Gibberellin-like substances in root exudate of Vitis vinifera

Summary The levels of gibberellin (GA)-like activity in the root exudate of two seedless varieties of Vitis vinifera were examined by the barley endosperm assay, and compared with levels determined for other parts of the plant. That activity was due to GA-like substances was confirmed with dwarf-5 corn.When acidic, ethyl acetate soluble GA-like substances from sap and leaf extracts were chromatogrammed on thin layers of silica gel in chloroform/ethyl acetate/formic acid (50:50:1), activity moved to the same Rf as GA₃ and GA₁ (Rf 0.05–0.25). However, substances inhibitory to the barley endosperm assay were detected in both sap and leaf extracts. In the above solvent system the inhibitor(s) co-chromatogrammed with a GA₁/GA₇ mixture, and with abscisin II. The GA-like activity co-chromatogrammed with GA₃ on paper developed in isopropanol/ammonia/water (10:1:1).Calculations on the rate of gibberellin movement from the roots seemed to be compatible with levels of activity in the leaves, although these levels could also be a reflection of the general gibberellin level in the plant.The relevance of the findings is discussed.     

Seasonal dynamics of root system respiration inAtriplex confertifolia

Summary The seasonal dynamics of respiratory capacity in the root system ofAtriplex confertifolia was studied under field conditions. Respiratory capacity of the root system undergoes seasonal adjustments with peak capacity occurring in spring and minimum capacity occurring in late summer. At greater depths in the profile, the timing of peak and minimum capacities is progressively delayed.The timing of respiratory adjustments does not appear to be tightly correlated with soil moisture or soil temperature, and may reflect environmental pre-conditioning as well as an overall geneticallybased program to prolong the duration of root activity and minimize carbon requirements of the root system.     

Phases of Berry Growth in Vitis vinifera

The course of berry growth in Vitis vinifera has been interpreteddifferently by various authors. Divisions into two, three orfour phases have been postulated, though, in the latter cases,without any objective criteria for their delimitation. To clarifythis point, investigations were carried out with the cultivarsBacchus and Madeleine. Fresh and dry wt curves showed a double sigmoid course and threetransition points could be clearly defined. The central transitionpoint, occurring around 42 d after anthesis, may be definedas the change-over from the first to the second growth phase.Both the course of the fresh weight curve when plotted logarithmicallyand the relative growth rates argue against there being a phaseof slow growth at the beginning of the first growth phase. Indeed,the relative increase in fresh weight is maximal at the beginningof the first growth phase. The delimitation of a separate phase of little or no growthin the region of the transition from the first to the secondgrowth phase is not supported. The definitions of such phaseboundaries is arbitrary. The smaller the number of seeds perberry, the earlier is the first growth phase ended and the secondgrowth phase, including veraison, begun. During the first growth phase there is high cell division activity.The average area of an epidermal cell reached its minimum at8–11 d after anthesis, with a simultaneous strong increasein cell number. The maximal number of epidermal cells was attainedtowards the end of the first growth phase. The growth of the embryo showed no relation to the double-sigmoidalgrowth of the pericarp. Final embryo size was reached at 70–75d after anthesis. Seed d. wt, on the other hand, showed a biphasicincrease. The results presented here support the division of berry growthof V. vinifera into just two phases. Vitis vinifera L., grape vine, berry growth, growth phases     

Seasonal changes in the contribution of root respiration to total soil respiration in a cool-temperate deciduous forest

