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

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

Soil tillage or herbicide applications are commonly used in agriculture for weed control. These measures may also represent a disturbance for soil microbial communities and their functions. However, the generality of response patterns of microbial communities and functions to disturbance have rarely been studied at large geographical scales. We investigated how a soil disturbance gradient (low, intermediate, high), realized by either tillage or herbicide application, affects diversity and composition of soil bacterial and fungal communities as well as soil functions in vineyards across five European countries. Microbial alpha-diversity metrics responded to soil disturbance sporadically, but inconsistently across countries. Increasing soil disturbance changed soil microbial community composition at the European level. However, the effects of soil disturbance on the variation of microbial communities were smaller compared to the effects of location and soil covariates. Microbial respiration was consistently impaired by soil disturbance, while effects on decomposition of organic substrates were inconsistent and showed positive and negative responses depending on the respective country. Therefore, we conclude that it is difficult to extrapolate results from one locality to others because microbial communities and environmental conditions vary strongly over larger geographical scales. [ABSTRACT FROM AUTHOR]

Berry shrivel (BS) is one of the prominent and still unresolved ripening physiological disorders in grapevine. The causes of BS are unclear, and previous studies focused on the berry metabolism or histological studies, including cell viability staining in the rachis and berries of BS clusters. Herein, we studied the transcriptional modulation induced by BS in the rachis of pre-symptomatic and symptomatic clusters with a custom-made microarray qPCR in relation to a previous RNASeq study of BS berries. Gene set analysis of transcript expression in symptomatic rachis tissue determined suppression of cell wall biosynthesis, which could also be confirmed already in pre-symptomatic BS rachis by CESA8 qPCR analyses, while in BS berries, a high number of SWITCH genes were suppressed at veraison. Additionally, genes associated with the cell wall were differently affected by BS in berries. A high percentage of hydrolytic enzymes were induced in BS grapes in rachis and berries, while other groups such as, e.g., xyloglucan endotransglucosylase/hydrolase, were suppressed in BS rachis. In conclusion, we propose that modulated cell wall biosynthesis and cell wall assembly in pre-symptomatic BS rachis have potential consequences for cell wall strength and lead to a forced degradation of cell walls in symptomatic grape clusters. The similarity to sugar starvation transcriptional profiles provides a link to BS berries, which are low in sugar accumulation. However, further studies remain necessary to investigate the temporal and spatial coordination in both tissues. [ABSTRACT FROM AUTHOR]

Sustainable vineyard management in inter-rows may improve biodiversity and ecosystem service provision in landscapes with a high density of vineyards. The current work investigates the effect of three inter-row ground cover treatments (bare soil by tillage, alternating and complete vegetation cover) on carabid beetle communities and vine vitality, in relation to climatic, soil and landscape parameters. Pitfall traps were used to collect carabids in the spring and autumn of 2016 from nine Austrian vineyards, with all three ground cover treatments established in each vineyard. Additionally, grape berry samples were collected before harvest in order to determine juice quality parameters. Generalized linear mixed models revealed that complete vegetation cover, the most extensive vineyard inter-row management, decreased both carabid density and species richness. The variables hours of sunshine, vineyard cover at the landscape scale and mesofauna abundance had negative impacts on species richness. The largest differentiator of carabid communities was the sampling timepoint, and we observed clustering associated to vineyard manager, whereas ground cover treatment played no significant role. The importance of treatment on vine vitality parameters was low; however, complete vegetation cover was detrimental to vine vegetative growth and berry weight. On the basis of our results, we conclude that although community composition may be influenced by pedo-climatic conditions and landscape components, alternating vegetation cover is an option for maintaining both carabid diversity and high-quality berries in vineyards. [ABSTRACT FROM AUTHOR]

