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White rot, caused by the fungus Coniella diplodiella, is an important but poorly studied disease that mainly affects grapevine clusters. White rot control typically involves the repeated application of fungicides, which may be unjustified in some cases given that the key period of berry susceptibility to infection remains unclear and controversial. In this study, germination of C. diplodiella conidia and mycelium growth were investigated on water agar (conidial germination only) and artificial media similar to berry juice at five growth stages from pea‐sized to berries ripe for harvest. On water agar, conidia germinated from 10°C to 35°C (with an optimum of 20–30°C) with >2 h of moisture incubation. Both conidial germination and mycelial growth were higher on agar similar to berry juice at véraison to berry softening than at other stages, with the lowest values detected for the ripe berries. The berries were also artificially inoculated with conidia at the different growth stages, showing that grape clusters were susceptible to infection for a long period, albeit with varying degrees of susceptibility at different stages. This implies that effective disease control requires interventions from early berry development, whenever weather conditions are conducive to infection. Further development of a predictive model accounting for weather conditions and berry susceptibility dynamics would facilitate the dynamic estimation of the disease risk during the grapevine‐growing season and contribute to a risk‐based application of fungicides for white rot control. [ABSTRACT FROM AUTHOR]

Some strains of nonpathogenic Allorhizobium vitis can control crown gall disease in grapevines caused by pathogenic A. vitis and are considered candidates for biocontrol agents. Many plant pathogenic bacteria regulate the expression of their virulence genes via quorum sensing using N -acylhomoserine lactone (AHL) as a signaling compound. The eight nonpathogenic A. vitis strains used in this study showed AHL-degrading activity. The complete genome sequence of A. vitis MAFF 212306 contained three AHL lactonase gene homologs. When these genes were cloned and transformed into Escherichia coli DH5α, E. coli harboring the aiiV gene (RvVAR031_27660) showed AHL-degrading activity. The aiiV coding region was successfully amplified by polymerase chain reaction from the genomes of all eight strains of nonpathogenic A. vitis. Purified His-tagged AiiV exhibited AHL lactonase activity by hydrolyzing the lactone ring of AHL. AiiV had an optimal temperature of approximately 30 °C; however, its thermostability decreased above 40 °C. When the AiiV-expressing plasmid was transformed into Pectobacterium carotovorum subsp. carotovorum NBRC 3830, AHL production by NBRC 3830 decreased below the detection limit, and its maceration activity, which was controlled by quorum sensing, almost disappeared. These results suggest the potential use of AHL-degrading nonpathogenic A. vitis for the inhibition of crown gall disease in grapevines and other plant diseases controlled by quorum sensing. [ABSTRACT FROM AUTHOR]

Grape white rot is a devastating fungal disease caused by Coniella diplodiella. The pathogen delivers effectors into the host cell that target crucial immune components to facilitate its infection. Here, we examined a secreted effector of C. diplodiella , known as CdE1, which has been found to inhibit Bax-triggered cell death in Nicotiana benthamiana plants. The expression of CdE1 was induced at 12–48 h after inoculation with C. diplodiella , and the transient overexpression of CdE1 led to increased susceptibility of grapevine to the fungus. Subsequent experiments revealed an interaction between CdE1 and Vitis davidii cysteine-rich receptor-like kinase 10 (VdCRK10) and suppression of VdCRK10-mediated immunity against C. diplodiella , partially by decreasing the accumulation of VdCRK10 protein. Furthermore, our investigation revealed that CRK10 expression was significantly higher and was up-regulated in the resistant wild grapevine V. davidii during C. diplodiella infection. The activity of the VdCRK10 promoter is induced by C. diplodiella and is higher than that of Vitis vitifera VvCRK10 , indicating the involvement of transcriptional regulation in CRK10 gene expression. Taken together, our results highlight the potential of VdCRK10 as a resistant gene for enhancing white rot resistance in grapevine. [ABSTRACT FROM AUTHOR]

Simple Summary: The inter-row management strategy in the vineyard influences the diversity of the vegetation and, consequently, the presence and activity of natural enemies of grapevine pests. This study aims to evaluate whether the replacement of periodical tillage with the alternate mowing of the resident herbaceous vegetation in vineyard inter-rows reduces the density of the European leafhoppers Hebata vitis and Zygina rhamni by improving the presence and activity of their natural enemies in the context of conservation biological control. The results show that, on grapevines with ground vegetation, the number of hunting spiders increases, thus reducing the leafhopper population with their predation activity. Green covering also improves hymenopteran parasitoids characterized for their important role in the grapevine pest control. A greater vegetation diversity in the vineyard improves the landscape quality of the agroecosystem and, by supporting the activity of the natural enemies of grapevine pests, reduces the need for insecticide applications in the vineyards. Inter-row management in vineyards can influence the abundance of grapevine pests and their natural enemies. In 2013–2015, in a vineyard in northeastern Italy, the influence of two vineyard inter-row management strategies (i.e., alternate mowing, AM, and periodical tillage, PT) on the population dynamics of grapevine leafhoppers Hebata vitis and Zygina rhamni and their natural enemies, the mymarid Anagrus atomus and spiders (Araneae), and other hymenopteran parasitoids, were studied with different survey approaches. The infestations of both leafhoppers were lower in AM than PT due to the reduced leafhopper oviposition and higher nymph mortality in AM. This occurred although leafhopper egg parasitization by A. atomus was greater in PT than AM according to a density-dependent relationship with the leafhopper egg amount. Hymenopteran parasitoids other than A. atomus were the most abundant in AM, probably due to the higher availability of nectar and pollen than in PM. The significantly higher population densities of hunting spiders in AM than PT can be associated with the higher predation of leafhopper nymphs. Therefore, the study demonstrated that the alternate mowing of vineyard inter-rows enhances the abundance of natural enemies, such as spiders and hymenopteran parasitoids, and can contribute to grapevine leafhopper pest control. [ABSTRACT FROM AUTHOR]

Pierce's disease (PD) is a vector-borne disease caused by the bacteria Xylella fastidiosa, which affects grapevines in the Americas. Currently, vineyards in continental Europe, the world's largest producer of quality wine, have not yet been affected by PD. However, climate change may alter this situation. Here we incorporate the latest regional climate change projections into a climate-driven epidemiological model to assess the risk of PD epidemics in Europe for different levels of global warming. We found a significant increase in risk above + 2 ∘ C in the main wine-producing regions of France, Italy and Portugal, in addition to a critical tipping point above + 3 ∘ C for the possible spread of PD beyond the Mediterranean. The model identifies decreasing risk trends in Spain, as well as contrasting patterns across the continent with different velocities of risk change and epidemic growth rates. Although there is some uncertainty in model projections over time, spatial patterns of risk are consistent across different climate models. Our study provides a comprehensive analysis of the future of PD at multiple spatial scales (country, Protected Designation of Origin and vineyard), revealing where, why and when PD could become a new threat to the European wine industry. [ABSTRACT FROM AUTHOR]

In viticulture, an intensive pesticide schedule is often required to control fungal and oomycete diseases and meet production standards. Accordingly, a reduction of synthetic fungicides and the application of environmentally-friendly crop protection alternatives are becoming increasingly important for a more sustainable viticulture. Even though the adoption of resistant/tolerant varieties is still limited in some traditional grape growing regions, the application of biological and/or physical tools, can in part substitute synthetic fungicides applications, and the use of decision support systems can help in reducing chemical treatments. This chapter presents the state of the art in grapevine protection to reduce pesticide use in viticulture and explores various alternative sustainable management strategies aimed to effectively control grapevine diseases triggered by fungi and oomycetes in nurseries, young and mature vineyards. [ABSTRACT FROM AUTHOR]

Traditional cultivated grapevine (Vitis vinifera) is susceptible to many fungal and oomycete pathogens causing devastating diseases including powdery mildew, downy mildew, grey mould, black rot and trunk diseases. These infections trigger various defence mechanisms such as reinforcement of the cell wall structure, production of phytoalexins and pathogenesis-related proteins, and localized cell death. In V. vinifera susceptible varieties, these defences are not effective, while in resistant grapevine, recognition of the pathogen induces effective mechanisms that stop the infection. Breeding programmes are conducted to take advantage of this genetic resistance. Moreover, a range of exogenous defence stimulators can be used to obtain a so-called "induced resistance" in susceptible varieties. This chapter presents the recently acquired knowledge on the molecular mechanisms involved in genetic and induced resistances, and further consider other mechanisms such as ontogenic resistance. It also suggests how to exploit these resistances to durably protect vineyards against the different fungal diseases. [ABSTRACT FROM AUTHOR]