A trenching method was used to determine the contribution of root respiration to soil respiration. Soil respiration rates in a trenched plot (R _trench) and in a control plot (R _control) were measured from May 2000 to September 2001 by using an open-flow gas exchange system with an infrared gas analyser. The decomposition rate of dead roots (R _D) was estimated by using a root-bag method to correct the soil respiration measured from the trenched plots for the additional decaying root biomass. The soil respiration rates in the control plot increased from May (240–320 mg CO₂ m^–2 h^–1) to August (840–1150 mg CO₂ m^–2 h^–1) and then decreased during autumn (200–650 mg CO₂ m^–2 h^–1). The soil respiration rates in the trenched plot showed a similar pattern of seasonal change, but the rates were lower than in the control plot except during the 2 months following the trenching. Root respiration rate (R _r) and heterotrophic respiration rate (R _h) were estimated from R _control, R _trench, and R _D. We estimated that the contribution of R _r to total soil respiration in the growing season ranged from 27 to 71%. There was a significant relationship between R _h and soil temperature, whereas R _r had no significant correlation with soil temperature. The results suggest that the factors controlling the seasonal change of respiration differ between the two components of soil respiration, R _r and R _h.     

Seasonal and diurnal changes in photosynthesis and carbon partitioning in Vitis vinifera leaves in vines withand without fruit

In Vitis vinifera L. cv. Chardonnay maintained in a greenhouse,the maximum rate of photosynthesis, the measured rates of denovo sucrose and starch synthesis and the total leaf sucroseand starch contents were relatively constant throughout theperiod from April to July although the partitioning of newlyfixed carbon was modified in favour of sucrose synthesis half-waythrough the growing period. In these experimental conditions,no significant differences in these parameters were observedin plants from which the fruit had been removed in comparisonto the controls. In field-grown vines, photosynthesis rose toa maximum in the early morning consistent with the increasein ambient irradiance and then subsequently progressively decreased.This occurred every day. On clear days the mid-morning depressionin the rate of CO₂ assimilation was closely linked to decreasein stomatal conductance, but there was no correlation betweenthese parameters on days when the sun was overcast. There wasno correlation between leaf sucrose content and the depressionin photosynthesis. The calculated rate of non-cyclic electronflow did not decline in parallel with the mid-morning depression and the quantum efficiency of photosystem II was constantfor the whole of the period when the CO₂ assimilation was decreasing.The mid-morning depression of photosynthetic CO₂ assimilationwas related to both stomatal and non-stomatal effects. In neithersituation did it have any measurable feedback effect on theelectron transport rate or on the carbo hydrate contents ofthe leaves. Key words: Vitis vinifera L., source-sink interactions, sucrose, starch, photosynthesis     

Overwintering Stages of Meloidogyne incognita in Vitis vinifera

The overwintering of Meloidogyne incognita in and around Vitis vinifera cv. French Colombard roots was studied in a naturally infested vineyard at the Kearney Agricultural Center, in a growth chamber, in inoculated vines in microplots at the University of California, Davis, and in a greenhouse. Infected roots were sampled at intervals from onset of vine dormancy until plants accumulated about 800 degree days (DD - base 10 C). Embryogenesis within eggs, classified as less than or more than 16 cells and fully differentiated, and numbers of juveniles (second to fourth stage) and preovipositional and mature (egg-laying) adult stages in roots were determined. All stages were present at the onset of dormancy. Juveniles and immature females were not recovered during the dormant period. Mature females and eggs were always present in roots, although the number of mature females generally decreased with time after onset of dormancy. In contrast, in a greenhouse experiment that accumulated comparable DD without the host plant going through dormancy, the number of mature females increased. After bud break, the number of eggs per female increased and all nematode stages were found in host roots. Eggs in all stages of embryogenesis were observed at all times of sampling, indicating that females overwinter and are capable of laying eggs when conditions improve in the spring and need to be considered in nematode management decisions.     

Measurement of the potential across the sieve plates in Vitis vinifera

Summary The electrical potential difference across the sieve plates in the primary phloem of Vitis vinifera was measured by inserting micro-electrodes into the sieve-tubes. The values obtained ranged from 4–48 mV. The potential across the transverse walls of the phloem fibres was also determined and found to range from I–II mV. These results are discussed in relation to the theory of translocation based on electro-osmosis put forward independently by Fensom and Spanner.     