The successful parasitisation of a plant by a phytophagous insect is dependent on the delivery of effector molecules into the host. Sedentary gall forming insects, such as grape phylloxera (Daktulosphaira vitifoliaeFitch, Phylloxeridae), secrete multiple effectors into host plant tissues that alter or modulate the cellular and molecular environment to the benefit of the insect. The identification and characterisation of effector proteins will provide insight into the host-phylloxera interaction specifically the gall-induction processes and potential mechanisms of plant resistance. Using proteomic mass spectrometry and in-silico secretory prediction, 420 putative effectors were determined from the salivary glands or the root-feeding D. vitifoliae larvae reared on Teleki 5C (V. berlandieri x V. riparia). Among them, 170 conserved effectors were shared between D. vitifoliae and fourteen phytophagous insect species. Quantitative RT-PCR analysis of five conserved effector candidates (protein disulfide-isomerase, peroxidoredoxin, peroxidase and a carboxypeptidase) revealed that their gene expression decreased, when larvae were starved for 24 h, supporting their assignment as effector molecules. The D. vitifoliae effectors identified here represent a functionally diverse group, comprising both conserved and unique proteins that provide new insight into the D. vitifoliae–Vitis spp. interaction and the potential mechanisms by which D. vitifoliae establishes the feeding site, suppresses plant defences and modulates nutrient uptake. [ABSTRACT FROM AUTHOR]

Grapevine (Vitis vinifera L.) is the most economically important deciduous fruit crop in the world. Iron (Fe) is an essential micronutrient for plant development since its active form is involved in several biochemical processes, e.g., chlorophyll synthesis. The uptake of the elements depends on individual elements' interactions. Iron (Fe) nutrition of plants can be significantly affected by different nitrogen (N) forms through altering the uptake ratio of cations and anions, and changing rhizosphere pH. It is known, that most crop species grow best with access to nitrate (NO3 -) as well as ammonium (NH4 +) nitrogen, but little attention has been paid to changes in iron uptake under supply of different nitrogen (N) forms. The presented study aimed to decipher the specific interaction of different nitrogen (N) forms on Iron uptake of different grapevine rootstocks on the physiological as well as on the biochemical and molecular level. Four NH4 +: NO3 - ratios (0:1,1:5, 1:3, 1:1) were tested with a modified half-strength Hoagland solution with and without FeNa(III)-EDTA, summing up to eight treatments within a hydroponic system (Kick-Brauckmann, 7.5 L) under semi-controlled climatic glasshouse conditions in 2021. Rooted woody cuttings of the rootstocks Fercal (V.berlandieri x V. vinifera) and Couderc 3309 (V. riparia x V. rupestris) were used for the experiment. The results could differentiate iron deficiency effects, nitrogen form effects and rootstock effects. Biomass of leaves was negatively influenced by iron absent in both rootstocks with nitrate as only N source. This effect was observed for 3309C for all NH4 +: NO3 -ratios, while with Fercal the biomass of leaves increased with increasing amount of NH4 +. A similar trend was overserved for root biomass, promoting in Fercal with increased NH4 + amount and not response in 3309C. The efficiency of the photsystem II (Y(II)) decreased under iron deficient conditions in both rootstocks showing the strongest effect with only nitrate as N source especially with rootstock 3309C. Increasing ammonium levels in the nutrient solution lead to a higher pH reduction by the rootstocks probably enhancing the Fe2+ availability and uptake. The ferric chelate reductase (FCR) activity was specifically increased in Fercal under irondeficient conditions, while no effect was observed for 3309C in comparison to control plants. These first results of the study indicate that rootstocks differ in their preference on both the physiological and molecular level depending on the nitrogen form and in interaction with iron deficiency stress. In a next step the molecular mechanism will be analysed. [ABSTRACT FROM AUTHOR]

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Cyst nematodes induce specific syncytial feeding structures within the root which develop from an initial cell by successive incorporation of neighbouring cells through local cell wall dissolutions followed by hypertrophy of included cells. Expansins are known to induce cell wall relaxation and extension in acidic pH, and they are involved in many processes requiring wall modification from cell expansion to cell wall disassembly. We studied the expression pattern of tomato ( Lycopersicon esculentum L., cv. Money Maker) expansins during development of syncytia induced by the potato cyst nematode ( Globodera rostochiensis Woll.). Based on semi-quantitative reverse transcription–polymerase chain reaction, two expansin genes, LeEXPA4 and LeEXPA5, were selected for detailed examinations because their expression was either elevated in infected roots ( LeEXPA4) or specifically induced in the root upon nematode infection ( LeEXPA5). Both genes have distinct spatial and temporal expression patterns that may reflect their different roles in syncytium development. LeEXPA4 transcripts were localized predominantly in parenchymatous vascular cylinder cells surrounding syncytia. This finding suggests that LeEXPA4 might be involved in cell wall disassembly or relaxation, mediating syncytium expansion and/or development of conductive tissues. By contrast, LeEXPA5 transcripts were localized in enlarging syncytial elements. Similarly, in immunogold localization experiments, polyclonal antibodies localized the LeEXPA5 protein in cell walls of syncytial elements. This expression pattern suggests that LeEXPA5 gene is specifically involved in enlargement of cells incorporated into syncytium. [ABSTRACT FROM AUTHOR]