Vitis vinifera L. possesses high economic value, but its growth and yield are seriously affected by salt stress. Though melatonin (MT) has been widely reported to enhance tolerance towards abiotic stresses in plants, the regulatory role melatonin plays in resisting salt tolerance in grapevines has scarcely been studied. Here, we observed the phenotypes under the treatment of different melatonin concentrations, and then transcriptome and metabolome analyses were performed. A total of 457 metabolites were detected in CK- and MT-treated cell cultures at 1 WAT (week after treatment) and 4 WATs. Exogenous melatonin treatment significantly increased the endogenous melatonin content while down-regulating the flavonoid content. To be specific, the melatonin content was obviously up-regulated, while the contents of more than a dozen flavonoids were down-regulated. Auxin response genes and melatonin synthesis-related genes were regulated by the exogenous melatonin treatment. WGCNA (weighted gene coexpression network analysis) identified key salt-responsive genes; they were directly or indirectly involved in melatonin synthesis and auxin response. The synergistic effect of salt and melatonin treatment was investigated by transcriptome analysis, providing additional evidence for the stress-alleviating properties of melatonin through auxin-related pathways. The present study explored the impact of exogenous melatonin on grapevines' ability to adapt to salt stress and provided novel insights into enhancing their tolerance to salt stress. [ABSTRACT FROM AUTHOR]

Background and aims Xylella fastidiosa (Xf) is the xylem-dwelling bacterium associated with Pierce's disease (PD), which causes mortality in agriculturally important species, such as grapevine (Vitis vinifera). The development of PD symptoms in grapevines depends on the ability of Xf to produce cell-wall-degrading enzymes to break up intervessel pit membranes and systematically spread through the xylem vessel network. Our objective here was to investigate whether PD resistance could be mechanistically linked to xylem vessel network local connectivity. Methods We used high-resolution X-ray micro-computed tomography (microCT) imaging to identify and describe the type, area and spatial distribution of intervessel connections for six different grapevine genotypes from three genetic backgrounds, with varying resistance to PD (four PD resistant and two PD susceptible). Key results Our results suggest that PD resistance is unlikely to derive from local xylem network connectivity. The intervessel pit area (A i) varied from 0.07 ± 0.01 mm2 mm−3 in Lenoir to 0.17 ± 0.03 mm2 mm−3 in Blanc do Bois, both PD resistant. Intervessel contact fraction (C p) was not statically significant, but the two PD-susceptible genotypes, Syrah (0.056 ± 0.015) and Chardonnay (0.041 ± 0.013), were among the most highly connected vessel networks. Neither A i nor C p explained differences in PD resistance among the six genotypes. Bayesian re-analysis of our data shows moderate evidence against the effects of the traits analysed: A i (BF01 = 4.88), mean vessel density (4.86), relay diameter (4.30), relay density (3.31) and solitary vessel proportion (3.19). Conclusions Our results show that radial and tangential xylem network connectivity is highly conserved within the six different Vitis genotypes we sampled. The way that Xf traverses the vessel network may limit the importance of local network properties to its spread and may confer greater importance on host biochemical responses. [ABSTRACT FROM AUTHOR]

The successful implementation of deep learning nets opens up possibilities for various applications in viticulture, including disease detection, plant health monitoring, and grapevine variety identification. With the progressive advancements in the domain of deep learning, further advancements and refinements in the models and datasets can be expected, potentially leading to even more accurate and efficient classification systems for grapevine leaves and beyond. Overall, this research provides valuable insights into the potential of deep learning for agricultural applications and paves the way for future studies in this domain. This work employs a convolutional neural network (CNN)-based architecture to perform grapevine leaf image classification by adapting VGG-16 net and VGG-19 net models and subsequently identifying the optimal performer between the two nets during the classification process. A publicly available dataset comprising 500 images categorized into 5 distinct classes (100 images per class), was utilized in this work. The obtained empirical outcomes demonstrate a remarkable accuracy rate of 99.6% for the VGG-16 net model, while VGG-19 net achieves a 100% accuracy rate. Based on these findings, it can be inferred that VGG-19 net exhibits superior performance in classifying images of grapevine leaves compared to the VGG-16 net. [ABSTRACT FROM AUTHOR]

Downy mildew of grapevine (Vitis vinifera), caused by the oomycete Plasmopara viticola, is an important disease that is present in cultivation areas worldwide, and using resistant varieties provides an environmentally friendly alternative to fungicides. DOWNY MILDEW RESISTANT 6 (DMR6) from Arabidopsis is a negative regulator of plant immunity and its loss of function confers resistance to downy mildew. In grapevine, DMR6 is present in two copies, named VvDMR6-1 and VvDMR6-2. Here, we describe the editing of VvDMR6-1 in embryogenic calli using CRISPR/Cas9 and the regeneration of the edited plants. All edited plants were found to be biallelic and chimeric, and whilst they all showed reduced growth compared with non-transformed control plants, they also had reduced susceptibility to P. viticola. Comparison between mock-inoculated genotypes showed that all edited lines presented higher levels of salicylic acid than controls, and lines subjected to transformation presented higher levels of cis-resveratrol than controls. Our results identify VvDMR6-1 as a promising target for breeding grapevine cultivars with improved resistance to downy mildew. [ABSTRACT FROM AUTHOR]

Lambda cyhalothrin is frequently used to combat defoliating insects, especially beetles, however it also has a significant impact on naturally occurring non-target species. Two grape epiphytic bacteria, Bacillus inaquosorum strain LC1 and Bacillus spizizenii strain LC2, were found to degrade lambda cyhalothrin. The biodegradation of pesticide in a liquid medium, in soil and on grape berries was investigated. In liquid medium on day 0, approximately 4.5 μg/ml of lambda cyhalothrin was detected in all the test and control broth. The concentration of lambda cyhalothrin in control, LC1 treated broth and LC2 treated broth was 3.66 μg/ml, 1.83 μg/ml and 1.41 μg/ml respectively, after 10 days. Maximum degradation of lambda cyhalothrin was shown by LC2 bacteria in comparison to control. During the field study, the average degradation of lambda cyhalothrin for both the years was 66.13% by isolate LC 1 and 80.79% by LC2. The average natural degradation of lambda cyhalothrin was 37.50% in control. The degradation efficiency of LC1, when compared to autoclaved soil, was high in non-autoclaved soil. indicating that the natural microflora of soil affected the degradation process of LC1. On the other hand, the degradation efficiency of LC2 in non-autoclaved soil and on grape berries was high which suggested that the bacteria were able to live through, in addition to competing with other microorganisms under field environment. [ABSTRACT FROM AUTHOR]

Esca is a grapevine trunk disease (GTD) that is caused by filamentous fungi. It is responsible for considerable economic losses in viniculture on a global scale. Despite many unknown factors contributing to the development of symptoms in affected plants, Phaeoacremonium minimum (PMI), Phaeomoniella chlamydospora (PCH) and Fomitiporia mediterranea (FMED) are generally considered as the main causative fungal species. Early detection and specific identification of these pathogens therefore play an important role in disease control and evaluation of suitable countermeasures. In this study, loop‐mediated isothermal amplification (LAMP) assays were developed for each of the three pathogens. A genome‐based approach was applied for detection and selection of unique target DNA sequences. The designed primer sets showed overall good specificities, with some observed cross‐reactions towards closely related Phaeoacremonium species for the PMI primer set. The developed assays had detection limits of 100 pg (FMED, PMI) and 1 pg (PCH) per reaction (corresponding to 1460 [FMED]; 1950 [PMI]; 342 [PCH] genome copies per reaction). The application of the assays to field samples was demonstrated by testing individual infected grapevine trunks from two European viticultural regions using crude DNA obtained in a rapid sample preparation step. LAMP assay results matched those of PCR following a conventional DNA extraction protocol. The study showed that LAMP‐based rapid molecular detection of major Esca agents can serve as a useful tool for further research and surveillance of a highly devastating grapevine disease. The application of computer‐based whole genome comparison between target and non‐target species for the identification of unique target sequences as the basis for LAMP (or PCR) primer design was demonstrated to be a useful approach in species for which scarce sequence information is available. Moreover, the developed method for rapid DNA preparation from grapevine trunks may potentially be adapted to the DNA‐based detection also of other fungal species that cause grapevine trunk diseases. [ABSTRACT FROM AUTHOR]

Botryosphaeriaceae are fungi involved in the decay of various woody species, including the grapevine, leading to significant production losses. This fungal family is largely ubiquitous, and seven species of Botryosphaeriaceae have been identified in French vineyards, with variable levels of aggressiveness, both in vitro and in planta. Mycoviruses can impact the life traits of their fungal hosts, including aggressiveness, and are one of the factors influencing fungal pathogenicity. In this study, the RNA mycovirome of fifteen Botryosphaeriaceae isolates was characterized through the high-throughput sequencing of double-stranded RNA preparations from the respective samples. Eight mycoviruses were detected, including three potential novel species in the Narnaviridae family, as well as in the proposed Mycobunyaviridae and Fusagraviridae families. A large collection of Botryosphaeriaceae isolates was screened using RT-PCR assays specific for 20 Botryosphaeriaceae-infecting mycoviruses. Among the mycoviruses detected, some appeared to be specialists within a single host species, while others infected isolates belonging to multiple Botryosphaeriaceae species. This screening allowed us to conclude that one-third of the Botryosphaeriaceae isolates were infected by at least one mycovirus, and a significant proportion of isolates (43.5%) were found to be coinfected by several viruses, with very complex RNA mycoviromes for some N. parvum isolates. [ABSTRACT FROM AUTHOR]