Genetic transformation of Vitis vinifera via organogenesis

Background  

Efficient transformation and regeneration methods are a priority for successful application of genetic engineering to vegetative propagated plants such as grape. The current methods for the production of transgenic grape plants are based on Agrobacterium-mediated transformation followed by regeneration from embryogenic callus. However, grape embryogenic calli are laborious to establish and the phenotype of the regenerated plants can be altered.     

Der Mitosezyklus der Zygotenkerne von Vitis vinifera

Bei Vitis vinifera cv. Weißer Burgunder und cv. Gewürztraminer wurde in zwei Jahren der Ablauf des Mitosezyklus der Zygoten untersucht. Anhand der Kernvolumina konnte festgestellt werden, daß die Befruchtung innerhalb von 24 Stunden nach dem Öffnen der Blüten (Bestäubung) stattfindet. Die G₁-Phase dauerte bis zum achten Tag nach dem Aufblühen. Die S-Phase wurde in vier Tagen und die G₂-Phase in sechs Tagen durchlaufen. Die Mitose, einschließlich des Zerstäubungsstadiums, dauerte drei Tage. Der Mitosezyklus der Zygotenkerne von Vitis vinifera benötigte also 20 Tage. Gegen Ende dieser Zeit wurde das Endosperm zellulär und konnte die Ernährung des sich entwickelnden Embryos übernehmen.     

Sugars and flowering in the grapevine (Vitis vinifera L.)

Sugars play an important role in grapevine flowering. This complex process from inflorescence initiation to fruit maturity takes two growing seasons. Currently, most of the available data concern the involvement of sugars as energy sources during the formation of reproductive structures from initiation of inflorescences during the summer of the first year, until flower opening during the following spring. Sugars devoted to the development of reproductive structures are supplied either by wood reserves or by photosynthesis in leaves or inflorescences, depending on the stage of development. Female meiosis appears to be a key point in the success of flower formation because (i) flowers are vulnerable at this stage and (ii) it corresponds in the whole plant to the transition between reserve mobilization from perennial organs (roots, trunk, and canes) towards efficient leaf photosynthesis. The perturbation of reserve replenishment during the previous year provokes perturbation in the development of inflorescences, whereas altering the photosynthetic sources affects the formation of flowers during the same year. In particular, a lack of sugar availability in flowers at female meiosis caused by various environmental or physiological fluctuations may lead to drastic flower abortion. Apart from energy, sugars also play roles as regulators of gene expression and as signal molecules that may be involved in stress responses. In the future, these two topics should be further investigated in the grapevine considering the sensitivity of flowers to environmental stresses at meiosis.     

A non-destructive determination of leaf chlorophyll in Vitis vinifera

A portable leaf greenness meter (SPAD-501) has been used to provide a rapid and non-destructive measurement of leaf chlorophyll in Vitis vinifera. Leaf extracted chlorophyll was related linearly to SPAD readings. It is suggested that separate linear equations should be developed for each cultivar so as to maximise the accuracy of estimating leaf chlorophyll content as a function of SPAD readings.     

Linkage disequilibrium in cultivated grapevine, Vitis vinifera L

We present here the first study of linkage disequilibrium (LD) in cultivated grapevine, Vitis vinifera L. subsp. vinifera (sativa), an outcrossing highly heterozygous perennial species. Our goal was to characterize the amount and pattern of LD at the scale of a few centiMorgans (cM) between 38 microsatellite loci located on five linkage groups, in order to assess its origin and potential applications. We used a core collection of 141 cultivars representing the diversity of the cultivated compartment. LD was evaluated with both independence tests and multilocus r ² , both on raw genotypic and reconstructed haplotypic data. Significant genotypic LD was found only within linkage groups, extending up to 16.8 cM. It appeared not to be influenced by the weak structure of the sample and seemed to be mainly of haplotypic origin. Significant haplotypic LD was found over 30 cM. Both genotypic and haplotypic r ² values declined to around 0.1 within 5–10 cM, suggesting a rather narrow genetic base of the cultivated compartment and limited recombination since domestication events. These first results open up a few application opportunities for association mapping of QTLs and marker assisted selection. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Molecular linkage maps of Vitis vinifera L. and Vitis riparia Mchx