Simple Summary: Grape phylloxera is an American native insect pest that caused heavy damages to the vineyards worldwide since its spreading to wine regions since the 1850s. This insect, able to feed on leaves and roots, induces plant galls and manipulates the grapevine physiology leading to plant damage and may cause plant death. The most successful treatment was the use of mostly partially resistant rootstocks. The degree of resistance is affected by environment, grapevine management and the insect biotype. In this study, we analyse the interaction of insect biotypes feeding on particular host plants. Therefore we evaluated the gene expression of Phylloxera feeding on a susceptible host versus feeding on a rootstock in two different developmental stages. We discovered (mainly in advanced insect developmental stages) genes expressed in higher proportion in one insect compared to the other. These genes related to chemosensory; in plant physiology manipulation and root deformation and insect digestive traits may play a role in the plant-insect interaction determining plant resistance in response to the pest attack. Grape phylloxera is one of the most dangerous insect pests for worldwide viticulture. The leaf- and root-galling phylloxerid has been managed by grafting European grapevines onto American rootstock hybrids. Recent reports pinpoint the appearance of host-adapted biotypes, but information about the biomolecular characteristics underlying grape phylloxera biotypisation and its role in host performance is scarce. Using RNA-sequencing, we sequenced the transcriptome of two larval stages: L1 (probing) and L2-3 (feeding) larvae of two root-feeding grape phylloxera lineages feeding on the rootstock Teleki 5C (biotype C) and V. vinifera Riesling (biotype A). In total, 7501 differentially expressed genes (DEGs) were commonly modulated by the two biotypes. For the probing larvae, we found an increased number of DEGs functionally associated with insect chemoreception traits, such as odorant-binding proteins, chemosensory proteins, ionotropic, odorant, and gustatory receptors. The transcriptomic profile of feeding larvae was enriched with DEGs associated with the primary metabolism. Larvae feeding on the tolerant rootstock Teleki 5C exhibited higher numbers of plant defense suppression-associated DEGs than larvae feeding on the susceptible host. Based on the identified DEGs, we discuss their potential role for the compatible grape phylloxera–Vitis interaction belowground. This study was the first to compare the transcriptomes of two grape phylloxera lineages feeding on a tolerant and susceptible host, respectively, and to identify DEGs involved in the molecular interaction with these hosts. Our data provide a source for future studies on host adaptation mechanisms of grape phylloxera and help to elucidate grape phylloxera resistance further. [ABSTRACT FROM AUTHOR]

Cyst nematodes are economically important pests. As obligatory biotrophic endoparasites they invade host roots and induce formation of syncytia, structures that serve them as the only source of nutrients. During syncytium development, extensive cell wall modifications take place. Cell wall dissolution occurs during cell wall opening formation, cell walls expand during hypertrophy of syncytial elements and local cell wall synthesis leads to the thickening of syncytial cell wall and the formation of cell wall ingrowths. Numerous studies revealed that nematodes change expression of plant genes encoding cell wall modifying proteins including expansins. Expansins poses unique abilities to induce cell wall extension in acidic pH. Recently, we demonstrated that two alpha-expansin genes LeEXPA4 and LeEXPA5 are upregulated in tomato roots infected with potato cyst nematode (Globodera rostochiensis). In this addendum, we present the most recent results concerning involvement of plant cell wall modifying genes in syncytium development and discuss possible practical applications of this knowledge for developing plants with resistance against nematodes.