Eutypa dieback of grapevine is a trunk disease that impacts vineyard productivity worldwide. Grape germplasm is typically evaluated for resistance to Eutypa dieback through controlled inoculations in the greenhouse, although the high level of replication required of this approach (40 plants per genotype) can limit the total number of genotypes evaluated. An alternative approach is to evaluate naturally infected genotypes in the field. We rated the incidence and severity of vines with the diagnostic leaf symptoms of Eutypa dieback and the incidence of mortality among such vines of 973 Vitis vinifera accessions (planted in duplicate) at the US Department of Agriculture, National Clonal Germplasm Repository in Davis, CA, USA, which is maintained as a living collection for grape research. Across 3 years and spanning a total of 5 years (2011, 2013, and 2015), 120 accessions had leaf symptoms in one or more years ("susceptible accessions"). Courbu blanc [Davis Vitis identification tag (DVIT) 2313], Frankenthal blanc (DVIT 2115), and Pinot gris (DVIT 0907) were the only accessions with leaf symptoms each year. Accessions with the most severe leaf symptoms (a rating of 5 points) were Chasselas Napoleon (DVIT 0375) and Queen of the Vineyard (DVIT 0496). We identified susceptible accessions--namely, those related to 'Chasselas' and 'Muscat'--with a shared genetic background, based on a previous single nucleotide polymorphism genotyping effort of the collection. Especially for grapevine, a long-lived perennial that is meant to produce a crop for decades, knowledge of susceptible accessions and their pedigrees can help inform breeding programs and studies on the host response to infection. [ABSTRACT FROM AUTHOR]

Recently, grapevine trunk diseases have been considered the most destructive of grapevine species in Morocco. Several damages are observed annually in vineyards by these destructive diseases in vineyards. Botryosphaeria dieback is one of the major responsible of these wasting diseases. Symptoms include sectorial and central necrosis, brown bands or cracks, discolorations and withering on the foliar surface. Botryosphaeria dieback symptomatology, associated fungi, host-pathogen interaction, and control methods are the topics of this review. [ABSTRACT FROM AUTHOR]

Background: Crown gall disease caused by Agrobacterium tumefaciens is a very destructive affliction that affects grapevines. Endophytic bacteria have been discovered to control plant diseases via the use of several mechanisms. This research examined the potential for controlling crown gall by three endophytic bacteria that were previously isolated from healthy cultivated and wild grapevines including Pseudomonas kilonensis Ba35, Pseudomonas chlororaphis Ba47, and Serratia liquefaciens Ou55. Result: At various degrees, three endophytic bacteria suppressed the populations of A. tumefaciens Gh1 and greatly decreased the symptoms of crown gall. Furthermore, biofilm production and motility behaviors of A. tumefaciens Gh1were greatly inhibited by the Cell-free Culture Supernatant (CFCS) of endophytic bacteria. According to our findings, CFCS may reduce the adhesion of A. tumefaciens Gh1 cells to grapevine cv. Rashe root tissues as well as their chemotaxis motility toward the extract of the roots. When compared to the untreated control, statistical analysis showed that CFCS significantly reduced the swimming, twitching, and swarming motility of A. tumefaciens Gh1. The findings demonstrated that the endophytic bacteria effectively stimulated the production of plant defensive enzymes including superoxide dismutase (SOD), polyphenol oxidase (PPO), peroxidase (POD), phenylalanine ammonia lyase (PAL), and total soluble phenols at different time intervals in grapevine inoculated with A. tumefaciens Gh1. The Ba47 strain markedly increased the expression levels of defense genes associated with plant resistance. The up-regulation of PR1, PR2, VvACO1, and GAD1 genes in grapevine leaves indicates the activation of SA and JA pathways, which play a role in enhancing resistance to pathogen invasion. The results showed that treating grapevine with Ba47 increased antioxidant defense activities and defense-related gene expression, which reduced oxidative damage caused by A. tumefaciens and decreased the incidence of crown gall disease. Conclusion: This is the first study on how A. tumefaciens, the grapevine crown gall agent, is affected by CFCS generated by endophytic bacteria in terms of growth and virulence features. To create safer plant disease management techniques, knowledge of the biocontrol processes mediated by CFCS during microbial interactions is crucial. [ABSTRACT FROM AUTHOR]

A comprehensive study was conducted on the prevalence of grapevine trunk diseases in Greece, focusing specifically on contamination of grapevine propagation material by Phaeomoniella chlamydospora and black foot disease‐related species. Additionally, detection of esca pathogen Fomitiporia mediterranea, causing white rot in grapevine and other woody hosts, was assessed using a new PCR‐based assay that distinguishes F. mediterranea from F. punctata. Development of a nested PCR assay, combined with a cost‐effective DNA extraction protocol, revealed a high percentage of infection by P. chlamydospora (51%) and Ilyonectria species associated with black foot disease (28%) in different types of grapevine propagation material (dormant cuttings, field‐rooted benchgrafts and green‐growing plants). Interestingly, black foot disease‐related pathogens were more prevalent in nursery plants grown in the field for 6 months (57%) than in other types of propagation material and compared with P. chlamydospora (43%), indicating increased infection of propagation material during growth in the nursery field. The cost‐effective molecular method developed in this study could be used in mass inspections of propagation material for phytosanitary purposes. Finally, using primers specific for F. mediterranea and F. puncata developed in this study, combined with the universal ITS4 primer, a collection of Fomitiporia isolates from mature grapevine and other woody hosts from Greece and Italy (southern Europe) were characterized as F. mediterranea, whereas German and Swedish isolates from forest plants (central Europe) were classified as F. punctata. The developed primers can discriminate between the two Fomitiporia species, which are indistinguishable based on culture and morphological characteristics alone. [ABSTRACT FROM AUTHOR]

Plant diseases and pests reduce crop yields, accounting for global crop losses of 30% to 50%. In conventional agricultural production systems, these losses are typically controlled by applying chemical pesticides. However, public pressure is mounting to curtail agrochemical use. In this context, employing beneficial endophytic microorganisms is an increasingly attractive alternative to the use of conventional chemical pesticides in agriculture. A multitude of fungal endophytes are naturally present in plants, producing enzymes, small peptides, and secondary metabolites due to their bioactivity, which can protect hosts from pathogens, pests, and abiotic stresses. The use of beneficial endophytic microorganisms in agriculture is an increasingly attractive alternative to conventional pesticides. The aim of this study was to characterize fungal endophytes isolated from apparently healthy, feral wine grapes in eastern Canada that have grown without agrochemical inputs for decades. Host plants ranged from unknown seedlings to long-lost cultivars not widely propagated since the 1800s. HPLC-MS was used to identify unique endophyte-derived chemical compounds in the host plants, while dual-culture competition assays showed a range in endophytes' ability to suppress the mycelial growth of Botrytis, which is typically controlled in viticulture with pesticides. Twelve of the most promising fungal endophytes isolated were identified using multilocus sequencing and morphology, while DNA barcoding was employed to identify some of their host vines. These fungal endophyte isolates, which consisted of both known and putative novel strains, belonged to seven genera in six families and five orders of Ascomycota. Exploring the fungal endophytes in these specimens may yield clues to the vines' survival and lead to the discovery of novel biocontrol agents. [ABSTRACT FROM AUTHOR]

BACKGROUND: Grapevine red blotch virus (GRBV) is a recently discovered virus and a major concern for the wine industry. Prior research indicated that GRBV delays grape ripening by reducing °Brix and anthocyanin concentrations in grapes from infected vines, resulting in higher ethanol concentrations in wines made from healthy fruit compared to diseased vines, which have an impact on sensory properties. In this study, infected fruit (Vitis vinifera L. Merlot) was sequentially harvested (in 2016 and 2017) and chaptalized (in 2017) to ameliorate the impact of GRBV on grape and final wine composition. RESULTS: Chemical parameters including phenolic and volatile profiles of grapes and their subsequent wines were measured. Sensory properties were determined by descriptive analyses. Results demonstrated that GRBV decreased sugar accumulation and anthocyanin synthesis in grapes. Wines from GRBV grapes harvested at later ripening stage produced wines that were more similar chemically and sensorially to wines made from healthy fruit than to wines made from GRBV fruit harvested earlier. CONCLUSION: A longer hang time of GRBV grapes is a potential strategy to mitigate the impacts of GRBV. However, chaptalization of diseased fruit must was inefficient at increasing similarities to wines made from healthy fruit. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Botrytis cinerea is the causative agent of grey mould disease in grapes, which was linked to significant postharvest losses. This study examined three grape‐isolated yeasts (Metschnikowia aff. fructicola, Metschnikowia pulcherrima, and Hansenispora uvarum) through in vitro and in vivo tests on detached grape berries against grey mould, as well as the elucidation of their possible mechanisms of action. The antifungal mechanism of action of yeasts was determined by the lytic enzyme activity, inhibition of spore germination, biofilm activity, iron depletion, diffusible metabolites, wound‐site colonisation, mycocin, and volatile organic compounds (VOCs) production. The highest in vitro efficacy (83.13%) was observed on M. aff. fructicola, followed by M. pulcherrima (82.10%) and H. uvarum (71.66%). Metschnikowia yeasts exhibited comparable enzyme activities, including protease, β‐1,3 glucanase, gelatinase chitinase, and cellulase, while H. uvarum had a poor enzymatic activity with chitinase and gelatinase. M. aff. fructicola showed relatively higher iron depletion activity than M. pulcherrima, while M. pulcherrima outperformed via diffusible metabolites. All yeast cultures significantly reduced spore germination by at least 86%. Overall, M. aff. fructicola exhibited the highest biocontrol activity with its iron depletion, inhibition of conidial germination, biofilm formation, VOCs, and well colonisation on grape berries. M. aff. fructicola 1‐UDM outperformed all other yeasts by significantly reducing disease incidence and lesion diameter values (93.4% and 94.3%, respectively). Remarkably, H. uvarum VOCs demonstrated potential as a biofumigant for suppressing grey mould. All yeasts are well adapted to their ecological niche to bio‐protect grapes from grey mould disease. [ABSTRACT FROM AUTHOR]