Two linkage maps for grape (Vitis spp.) have been developed based on 81 F(1) plants derived from an interspecific cross between the wine cultivar Moscato bianco (Vitis vinifera L.) and a Vitis riparia Mchx. accession, a donor of pathogen resistance traits. The double pseudotest-cross mapping strategy was applied using three types of molecular markers. The efficiency of SSRs to anchor homologous linkage groups from different Vitis maps and the usefulness of AFLPs in saturating molecular linkage maps were evaluated. Moreover, the SSCP technique was developed based on sequence information in public databases concerning genes involved in flavonoid and stilbene biosynthesis. For the maternal genetic map a total of 338 markers were assembled in 20 linkage groups covering 1,639 cM, whereas 429 loci defined the 19 linkage groups of the paternal map which covers 1,518 cM. The identification of 14 linkage groups common to both maps was possible based on 21 SSR and 19 AFLP loci. The position of SSR loci in the maps presented here was consistent with other published mapping experiments in Vitis.     

葡萄细胞悬浮培养生产白藜芦醇

以巨峰葡萄果皮为外植体,在添加2.0 mg/L 6-苄基嘌呤（6-BA）和0.1 mg/L 2,4-二氯苯氧基（2,4-D）的B5培养基上诱导葡萄愈伤组织; 以50 g/L的初始接种量在添加1.0 mg/L 6-BA和0.05 mg/L 2,4-D的B5液体培养基上建立葡萄悬浮培养体系。在25～27 ℃下,摇床振荡暗培养（120～130 r/min）18 d后,葡萄细胞生物量和白藜芦醇含量达到最大值（16.17 g/L、95.69 μg/g干质量）。在培养第12天时,向培养基中添加100 μmol/L茉莉酸甲酯（MeJA）,经过6 d处理,细胞中白藜芦醇含量达235.73 μg/g干质量。     

Immunocharacterization of NADH-Glutamate Dehydrogenase from Vitis vinifera L

Rabbit antiserum was raised against NADH-glutamate dehydrogenase (GDH) isoenzyme 1, purified from leaves of Vitis vinifera L. cv Soultanina and its specificity was tested. This antiserum was used for immunocharacterization of the GDH from leaf, shoot, and root tissues. The antiserum recognized the seven isoenzymes of NADH-GDH and precipitated all the enzyme activity from the three tissues tested. Western blot following SDS-PAGE revealed the same protein band for the three tissues, with a molecular mass of 42.5 kilodaltons corresponding to NADH-GDH subunit. Results, based on the immunological studies, revealed that NADH-GDH from leaf, shoot, and root tissues are closely related proteins. Furthermore, addition of ammonium ions to the culture medium of in vitro grown explants resulted in a significant increase in NADH-GDH activity in root, shoot, and leaf tissues.     

Identification of the abscisic acid receptor VvPYL1 in Vitis vinifera

The phytohormone abscisic acid (ABA) plays a central role in many developmental processes and in responses to several abiotic stresses. Identification of the ABA receptor is a first step towards understanding ABA signalling. In this study, using homology analysis, we cloned three genes, named VvPYL1, VvPYL2 and VvPYL3, from Vitis vinifera. An isothermal titration calorimetry assay suggested that VvPYL1 could bind to ABA. A phosphatase activity assay demonstrated that VvPYL1 inhibits phosphatase activity of ABI1, a negative regulator of ABA signalling, in the presence of ABA. Subcellular localisation demonstrates that VvPYL1 is distributed in both the nucleus and cytosol, which is similar to the subcellular localisation of ABA receptors in Arabidopsis. We therefore conclude that VvPYL1 is an ABA receptor that modulates ABA signalling by inhibiting type 2C protein phosphatases (PP2Cs).     

