published primer pairs (RSP13-RSP14 and RSP2-RSP21) were compared in reverse transcription-polymerase chain reaction (RT-PCR) to improve the diagnosis of Grapevine rupestris stem pitting-associated virus (GRSPaV), which has consistently been found associated with rupestris stem pitting (RSP), one of the most common infectious diseases of grapevine. Fifty-six grapevine accessions from different locations in Northern Italy were tested. Of these, 48 were positive with primers RSP13-RSP14 and 37 with primers RSP2-RSP21, suggesting that primer pair RSP13-RSP14 has a broader detection spectrum than primers RSP2-RSP21. The coat protein (CP) gene was also amplified by RT-PCR and the amplicons analysed by single-strand conformation polymorphism (SSCP) and sequencing. The results support the existence of wide variability within this virus, independent of cultivar or geographic origin. Sequence analysis of the 17 Italian GRSPaV isolates examined showed a molecular identity ranging from 78·8 to 99·7%, within which, four groups of sequence variants were recognized. Flexuous rod-shaped particles, approximately 800 nm in length, were detected in plant extracts from infected grapevines and were positively decorated with the specific antiserum As7-276 in immunosorbent electron microscopy (ISEM). This is the first report of GRSPaV particles in grapevines observed by transmission electron microscopy (TEM) in Italy. [ABSTRACT FROM AUTHOR]

Adaptability, yield, quality attributes, and cumulative growing degree day (GDD) requirements of 'Barbera 02', 'Cabernet Sauvignon 02', 'Cabernet Sauvignon 04', 'Chardonnay 29', 'Merlot 01', and 'Sangiovese 04' wine grapes cultivar clones (Vitis sp.) under climatic conditions of southwest Idaho (Intermountain West region, USA) were evaluated during 2000 and 2001 seasons. 'Sangiovese 04' had significantly higher yield than 'Cabernet Sauvignon 02', 'Cabernet Sauvignon 04', 'Chardonnay 29', and 'Merlot 01' in both 2000 and 2001. 'Barbera 02' also had relatively higher yield than many other cultivar clones. 'Cabernet Sauvignon 02' had the lowest yield, although differences were not always significant. Other than cluster weight in 2000, no significant differences existed for yield, fruit quality attributes, or GDD requirements between the two 'Cabernet Sauvignon' clones ('Cabernet Sauvignon 02' and 'Cabernet Sauvignon 04'). 'Barbera 02' and 'Sangiovese 04' had the largest, while 'Cabernet Sauvignon 02' had the smallest clusters and berries among all tested cultivar clones. 'Cabernet Sauvignon 02' and 'Cabernet Sauvignon 04' had significantly greater soluble solids concentrations than 'Chardonnay 29' in both 2000 and 2001. 'Chardonnay 29', with an average of 2799 GDD, matured earlier than other grapes. Sangiovese 04' with an average of 3381 GDD days was the last grape to mature and be harvested. All tested cultivar clones can successfully be grown under conditions of this experiment. [ABSTRACT FROM PUBLISHER]