Xylella fastidiosa is a vector-borne xylem-limited bacterium of agricultural and economic importance, yet it remains to be demonstrated how this pathogen is inoculated into plants by insect vectors. Recent DC-EPG (Electrical Penetration Graph) research with the meadow spittlebug, Philaenus spumarius tentatively correlated bacterial inoculation with a non-stereotypical "spiking waveform" termed Xe; this behavior occurred within the first minutes from initial stylets contact with a xylem vessel. Here, using the Graphocephala atropunctata-grapevine-X. fastidiosa pathosystem, we conclusively demonstrate that the DC-EPG waveform Xe represents the vector probing behavior correlated with X. fastidiosa inoculation into a host plant, and successful systemic persistent pathogen infection. Our work supports the previous hypothesis that Xe represents an egestion behavior, with a mixture of xylem sap-bacterial cells propelled by the collapse of the cibarial diaphragm while the precibarial valve is fluttering, potentially to remove obstructions from the precibarium and its chemosensilla. The outward flow delivering the mixture sap-bacterial cells into the plant is permitted by the valve that flutters instead of sealing the food canal. The inoculation behavior Xe is more frequent in vectors harboring X. fastidiosa cells within the foregut, independent of the bacterial population size in insects. [ABSTRACT FROM AUTHOR]

Shiraz disease (SD) is one of the most destructive viral diseases of grapevines in Australia and is known to cause significant economic loss to local growers. Grapevine virus A (GVA) was reported to be the key pathogen associated with this disease. This study aimed to better understand the diversity of GVA variants both within and between individual SD and grapevine leafroll disease (LRD) affected grapevines located at vineyards in South Australia. Amplicon high throughput sequencing (Amplicon-HTS) combined with median-joining networks (MJNs) was used to analyze the variability in specific gene regions of GVA variants. Several GVAII variant groups contain samples from both vineyards studied, suggesting that these GVAII variants were from a common origin. Variant groups analyzed by MJNs using the overall data set denote that there may be a possible relationship between variant groups of GVA and the geographical location of the grapevines. [ABSTRACT FROM AUTHOR]

A three-year survey was conducted to estimate the incidence of grapevine trunk diseases (GTDs) in Greece and identify fungi associated with the disease complex. In total, 310 vineyards in different geographical regions in northern, central, and southern Greece were surveyed, and 533 fungal strains were isolated from diseased vines. Morphological, physiological and molecular (5.8S rRNA gene-ITS sequencing) analyses revealed that isolates belonged to 35 distinct fungal genera, including well-known (e.g., Botryosphaeria sp., Diaporthe spp., Eutypa sp., Diplodia sp., Fomitiporia sp., Phaeoacremonium spp., Phaeomoniella sp.) and lesser-known (e.g., Neosetophoma sp., Seimatosporium sp., Didymosphaeria sp., Kalmusia sp.) grapevine wood inhabitants. The GTDs-inducing population structure differed significantly among the discrete geographical zones. Phaeomoniella chlamydospora (26.62%, n = 70), Diaporthe spp. (18.25%, n = 48) and F. mediterranea (10.27%, n = 27) were the most prevalent in Heraklion, whereas D. seriata, Alternaria spp., P. chlamydospora and Fusarium spp. were predominant in Nemea (central Greece). In Amyntaio and Kavala (northern Greece), D. seriata was the most frequently isolated species (>50% frequency). Multi-genes (rDNA-ITS, LSU, tef1-α, tub2, act) sequencing of selected isolates, followed by pathogenicity tests, revealed that Neosetophoma italica, Seimatosporium vitis, Didymosphaeria variabile and Kalmusia variispora caused wood infection, with the former being the most virulent. To the best of our knowledge, this is the first report of N. italica associated with GTDs worldwide. This is also the first record of K. variispora, S. vitis and D. variabile associated with wood infection of grapevine in Greece. The potential associations of disease indices with vine age, cultivar, GTD-associated population structure and the prevailing meteorological conditions in different viticultural zones in Greece are presented and discussed. [ABSTRACT FROM AUTHOR]

Species from the Botryosphaeriaceae family are the causal agents of Botryosphaeria dieback (BD), a worldwide grapevine trunk disease. Because of their lifestyle and their adaptation to a wide range of temperatures, these fungi constitute a serious threat to vineyards and viticulture, especially in the actual context of climate change. Grapevine plants from both nurseries and vineyards are very susceptible to infections by botryosphaeriaceous fungi due to several cuts and wounds made during their propagation process and their entire life cycle, respectively. When decline becomes chronic or apoplectic, it reduces the longevity of the vineyard and affects the quality of the wine, leading to huge economic losses. Given the environmental impact of fungicides, and their short period of effectiveness in protecting pruning wounds, alternative strategies are being developed to fight BD fungal pathogens and limit their propagation. Among them, biological control has been recognized as a promising and sustainable alternative. However, there is still no effective strategy for combating this complex disease, conditioned by both fungal life traits and host tolerance traits, in relationships with the whole microbiome/microbiota. To provide sound guidance for an effective and sustainable integrated management of BD, by combining the limitation of infection risk, tolerant grapevine cultivars, and biological control, this review explores some of the factors conditioning the expression of BD in grapevine. Among them, the lifestyle of BD-associated pathogens, their pathogenicity factors, the cultivar traits of tolerance or susceptibility, and the biocontrol potential of Bacillus spp. and Trichoderma spp. are discussed. [ABSTRACT FROM AUTHOR]

In the presented study, isolation of bacterial strains, viz., Pantoea agglomerans, Priestia megaterium and phytopathogenic micromycetes that cause damage and eventually death of grape crops, came from a 10 to 15-year-old vine plantation. A Pantoea agglomerans gram-negative bacillus facultative and anaerobic bacterium strain achieved isolation from grape plants, with its morphological characteristics studied. Bacterial strains with antifungal activities against phytopathogenic micromycetes succeeded in their identification. Bacterial isolates collected from the vines underwent screening for their growth properties. It was apparent that Pantoea agglomerans actively grew wheat coleoptiles by 2.6 mm and maize coleoptiles by 2.3 mm compared with the control. Observable evidence also showed that sorghum coleoptile actively grew by 1.7 mm compared with the control treatment by 2.9 mm. The 26 Aspergillus sp., 23 Penicillium sp., 25 Fusarium sp., 30 Alternaria sp., and five Curvularia sp. phytopathogenic micromycetes belonging to the genus were notable. Bacterial strains isolated from the vine showed the highest antifungal activity against micromycetes belonging to the genus Penicillium and reduced the radius of phytopathogenic growth to 47-54 mm. Compared with micromycetes belonging to the genus Fusarium, it was also apparent that the pathogen reduced the growth radius to 27-35 mm. Isolation of phytopathogenic micromycetes from the vine allows early detection and prevention of grape diseases. Based on these studies, the identification of antifungal activity of the bacterial strains isolated from the vine and the presence of phytohormones in the culture fluid indicated that it is an essential and environmentally friendly biological tool in the cultivation of grapes for human consumption. [ABSTRACT FROM AUTHOR]

