The grapevine is a difficult species for genetic studies due to the plant size and long life cycle. With the microvine, these limitations can be overcome thanks to its dwarf stature, continuous ...flowering, short juvenile phase and generation cycle. The advantages of the microvine allow scientists to undertake genetic studies 2-5 times more rapidly than the current situation with normal grapevines. However, the seeds obtained from microvine parents have a low germination rate, and therefore some approaches to improve seed germination are required. Four microvine lines (ML1, V19, Pico x FLB 225, and AB x ML1) and a classical grapevine variety (‘Syrah’ cl. 174) were experimented in embryo rescue experiments. To evaluate embryo germination rate during berry development, seeds were collected from four different berry developmental stages including 2 weeks before veraison (WBV), veraison, 3 and 6 weeks after veraison (WAV). For all microvine varieties, the age of seed or berry stage influenced the development of the embryos. The highest percentage of germinating embryos (100 %) and normal developed plantlets (100 %) were recorded at veraison stage followed by 2 WBV, 3 WAV and 6 WAV, respectively. In addition, growth and development of embryos derived from veraison berries were also faster than the other phases. This study concluded that veraison is the most suitable berry developmental stage for microvine embryo extraction and culture, whereas, the best stage for embryo rescue in ‘Syrah’ grapevine is 2 WBV. The information obtained from this experiment will be useful for microvine breeding programs and expand their germplasm base in the future.
Thanks to several Vitis vinifera backcrosses with an initial V. vinifera L. × V. rotundifolia (previously Muscadinia rotundifolia) interspecific cross, the MrRUN1/MrRPV1 locus (resistance to downy ...and powdery mildews) was introgressed in genotypes phenotypically close to V. vinifera varieties. To check the consequences of introgressing parts of the V. rotundifolia genome on gene expression during fruit development, we conducted a comparative RNA-seq study on single berries from different V. vinifera cultivars and V. vinifera × V. rotundifolia hybrids, including ‘G5’ and two derivative microvine lines, ‘MV102’ (resistant) and ‘MV32’ (susceptible) segregating for the MrRUN1/RPV1 locus. RNA-Seq profiles were analyzed on a comprehensive set of single berries from the end of the herbaceous plateau to the ripe stage. Pair-end reads were aligned both on V. vinifera PN40024.V4 reference genome, V. rotundifolia cv ‘Trayshed’ and cv ‘Carlos’, and to the few resistance genes from the original V. rotundifolia cv ‘52’ parent available at NCBI. Weighted Gene Co-expression Network Analysis (WGCNA) led to classifying the differentially expressed genes into 15 modules either preferentially correlated with resistance or berry phenology and composition. Resistance positively correlated transcripts predominantly mapped on the 4–5 Mb distal region of V. rotundifolia chromosome 12 beginning with the MrRUN1/MrRPV1 locus, while the negatively correlated ones mapped on the orthologous V. vinifera region, showing this large extremity of LG12 remained recalcitrant to internal recombination during the successive backcrosses. Some constitutively expressed V. rotundifolia genes were also observed at lower densities outside this region. Genes overexpressed in developing berries from resistant accessions, either introgressed from V. rotundifolia or triggered by these in the vinifera genome, spanned various functional groups, encompassing calcium signal transduction, hormone signaling, transcription factors, plant–pathogen-associated interactions, disease resistance proteins, ROS and phenylpropanoid biosynthesis. This transcriptomic insight provides a foundation for understanding the disease resistance inherent in these hybrid cultivars and suggests a constitutive expression of NIR NBS LRR triggering calcium signaling. Moreover, these results illustrate the magnitude of transcriptomic changes caused by the introgressed V. rotundifolia background in backcrossed hybrids, on a large number of functions largely exceeding the ones constitutively expressed in single resistant gene transformants.