Multiple loss-of-function 5-O-glucosyltransferase alleles revealed in Vitis vinifera,but not in other Vitis species

Key message

Wild and loss-of-function alleles of the 5 - O - glucosyltransferase gene responsible for synthesis of diglucoside anthocyanins in Vitis were characterized. The information aids marker development for tracking this gene in grape breeding.

Abstract

Anthocyanins in red grapes are present in two glycosylation states: monoglucoside (3-O-glucoside) and diglucoside (3, 5-di-O-glucoside). While monoglucoside anthocyanins are present in all pigmented grapes, diglucoside anthocyanins are rarely found in the cultivated grape species Vitis vinifera. Biochemically 3-O-glucoside anthocyanins can be converted into 3,5-di-O-glucoside anthocyanins by a 5-O-glucosyltransferase. In this study, we surveyed allelic variation of the 5-O-glucosyltransferase gene (5GT) in 70 V. vinifera ssp. vinifera cultivars, 52 V. vinifera ssp. sylvestris accessions, 23 Vitis hybrid grapes, and 22 accessions of seven other Vitis species. Eighteen 5GT alleles with apparent loss-of-function mutations, including seven premature stop codon mutations and six frameshift indel mutations, were discovered in V. vinifera, but not in the other Vitis species. A total of 36 5GT alleles without apparent loss-of-function mutations (W-type) were identified. These W-type alleles were predominantly present in wild Vitis species, although a few of them were also found in some V. vinifera accessions. We further evaluated some of these 5GT alleles in producing diglucoside anthocyanins by analyzing the content of diglucoside anthocyanins in a set of representative V. vinifera cultivars. Through haplotype network analysis we revealed that V. vinifera ssp. vinifera and its wild progenitor V. vinifera ssp. sylvestris shared many loss-of-function 5GT alleles and extensive divergence of the 5GT alleles was evident within V. vinifera. This work advances our understanding of the genetic diversity of 5GT and provides a molecular basis for future marker-assisted selection for improving this important wine quality trait.     

Epiphytic fungal community in Vitis vinifera of the Portuguese wine regions

In this work, fungi present in the grapevine's phyllosphere collected from the main demarcated wine regions of Portugal were identified, and their phylogenetic relationships were analysed. A total of 46 vine samples (leaves and berries) were collected from different parts of the country, being isolated a total of 117 fungal colonies that were identified to the genus level and sequenced in the following genetic regions: internal transcribed spacer region and 18S rRNA and β‐tubulin gene. Next, a phylogenetic tree reconstruction for each genetic region was built. The isolates retrieved from environmental samples belonged to the genera Alternaria (31%), Cladosporium (21%), Penicillium (19%), Aspergillus (7%) and Epicoccum (3%). No genetic signatures of exchange of genetic material were detected, and consequently, the reconstructed phylogenetic trees allowed to distinguish between these different species/genera. In the fungal composition of the Vitis vinifera phyllosphere, several potential pathogens were identified that can be associated with decreases in crop productivity. Knowledge of fungi identification and genetic diversity is pivotal for the development of more adequate crop management strategies. Furthermore, this information will provide guidelines for a more specific and wiser use of fungicides.

Significance and Impact of the Study

The knowledge on the composition of the phyllosphere microbial community is still limited, especially when fungi are concerned. These micro‐organisms not only play a crucial role in crop health and productivity but also interact with the winemaking process, determining the safety and quality of grape and grape‐derived products. The elucidation of the micro‐organisms present in the phyllosphere will have a notorious impact on plant breeding and protection programmes and disease management strategies, allowing a better control of pesticide applications.     

Prenyltransferase compartmentation in cells of Vitis vinifera cultivated in vitro

Two prenyltransferases were located in cell cultures of Vitis vinifera. A geranyl pyrophosphate synthase (EC 2.5.1.1) was associated with plastid-like membranes whereas a farnesyl pyrophosphate synthase (EC 2.5.1.10) was found to be soluble.