Young grapevines (Vitis vinifera) suffer and eventually can die from the crown gall disease caused by the plant pathogen Allorhizobium vitis (Rhizobiaceae). Virulent members of A. vitis harbor a tumor-inducing plasmid and induce formation of crown galls due to the oncogenes encoded on the transfer DNA. The expression of oncogenes in transformed host cells induces unregulated cell proliferation and metabolic and physiological changes. The crown gall produces opines uncommon to plants, which provide an important nutrient source for A. vitis harboring opine catabolism enzymes. Crown galls host a distinct bacterial community, and the mechanisms establishing a crown gall–specific bacterial community are currently unknown. Thus, we were interested in whether genes homologous to those of the tumor-inducing plasmid coexist in the genomes of the microbial species coexisting in crown galls. We isolated 8 bacterial strains from grapevine crown galls, sequenced their genomes, and tested their virulence and opine utilization ability in bioassays. In addition, the 8 genome sequences were compared with 34 published bacterial genomes, including closely related plant-associated bacteria not from crown galls. Homologous genes for virulence and opine anabolism were only present in the virulent Rhizobiaceae. In contrast, homologs of the opine catabolism genes were present in all strains including the nonvirulent members of the Rhizobiaceae and non-Rhizobiaceae. Gene neighborhood and sequence identity of the opine degradation cluster of virulent and nonvirulent strains together with the results of the opine utilization assay support the important role of opine utilization for cocolonization in crown galls, thereby shaping the crown gall community. [ABSTRACT FROM AUTHOR]

High temperatures associated with a fluctuating climate profoundly accelerate the occurrence of a myriad of plant diseases around the world. A comprehensive insight into how plants respond to pathogenic microorganisms under high-temperature stress is required for plant disease management, whereas the underlying mechanisms behind temperature-mediated plant immunity and pathogen pathogenicity are still unclear. Here, we evaluated the effect of high temperature on the development of grapevine canker disease and quantified the contribution of temperature variation to the gene transcription reprogramming of grapevine and its pathogenic agent Lasiodiplodia theobromae using a dual RNA-seq approach. The results showed that both grapevine and the pathogen displayed altered transcriptomes under different temperatures, and even the transcription of a plethora of genes from the two organisms responded in different directions and magnitudes. The transcription variability that arose due to temperature oscillation allowed us to identify a total of 26 grapevine gene modules and 17 fungal gene modules that were correlated with more than one gene module of the partner organism, which revealed an extensive web of plant–pathogen gene reprogramming during infection. More importantly, we identified a set of temperature-responsive genes that were transcriptionally orchestrated within the given gene modules. These genes are predicted to be involved in multiple cellular processes including protein folding, stress response regulation, and carbohydrate and peptide metabolisms in grapevine and porphyrin- and pteridine-containing compound metabolisms in L. theobromae, implying that in response to temperature oscillation, a complex web of signaling pathways in two organism cells is activated during infection. This study describes a co-transcription network of grapevine and L. theobromae in the context of considering temperature variation, which provides novel insights into deciphering the molecular mechanisms underlying temperature-modulated disease development. [ABSTRACT FROM AUTHOR]

In this study, we focused on grapevine–endophyte interactions and reprogrammed secondary metabolism in the host plant due to defense against the colonization of endophytes. Thus, the transcriptional responses of tissue cultured grapevine seedlings (Vitis vinifera L. cv.: Cabernet Sauvignon) to two fungal endophytes Epicoccum layuense R2-21 (Epi R2-21) and Alternaria alternata XHYN2 (Alt XHYN2) at three different time points (6 h, 6 d, 15 d) were analyzed. As expected, a total of 5748 and 5817 differentially expressed genes (DEGs) were separately initiated in Epi R2-21 and Alt XHYN2 symbiotic tissue cultured seedlings compared to no endophyte treatment. The up-regulated DEGs at all time points in Epi R2-21- or Alt XHYN2–treated seedlings were mainly enriched in the flavonoid biosynthesis, phenylpropanoid biosynthesis, phenylalanine metabolism, stilbenoid, diarylheptanoid and gingerol biosynthesis, and circadian rhythm–plant pathways. In addition, the up-regulated DEGs at all sampling times in Alt XHYN2-treated tissue cultured seedlings were enriched in the plant–pathogen interaction pathway, but appeared in Epi R2-21 symbiotic seedlings only after 15 d of treatment. The down-regulated DEGs were not enriched in any KEGG pathways after 6 h inoculation for Epi R2-21 and Alt XHYN2 treatments, but were enriched mainly in photosynthesis–antenna proteins and plant hormone signal transduction pathways at other sampling times. At three different time points, a total of 51 DEGs (all up-regulated, 1.33–10.41-fold) were involved in secondary metabolism, and 22 DEGs (all up-regulated, 1.01–8.40-fold) were involved in defense responses in endophytic fungi symbiotic tissue cultured seedlings. The protein–protein interaction (PPI) network demonstrated that genes encoding CHS (VIT_10s0042g00920, VIT_14s0068g00920, and VIT_16s0100g00910) and the VIT_11s0065g00350 gene encoding CYP73A mediated the defense responses, and might induce more defense-associated metabolites. These results illustrated the activation of stress–associated secondary metabolism in the host grapevine during the establishment of fungi–plant endophytism. This work provides avenues for reshaping the qualities and characteristics of wine grapes utilizing specific endophytes and better understanding plant–microbe interactions. [ABSTRACT FROM AUTHOR]

White rot, caused by Coniella vitis, is a devastating disease in grapevine (Vitis vinifera) that seriously affects yield and quality. Breeding resistant grapevine varieties is a highly economical, environmentally friendly, and effective strategy to protect against the disease; however, this strategy requires a comprehensive understanding of the genes and pathways related to resistance. In this study, we sequenced the transcriptome of V. vinifera L. cv. GF, a highly resistant variety, at six time points after C. vitis inoculation. A transcriptome analysis showed that the salicylic acid (SA) signaling pathway was activated in response to C. vitis. Transient silencing of the VvTGA8 gene in the cv. GF greatly increased susceptibility to C. vitis. Subcellular localization studies showed that the VvTGA8 gene is localized in the nucleus. Heterologous expression of VvTGA8 in Solanum lycopersicum improved resistance to C. vitis and increased levels of the SA signaling pathway marker genes SlPR1 and SlPR2 significantly. To explore the mechanism by which VvTGA8 mediates disease resistance, we silenced SlICS1, a key gene in the SA synthesis pathway, through virus-induced gene silencing to inhibit SA synthesis in a VvTGA8 overexpression line, resulting in significantly weakened resistance to C. vitis and decreased expression levels of SlPR1 and SlPR2. We conclude that VvTGA8 is involved in SA signaling pathway, which activates the expression of pathogenesis-related genes in the nucleus, thereby mediating resistance to C. vitis in grapevine. This study provides an excellent target gene for disease-resistant breeding and gene editing in grapevine. [ABSTRACT FROM AUTHOR]

Grapevine (Vitis vinifera L.) is one of the most widespread and economically important fruit crops in the world based on its capacity to produce high yields of quality fruit, hectares cultivated and its ability to grow in a wide range of climates and soils. However, it is greatly exposed to a wide variety of pathogens, affecting production and fruit quality. Among the potential threats, Allorhizobium vitis, the causal agent of grapevine crown gall represents a limiting factor in grape production worldwide. It causes vine decline and mortality especially in young vineyards and orchards with important economic losses. Owing of the systemic survival of Allorhizobium vitis in grapevine, copper bactericides and antibiotics are ineffective, and they are able to kill only the bacterium on contact. Therefore, the knowledge of pathogen, effective control and prevention strategies, and sensitive detection methods of pathogen are needed to improve the management of the disease. This review highlights the current state of research and the major acquisitions in this field and provides efficient procedures for isolating from tumors and soil. In addition, this paper discusses the different strategies used for the management of grapevine crown gall along with their drawbacks. Moreover, detection methods for rapid and proper identification of the disease bacteria were provided to enhance the efficiency of control measures and prevent the spread of the pathogen. [ABSTRACT FROM AUTHOR]

The genus Elsinoe includes many aggressive plant pathogens that infect various economically important agricultural, horticultural and forestry plants. Significant diseases include citrus scab caused by E. fawcettii and E. australis , grapevine spot anthracnose by E. ampelina , and the emerging Eucalyptus scab and shoot malformation disease caused by the recently described E. necatrix. Despite their importance as plant pathogens, little is known regarding the biology of many Elsinoe spp. To gain insights into the reproductive biology of these fungi, we characterized the mating-type loci of seven species using whole genome sequence data. Results showed that the MAT1 locus organization and its flanking genes is relatively conserved in most cases. All seven species manifested a typical heterothallic mating system characterized by having either the MAT1-1 or MAT1-2 idiomorph present in an isolate. These idiomorphs were defined by the MAT1-1-1 or the MAT1-2-1 gene, respectively. A unique MAT1-1 idiomorph containing a truncated MAT1-2-1 gene, and a MAT1-1-1 gene, was identified in E. necatrix and E. fawcettii genomes. Additionally, two idiomorph-specific proteins were found in the MAT1-1 and MAT1-2 idiomorphs of E. australis. Universal mating-type markers confirmed heterothallism across 21 Elsinoe spp. , are poised to advance future studies regarding the biology of these fungi. [ABSTRACT FROM AUTHOR]