Summary
The most economically important diseases of grapevine cultivation worldwide are caused by the fungal pathogen powdery mildew (Erysiphe necator syn. Uncinula necator) and the oomycete pathogen ...downy mildew (Plasmopara viticola). Currently, grapegrowers rely heavily on the use of agrochemicals to minimize the potentially devastating impact of these pathogens on grape yield and quality. The wild North American grapevine species Muscadinia rotundifolia was recognized as early as 1889 to be resistant to both powdery and downy mildew. We have now mapped resistance to these two mildew pathogens in M. rotundifolia to a single locus on chromosome 12 that contains a family of seven TIR‐NB‐LRR genes. We further demonstrate that two highly homologous (86% amino acid identity) members of this gene family confer strong resistance to these unrelated pathogens following genetic transformation into susceptible Vitis vinifera winegrape cultivars. These two genes, designated resistance to Uncinula necator (MrRUN1) and resistance to Plasmopara viticola (MrRPV1) are the first resistance genes to be cloned from a grapevine species. Both MrRUN1 and MrRPV1 were found to confer resistance to multiple powdery and downy mildew isolates from France, North America and Australia; however, a single powdery mildew isolate collected from the south‐eastern region of North America, to which M. rotundifolia is native, was capable of breaking MrRUN1‐mediated resistance. Comparisons of gene organization and coding sequences between M. rotundifolia and the cultivated grapevine V. vinifera at the MrRUN1/MrRPV1 locus revealed a high level of synteny, suggesting that the TIR‐NB‐LRR genes at this locus share a common ancestor.
A grapevine model system is described that is suitable for rapid forward and reverse genetic studies in small controlled environments. It is based on the Vvgai1 mutant allele that confers a dwarf ...stature, short generation cycles and continuous flowering ('microvine'). Black and white berry microvine genotypes were developed that can be transformed by Agrobacterium tumefaciens. Near-homozygous lines were created for efficient bi-allelic single nucleotide polymorphism (SNP) marker mapping and mutagenesis studies. A genetic mapping strategy based on picovine-derived microvine progeny populations was used to rapidly phenotype and map the flower sex and fleshless berry loci and identify a new lethal recessive locus, Vvlrl1. The microvine provides a unique model system for rapid genetic studies of grapevine by changing the perennial long life cycle of the plant to one with features and advantages similar to an annual plant.
Today’s viticulture faces the double challenge of reducing chemical input while adapting plant material to future climate conditions. Adopting fungus disease-tolerant varieties appears to be a ...long-term solution as long as they are performant under abiotic constraints, such as drought. This study aimed to study the effects of water deficit (WD) and characterise the different strategies adopted to cope with drought in six new fungus disease-tolerant varieties selected by INRAE compared to Syrah. During five consecutive seasons (2018 to 2022), a gradient of WD was applied in field conditions and monitored through vine predawn water potential measurements. Grape development was non-destructively tracked by imaging to determine the arrest of berry phloem unloading. All variables were collected at the single plant level. The impacts of WD on leaf gas exchange and intrinsic water use efficiency (WUEi), vegetative development and yield components were assessed, as well as the genotypic sensitivity to WD at the leaf, vegetative and reproductive levels. All variables were negatively impacted by WD, except for intrinsic water use efficiency and total non-structural carbohydrate concentrations. Genotypes were differently impacted by WD at the physiological and vegetative levels, while no genotype-dependent response was observed for most reproductive variables. Generally, genotypes with the highest potential (highest intercept) in a certain variable were also the most sensitive to water deficit (higher slope). The most sensitive genotype regarding physiological and reproductive variables was G5, which showed higher reductions in berry weight, photosynthesis and WUEi, contrasting with Syrah, 3159B and Floreal. In this study, we observed a diversity of strategies to cope with WD in the long term, where some genotypes opted to reduce most variables (G5 and Artaban) or to maintain functioning at higher levels (Syrah and 3176N). Others displayed mixed responses: either reducing vegetative growth more than yield (3159B) or vice-versa (G14).
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•Microvines guaiacol applications affect positively glycosylated aroma precursors.•The highest aroma impact after guaiacol application takes place at grape ripening stages.•Geraniol ...aglycone increment was 50 higher in treated Microvine fruits than control.•Guaiacol could be used as an elicitor to enhance the varietal aroma differentiation.
Previous field-grown experiments were carried out to study the effect of guaiacol spraying on the accumulation of aromatic compounds in grapevine fruits and their wines. It was shown that such treatments increase guaiacol glycoconjugates in leaves, shoots and fruits of Monastrell variety (Vitis vinifera), where there was a release of aglycone compounds during wine processing, modulating the final wine aromatic profile, not only in terms of guaiacol. However, it remains unstudied the effect on the glycosylated grape aroma precursors pool and the time of their maximum expression. Nowadays, it is possible to use a model vine known as Microvine (DRCF-Dwarf Rapid Cycling and Continuous Flowering) to perform original physiological studies on fruit development in controlled environments. Therefore, the aim of this work was to use the Microvine model to study the effect of guaiacol sprays in such fraction when applied at several fruit developmental stages. The applications were carried out from phenological stage BBCH 71 (fruit set: young fruits begin to swell, remains of flowers lost) to BBCH 85 (softening of berries), to reveal stage-specific responses of the accumulation of glycosylated aroma precursors at BBCH 89 (berries ripe for harvest). Here, it is showed that guaiacol is an elicitor of the accumulation of glycosylated aromatic compounds in the fruit, with a higher efficiency when applied during ripening stages. Especially significant was the geraniol accumulation increment which was fiftyfold higher than in control ones.