Alternaria, a cosmopolitan fungal genus is a dominant member of the grapevine (Vitis vinifera) microbiome. Several Alternaria species are known to produce a variety of secondary metabolites, which are particularly relevant to plant protection and food safety in field crops. According to previous findings, the majority of Alternaria species inhabiting grapevine belong to Alternaria sect. Alternaria. However, the phylogenetic diversity and secondary metabolite production of the distinct Alternaria species has remained unclear. In this study, our aim was to examine the genetic and metabolic diversity of endophytic Alternaria isolates associated with the above-ground tissues of the grapevine. Altogether, 270 Alternaria isolates were collected from asymptomatic leaves and grape clusters of different grapevine varieties in the Eger wine region of Hungary. After analyses of the nuclear ribosomal DNA internal transcribed spacer (ITS) and RNA polymerase second largest subunit (rpb2) sequences, 170 isolates were chosen for further analyses. Sequences of the Alternaria major allergen gene (Alt a 1), endopolygalacturonase (endoPG), OPA10-2, and KOG1058 were also included in the phylogenetic analyses. Identification of secondary metabolites and metabolite profiling of the isolates were performed using high-performance liquid chromatography (HPLC)–high-resolution tandem mass spectrometry (HR-MS/MS). The multilocus phylogeny results revealed two distinct groups in grapevine, namely A. alternata and the A. arborescens species complex (AASC). Eight main metabolites were identified in all collected Alternaria isolates, regardless of their affiliation to the species and lineages. Multivariate analyses of untargeted metabolites found no clear separations; however, a partial least squares-discriminant analysis model was able to successfully discriminate between the metabolic datasets from isolates belonging to the AASC and A. alternata. By conducting univariate analysis based on the discriminant ability of the metabolites, we also identified several features exhibiting large and significant variation between A. alternata and the AASC. The separation of these groups may suggest functional differences, which may also play a role in the functioning of the plant microbiome. [ABSTRACT FROM AUTHOR]

In a consequence of global warming, grapevine trunk diseases (GTDs) have become a pertinent problem to viticulture, because endophytic fungi can turn necrotrophic upon host stress killing the plant. In Neofusicoccum parvum Bt‐67, plant‐derived ferulic acid makes the fungus release Fusicoccin aglycone triggering plant cell death. Now, we show that the absence of ferulic acid lets the fungus secrete 4‐hydroxyphenylacetic acid (4‐HPA), mimicking the effect of auxins on grapevine defence and facilitating fungal spread. Using Vitis suspension cells, we dissected the mode of action of 4‐HPA during defence triggered by the bacterial cell‐death elicitor, harpin. Early responses (cytoskeletal remodelling and calcium influx) are inhibited, as well as the expression of Stilbene Synthase 27 and phytoalexin accumulation. In contrast to other auxins, 4‐HPA quells transcripts for the auxin conjugating GRETCHEN HAGEN 3. We suggest that 4‐HPA is a key component of the endophytic phase of N. parvum Bt‐67 preventing host cell death. Therefore, our study paves the way to understand how GTDs regulate their latent phase for successful colonisation, before turning necrotrophic and killing the vines. Summary statement: During the asymptomatic phase of grapevine trunk diseases (GTDs), the aggressive Neofusicoccum parvum Bt‐67 secretes 4‐ hydroxyphenylacetic acid which has a similar structure to auxins. This metabolite suppressed plant defence mechanisms and downregulated transcripts of GH3, suggesting a key role in quelling the host response. [ABSTRACT FROM AUTHOR]

The three-cornered alfalfa hopper (TCAH), also known as Spissistilus festinus (Hemiptera: Membracidae), infests legumes and poses a threat to the grapevine industry by acting as a vector for grapevine red blotch virus (GRBV), which causes red blotch disease. Assessing TCAH flight capacity is key for understanding the risk of GRBV transmission. In this study, we examined the flight propensity and flight capacity of male and female TCAH using a flight mill apparatus under laboratory conditions. Our results revealed that sex and age had a significant effect on flight capacity. As insects aged, their flight capacity increased, with two-to-seven-day-old insects flying for shorter durations and covering shorter distances compared to mature insects (≥ eight days). Moreover, male insects exhibited significantly longer and farther flights compared to females, with an average flight capacity of 570.22 m for males and 239.57 m for females. Flight propensity, however, was not influenced by sex or age, as 88% (37/42) of males and 70% (31/44) of females engaged in flight. We observed that female TCAH were heavier and possessed larger wings than males. Nevertheless, wing loading and wing aspect ratio were similar between sexes, suggesting that morphological characteristics were not responsible for the observed differences in flight capacity. Our findings indicate that males have a greater capacity for GRBV dispersal compared to females, thereby providing a foundation for assessing the risk of GRBV spread facilitated by TCAH in vineyards. [ABSTRACT FROM AUTHOR]

In affected vineyards, the removal of individual diseased vines is recommended if disease incidence is less than 30%, while removing the entire vineyard is advised if disease incidence surpasses 30%. The virus has a single-stranded, circular DNA genome with 8 predicted bidirectional open reading frames (ORFs), 5 in the viral sense orientation and 3 in the complementary sense orientation. By 2012, a virus with a unique genome structure was identified in symptomatic grapevines [[2]], and by 2018, grapevine red blotch virus (GRBV) was confirmed as the causal agent of GRBD [[4]]. How does grapevine red blotch virus, the causative agent of GRBD, impact grapevine cultivatio... GRBV negatively affects grapevine cultivation and the wine industry. [Extracted from the article]

Plant diseases affect the quality and quantity of agricultural products and have an impact on food safety. These effects result in a loss of income in the production sectors which are particularly critical for developing countries. Visual inspection by subject matter experts is time-consuming, expensive and not scalable for large farms. As such, the automation of plant disease detection is a feasible solution to prevent losses in yield. Nowadays, one of the most popular approaches for this automation is to use drones. Though there are several articles published on the use of drones for plant disease detection, a systematic overview of these studies is lacking. To address this problem, a systematic literature review (SLR) on the use of drones for plant disease detection was undertaken and 38 primary studies were selected to answer research questions related to disease types, drone categories, stakeholders, machine learning tasks, data, techniques to support decision-making, agricultural product types and challenges. It was shown that the most common disease is blight; fungus is the most important pathogen and grape and watermelon are the most studied crops. The most used drone type is the quadcopter and the most applied machine learning task is classification. Color-infrared (CIR) images are the most preferred data used and field images are the main focus. The machine learning algorithm applied most is convolutional neural network (CNN). In addition, the challenges to pave the way for further research were provided. [ABSTRACT FROM AUTHOR]

The hook of Uncaria rhynchophylla is an important external phenotype representing the quality of Gou-Teng. The hook formation pattern of U. rhynchophylla displays a unique feature that solitary hook and opposite hooks alternately occur in the leaf axils forming a liner series. The solitary hook only grows on the lower side of the leaf axil, resulting from the decline in the total yield of hooks. However, the reasons for solitary hook formation in U. rhynchophylla are not clear. Therefore, a survey on the molecular mechanisms of solitary hook formation needs to be performed urgently. We obtained 250.67 million high-quality clean reads from the lower side of axillary stem segments (HS) and the upper side of axillary stem segments (HSCK) libraries. We detected 42 DEGs (differentially expressed genes) between HS and HSCK libraries; 11 were down-regulated, and 31 were up-regulated. Gene ontology functional classification of the DEGs indicated that they included two genes that encoded LAZY1 related to the regulation of polar auxin transport, two genes that encoded AUX/IAA and AP2/ERF related to plant hormone signaling transduction, and two genes that encoded F3H related to the flavone synthase activity. These six genes were associated with lateral polar auxin transport (PAT) regulation, and their expression level had a high correlation with the pattern of IAA distribution upon gravity stimulation. And the inhibition of solitary hook development was observed after treatment with N-1-naphthylphthalamic acid (NPA) or quercetin, which was known as the polar auxin inhibitor. The above findings might provide new information about the molecular mechanisms of regulation of lateral PAT in the axillary bud development process under gravity. [ABSTRACT FROM AUTHOR]

Here we present a study of the characterization and optimization of the production of trans-Resveratrol (t-R) in grape (Vitis vinifera cv. Gamay) cell cultures elicited with methyl jasmonate (MeJA) and dimethyl-β-cyclodextrin (DIMEB). The aim of this study was to determine the influence of a number of factors of the grapevine cell culture on t-R production level in 250 mL shaken flasks that would enable the better control of this bioproduction system when it is upscaled to a 2 L stirred bioreactor. The factors included the optimal growth phase for elicitation, the concentration of elicitors and of biomass, the order of addition of elicitors, and the illumination regime and ageing of cells. We found out that the optimal biomass density for the production of t-R was 19% (w/v) with an optimal ratio of 0.5 g DIMEB/g biomass. The most productive concentrations of the elicitors tested were 50 mM DIMEB and 100 µM MeJA, reaching maximum values of 4.18 mg·mL−1 and 16.3 mg·g biomass−1 of t-R concentration and specific production, respectively. We found that the order of elicitor addition matters since, as compared with the simultaneous addition of both elicitors, the addition of MeJA 48 h before DIMEB results in ca. 40% less t-R production, whilst there is no significant difference when MeJA is added 48 h after DIMEB. Upon upscaling, the better conditions tested for t-R production were aeration at 1.7 vol/vol/min without agitation, 24 °C, and 30 g·L−1 sucrose, achieving production rates similar to those obtained in shaken flasks. [ABSTRACT FROM AUTHOR]

Aim: This study evaluates the in vitro efficacy of 8-hydroxyquinoline (8HQ) derivatives in controlling the phytopathogenic fungus Phaeomoniella chlamydospora. Methods and results: The in vitro tests assessed the susceptibility to the minimum inhibitory concentration (MIC), checkerboard assay, mycelial growth (MG) inhibition, and EC50 determination. Among the seven agricultural fungicides tested, tebuconazole (TEB) displayed the lowest MIC, 1.01 µg mL−1, followed by captan (CAP), thiophanate methyl (TM), and mancozeb with MICs of 4.06, 5.46, and 10.62 µg mL−1, respectively. The 8HQ derivatives used in this study were clioquinol and PH 151 (PH) with MICs of 1.09 and 2.02 µg mL−1, respectively. PH associated with TEB and CAP showed synergism and inhibited 95.8% of MG at the highest dose. TEB inhibited 100% of MG at the three highest doses, while associated with PH exhibited the lowest EC50 (0.863 + 0.0381 µg mL−1). Conclusions: We concluded that the 8HQ derivatives tested controlled effectively the P. chlamydospora in vitro. PH associated with CAP and TEB exhibited a synergistic effect. The association between PH and TM was considered indifferent. Impact Statement: This study expands the list of active ingredients tested against P. chlamydospora, with the PH 151 and clioquinol derivatives being tested for the first time. The in vitro efficacy and synergistic action with other fungicides suggest a potential use as a grapevine wound protectant. This association makes it possible to reduce doses and increase the potency of both drugs, reducing the risk of resistance development and harm to humans and the environment. [ABSTRACT FROM AUTHOR]

The aim of this in vitro study was to examine the potential effect of functional food plant extracts, namely, extracts of flaxseed (Linum usitatissimum L.), chia (Salvia hispanica) and puncture vine (Tribulus terrestris L.), on basic mare ovarian cell functions and their response to the environmental contaminant toluene. Mare granulosa cells were incubated with and without toluene (0, 0.02, 0.2 or 2.0 μg/mL) in the presence or absence of flaxseed, chia and puncture vine extracts (10 μg/mL). Markers of cell proliferation (accumulation of proliferating cell nuclear antigen, PCNA) and apoptosis (accumulation of bax), viability (Trypan blue extrusion) and the release of progesterone (P), oxytocin (OT) and prostaglandin F 2 alpha (PGF) were measured. Toluene reduced all other measured parameters except OT release. All the tested plants were able to reduce cell viability and the release of P and PGF, but they did not influence other indexes. Moreover, flaxseed mitigated toluene action on ovarian cell proliferation, apoptosis, OT and PGF, whilst puncture vine prevented and inverted toluene action on P and PGF ourput. Chia extract did not modify toluene action on any parameter. On the other hand, toluene was able to promote the inhibitory action of flaxseed on cell viability and P release and to prevent the inhibitory action of all the plant extracts on PGF release. The present study (1) is the first demonstration, that flaxseed, chia and puncture vine can directly suppress mare ovarian cell functions, (2) shows that toluene can suppress basic ovarian cell functions and modify the reproductive effect of food plants and (3) demonstrates the ability of flaxseed and puncture vine, but not of chia, to prevent some toxic effect of toluene on mare ovarian cell functions. • Toluene can reduce viability, proliferation, apoptosis and hormones release by these cells and modify ovarian cell response to plants. • Flaxseed, chia and puncture vine can directly down-regulate viability, and progesterone and prostaglandin F release by mare ovarian cells. • Flaxseed and puncture vine, but not of chia can prevent the toxic effect of toluene on mare ovarian cell functions. [ABSTRACT FROM AUTHOR]

Simple Summary: Flavescence dorée is one of the most important diseases of grapevines. It is associated with phytoplasmas, pathogenic bacteria transmitted from vine to vine by the insect vector Scaphoideus titanus. The disease spread is limited by eradication of affected vines and control of S. titanus populations using insecticides. Recent studies highlighted that epidemic (transmitted by S. titanus) and non-epidemic phytoplasma strains can infect grapevines, and other insects and additional host plants are involved in Flavescence dorée epidemiology, increasing the risk of disease outbreaks. Thus, the objective of the present study was to identify the phytoplasma strains infecting grapevines in north-western Italy and investigate the presence of additional hosts. Only one epidemic phytoplasma strain was found in diseased grapevines. Moreover, this and other phytoplasma strains, reported as epidemic strains in previous studies, were found in several additional host plants and insect vectors. These findings reinforced the idea that Flavescence dorée epidemiological patterns are not limited to within vineyards, but they involve the entire ecosystems in which the vineyards are located. Flavescence dorée (FD) is the most important phytoplasma-associated disease of the grapevine yellows complex in Europe. Recent studies highlighted a great genetic diversity within FD phytoplasma (FDp) strains and demonstrated that their diffusion is not related exclusively to the pathosystem including Vitis vinifera L. and Scaphoideus titanus but involves additional vectors and reservoir plants. This study aimed to investigate FD epidemiology in north-western Italy, with a particular focus on FDp hosts. During field surveys, leaf samples were collected from symptomatic grapevines and other symptomless plant species, and insects were collected within and around vineyards. Phytoplasmas belonging to the ribosomal group 16SrV were detected and typed using nested-PCR-based amplification and nucleotide sequence analyses of the map gene. All symptomatic grapevines were found to be infected by the FDp genotype M54, prevalent in S. titanus and also identified in other known and newly reported hosts. Interestingly, other FDp strains (M38, M50, M51, M121) and FDp-related strains (M39, M43, M48), never detected in grapevines, were largely identified in several known and newly reported host plants and insects including S. titanus. Such evidence confirmed the complexity of FD ecology, expanding the knowledge on the range of FDp host plants putatively involved in the disease spread. [ABSTRACT FROM AUTHOR]

Phaeoacremonium minimum is an important esca and Petri disease pathogen that causes dieback of grapevines in South Africa. Little is known regarding the reproductive strategy of the pathogen. Sexual reproduction could lead to a better adaptation of the pathogen to disease management strategies by combining alleles through recombination. The study aimed to investigate the genetic diversity and recombination potential of eight populations in the Western Cape, from six commercial vineyards and two nursery rootstock mother blocks. This was achieved by developing and applying nine polymorphic microsatellites and mating-type-specific markers. Thirty-seven genotypes were identified from 295 isolates. Populations were characterised by the same dominant genotype (MLG20 occurring 65.43%), low genotypic diversity (H) and high numbers of clones (81.36% of dataset). However, genotypes from the same sampling sites were not closely related based on a minimum spanning network and had high molecular variation within populations (94%), suggesting that multiple introductions of different genotypes occurred over time. Significant linkage disequilibrium among loci (r̅d) further indicated a dominant asexual cycle, even though perithecia have been observed in these four populations. The two rootstock mother blocks had unique genotypes and genotypes shared with the vineyard populations. Propagation material obtained from infected rootstock mother blocks could lead to the spread of more genotypes to newly established vineyards. Based on our results, it is important to determine the health status of rootstock mother blocks. Management strategies must focus on reducing aerial inoculum to prevent repeated infections and further spread of P. minimum genotypes. [ABSTRACT FROM AUTHOR]

For a reliable test result to be obtained the following (external) controls should be included for each series of nucleic acid extraction and amplification of the target organism and target nucleic acid, respectively: Negative isolation control (NIC) to monitor contamination during nucleic acid extraction: nucleic acid extraction and subsequent amplification preferably of a sample of uninfected matrix, or if not available clean extraction buffer. Essential Procedural Information 3.1 Controls For a reliable test result to be obtained, the following (external) controls should be included for each series of nucleic acid extraction and amplification of the target organism and target nucleic acid, respectively Negative isolation control (NIC) to monitor contamination during nucleic acid extraction: nucleic acid extraction and subsequent amplification preferably of a sample of uninfected matrix or if not available clean extraction buffer. Inclusivity 100% evaluated on 55 target strains belonging to I X. fastidiosa i subsp. I fastidiosa i , I X. fastidiosa i subsp. I pauca i , I X. fastidiosa i subsp. I sandyi i , I X. fastidiosa i subsp. I multiplex i . A validation study with non-European I X. fastidiosa i strains (Harper et al., [56]) showed that the RST31/33 primer failed to detect the following American strains from grapes and oaks: I X. fastidiosa i , I Vitis vitifolia i , US (PD0001); I X. fastidiosa i , I V. vitifolia i , US (R. Almeida); I X. fastidiosa i , I Vitis rotundifolia i , US (C. Chang); I X. fastidiosa i , I Quercus laevis i , US (OAK0023); I X. fastidiosa i , I Quercus rubra i , US (OAK0024); I X. fastidiosa i , I Quercus rubra i , US (C. Chang). Inclusivity: 100% tested on 10 target strains ( I X. fastidiosa i subsp. I fastidiosa i , I X. fastidiosa i subsp. I pauca i , I X. fastidiosa i subsp. I sandyi i , I X. fastidiosa i subsp. I multiplex i ). [Extracted from the article]