The increasing temperature associated with climate change impacts grapevine phenology and development with critical effects on grape yield and composition. Plant breeding has the potential to deliver ...new cultivars with stable yield and quality under warmer climate conditions, but this requires the identification of stable genetic determinants. This study tested the potentialities of the microvine to boost genetics in grapevine. A mapping population of 129 microvines derived from Picovine x Ugni Blanc flb, was genotyped with the Illumina® 18 K SNP (Single Nucleotide Polymorphism) chip. Forty-three vegetative and reproductive traits were phenotyped outdoors over four cropping cycles, and a subset of 22 traits over two cropping cycles in growth rooms with two contrasted temperatures, in order to map stable QTLs (Quantitative Trait Loci).
Ten stable QTLs for berry development and quality or leaf area were identified on the parental maps. A new major QTL explaining up to 44 % of total variance of berry weight was identified on chromosome 7 in Ugni Blanc flb, and co-localized with QTLs for seed number (up to 76 % total variance), major berry acids at green lag phase (up to 35 %), and other yield components (up to 25 %). In addition, a minor QTL for leaf area was found on chromosome 4 of the same parent. In contrast, only minor QTLs for berry acidity and leaf area could be found as moderately stable in Picovine. None of the transporters recently identified as mutated in low acidity apples or Cucurbits were included in the several hundreds of candidate genes underlying the above berry QTLs, which could be reduced to a few dozen candidate genes when a priori pertinent biological functions and organ specific expression were considered.
This study combining the use of microvine and a high throughput genotyping technology was innovative for grapevine genetics. It allowed the identification of 10 stable QTLs, including the first berry acidity QTLs reported so far in a Vitis vinifera intra-specific cross. Robustness of a set of QTLs was assessed with respect to temperature variation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Growing standardized plant material in controlled environment can facilitate the disentangling of the many impacts of climate change on grapevine production and quality. Microvine is a natural ...gibberellic acid insensitive mutant showing dwarfism, early and continuous flowering along the vegetative axes. It was initially proposed as a model for genetics. In this study, we questioned its suitability to facilitate and hasten the characterization of grapevine vegetative and reproductive growth and development patterns as wells as their responses to temperature elevation. A series of experiments were performed in the greenhouse and in growth chambers under either ‘standard’ (25/15°C days/night) or contrasted (from 22/12°C up to 30/25°C) thermal treatments for several weeks. Under ‘standard’ thermal condition, measured temporal patterns of leaf and berry growth were similar among several phytomers along the main axis allowing us to estimate temporal growth patterns from spatial distribution of organ size. These patterns were stable between independent experiments under similar thermal and irradiance conditions. When plants were exposed to contrasted thermal treatments, leaf emergence rate was found linearly related to average daily temperature allowing us to derive a thermal time based model of development. Under cool thermal conditions (22/12°C), the temporal evolution of biochemical parameters was similar to that classically found for grapevine. However, exposing plants to a + 8°C thermal treatment for 450 °Cd revealed strong alterations of the thermal time based developmental program with either acceleration (leaf and internode growth) or delay (flowering, sugar accumulation in berries), as well as major uncoupling between growth and storage in internodes. These results reveal the potential of Microvine to study grapevine responses to the many facets of climate change.
A rapid and sensitive method is presented for the determination of proline in grape berries. Following acidification with formic acid, proline is derivatized by heating at 100 °C for 15 min with 3% ...ninhydrin in dimethyl sulfoxide, and the absorbance, which is stable for at least 60 min, is read at 520 nm. The method was statistically validated in the concentration range from 2.5 to 15 mg/L, giving a repeatability and intermediate precision of generally <3%; linearity was determined using the lack of fit test. Results obtained with this method concurred (r = 0.99) with those obtained for the same samples on an amino acid analyzer. In terms of sample preparation, a simple dilution (5–20-fold) is required, and sugars, primary amino acids, and anthocyanins were demonstrated not to interfere, as the latter are bleached by ninhydrin under the experimental conditions. The method was applied to the study of proline accumulation in the fruits of microvines grown in phytotrons, and it was established that proline accumulation and concentrations closely resemble those of field-grown macrovines.
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