Grapevine Trunk Diseases (GTDs) are major threats in Mediterranean countries, causing economic losses due to reduced grape yields and long-term vine productivity, as well as death of grapevines. A survey was conducted in Piedmont (Northern Italy) during 2021-2022 to investigate the species diversity and distribution of GTD pathogens in this important Italian wine region. Morphological and multilocus phylogenetic analyses (based on ITS, tef1, tub2, act and rpb2) identified species of Botryosphaeriaceae at high frequency, including Botryosphaeria dothidea, Diplodia mutila, Diplodia seriata and Neofusicoccum parvum. Other pathogens commonly associated with GTDs, including Eutypa lata, Fomitiporia mediterranea and Phaeomoniella chlamydospora, were also isolated. Less commonly isolated species included Neocucurbitaria juglandicola, Paraconiothyrium brasiliense, Seimatosporium vitis-viniferae and Truncatella angustata. Pathogenicity tests with two representative isolates of each species were carried out using one-year-old potted grapevine cuttings (‘Barbera’). All isolates (except N. juglandicola) caused brown wood necrotic vascular discolourations on inoculated plants and were successfully re-isolated. Effects of temperature on colony growth were also assessed. For all tested isolates there was no growth at 5°C, only four isolates (Botryosphaeriaceae) grew at 35°C, and optimum growth temperatures were between 20 and 25°C. This is the first record of Paraconiothyrium brasiliense and Neocucurbitaria juglandicola associated with symptomatic grapevines in Italy. [ABSTRACT FROM AUTHOR]

Despite studies associating Fusarium spp. with grapevine decline since late 1970s, no consensus has been reached regarding the roles these fungi play in grapevine health. Recent studies in British Columbia, Canada, assessed prevalence of grapevine trunk diseases (GTDs) in young and mature vineyards, and the presence of GTD fungi in ready-to-plant nursery material sold in Canada. This study characterized the Fusarium spp. isolated from grapevines in BC by sequencing part of the translation elongation factor 1-alpha (TEF1) gene, and carried out pathogenicity studies to determine whether Fusarium plays a role in grapevine decline. Fusarium spp. were isolated from 9.8% of samples collected from young vines (≤ 8-year-old), and 7.3% from mature vines (> 8-year-old), showing decline symptoms in commercial vineyards. Fusarium was also isolated from 43.9% of ready-to-plant dormant grapevines analyzed from four nurseries. Fusarium incidence varied between plants within the same nursery and between plants from the different nurseries. DNA sequences of TEF1 allowed identification of Fusarium oxysporum, F. proliferatum, F. ramigenum, and a Fusarium sp. Pathogenicity studies were conducted in 1-year-old dormant rooted ‘Chardonnay’ plants grafted onto ‘3309C’ rootstock, and treatments included: i) whole plant, ii) trimming of roots, iii) cut at rootstock basal ends, and iv) trimming of roots plus cut at rootstock basal ends. Plants were inoculated using standardized methods, and were then planted in a greenhouse. Fusarium was compared with Dactylonectria macrodidyma, D. pauciseptata and Ilyonectria liriodendri used as positive controls. The Fusarium spp. caused necroses in rootstock roots and basal ends that were similar to those caused by blackfoot fungi. Fusarium spp. and black-foot fungi reduced root and shoot dry weights when compared with non-inoculated controls, but no statistically significant differences were recorded for most treatments. This study is the first in Canada to identify Fusarium spp. from grapevines. Though Fusarium was common in these grapevines, pathogenicity tests suggest that the identified Fusarium spp. were weakly pathogenic to ‘3309C’ rootstock grapevines. [ABSTRACT FROM AUTHOR]

Eutypa dieback of grapevine is a trunk disease that affects vineyard productivity. Wood symptoms of this disease develop consistently in greenhouse-grown plants, after inoculation of woody stems with the causal fungus Eutypa lata. Wood symptoms are a common measure of host cultivar resistance and E. lata isolate virulence. Leaf symptoms of the disease also develop in the greenhouse, although reports of low correlations between severity of wood and leaf symptoms (for some cultivars and isolates) indicate that a definitive procedure is required for evaluating cultivar resistance. Three ‘phenotyping assays’, replicated with two E. lata isolates (BX1-10 and M14), were assessed for quantifying resistance of a set of Vitis vinifera cultivars (‘Black Corinth’, ‘Carignane’, ‘Husseine’, ‘Merlot’, ‘Muscat Hamburg’, ‘Palomino’, ‘Peloursin’, ‘Primitivo’, and ‘Thompson Seedless’). The methods were: Assay 1 (leaf and woodystem symptoms measured 1 year post-inoculation on plants propagated from rooted, dormant cuttings); Assay 2 (green stem symptoms measured 4 months post-inoculation on plants propagated from rooted, green cuttings); and Assay 3 (leaf symptoms measured 6 weeks post-inoculation on plants propagated from rooted, dormant cuttings). High rates of mortality among some cultivars (‘Merlot’) in Assay 3 confounded results based on leaf symptoms. Results from Assays 1 and 2 were more consistent with each other, especially for the most resistant cultivars [‘Merlot’ and ‘Primitivo’ (aka ‘Zinfandel’)]’, than they were for these cultivars in Assay 3. Compared to resistant cultivars, there was more variation in the most susceptible cultivar, including ‘Black Corinth’, ‘Carignane’, ‘Husseine’, and ‘Thompson Seedless’, regardless of the assay. Assay 1 with isolate BX1-10 was the most repeatable and provided data on wood and leaf symptoms for cultivar comparisons. Assay 2 was the most rapid, and gave results similar to those from Assay 1. Assay 2 also accommodated germplasm that can only be propagated from green cuttings. [ABSTRACT FROM AUTHOR]

Black foot is a serious soilborne fungal disease causing decline of young grapevines. Affected plants show brown to dark streaks developing from the rootstock bases, wood necroses at trunk bases, sunken necrotic lesions on roots, and reduced root biomass. Several fungi, commonly known as Cylindrocarpon-like asexual morphs, have been associated with black foot. Nursery vines are infected during rooting in propagation processes, which is important for dissemination of the pathogens. Species associated with black foot in nursery vines produced in Uruguay were characterized by molecular, phenotypical and pathogenicity studies. From 2017 to 2019, 181 rooted vines grafted onto ‘1103P’, ‘SO4’, ‘101-14’, ‘3309C’ or ‘Gravesac’ rootstocks were sampled, and 71 Cylindrocarpon-like fungal isolates were recovered from rootstock tissues (basal ends and roots). Based on multi-gene phylogenetic analyses of HIS3, TEF and TUB2, and supported by phenotypical characterization, five species of Dactylonectria and Ilyonoectria were identified, with D. macrodidyma being the most prevalent followed by D. novozelandica, D. torresensis, D. palmicola and I. liriodendri. Four Ilyonectria isolates could not be identified to species level. Isolate pathogenicity was assessed using healthy rooted ‘Gravesac’ plants. After three months, isolates of all species infected the plants, causing necrotic lesions on roots and reducing root biomass. On average, 39% of ready-to-plant nursery vines were affected by black foot, emphasizing the need to develop integrated management to reduce black foot incidence in Uruguayan grapevine nurseries, based on studies under local conditions. [ABSTRACT FROM AUTHOR]

Good health of grapevine plants is important for productivity and sustainability of newly established vineyards, and accurate detection of bacterial and fungal pathogens is a prerequisite for managing the diseases they cause in nurseries. This study screened marketable, bare-rooted grapevine plants, obtained from different geographical regions of Türkiye, for fungal pathogens associated with grapevine trunk diseases (GTDs). In 2021, 43 grapevine nurseries located in eight provinces were surveyed to reveal the status of GTD pathogens on asymptomatic marketable plants. Fungal pathogens isolated from the roots and basal parts of asymptomatic dormant grapevines were identified using with morphological characteristics and molecular markers, and were subjected to pathogenicity tests. Six species; Cytospora viticola, Diaporthe ampelina, Diplodia seriata, Lasiodiplodia brasiliensis, Neofusicoccum parvum, and Truncatella angustata (associated with dieback), and six species; Cadophora ferruginea, Cadophora luteo-olivacea, Cadophora malorum, Phaeoacremonium minimum, Phaeoacremonium tuscanicum and Phaeomoniella chlamydospora (associated with Petri disease) were identified based on DNA sequencing of ITS and TEF1-α genes. GTD pathogens were detected in 12 and 14 of the 43 nurseries, respectively. Pathogenicity tests on 1103P vines revealed that all species were pathogenic (N. parvum and C. luteo-olivacea being the most virulent), and caused significant wood necroses when compared to non-inoculated experimental controls. This is the first report of C. ferruginea, C. malorum, L. brasiliensis, and P. tuscanicum associated with GTDs in Türkiye. [ABSTRACT FROM AUTHOR]