Grape microsatellite markers: Sizing of DNA alleles and genotype analysis of some grapevine cultivars

Capillary electrophoresis fluorescence-based technology and fragment sizing software were applied in order to type grape cultivars at microsatellite loci described by THOMAS and SCOTT (1993) and BOWERs et al. (1996). Whereas the data set was closely consistent with already known genotypes for the same cultivars, estimates of allele length differed remarkably from those reported. The pedigree of the Riesling crosses Bacchus, Optima, Müller-Thurgau, Scheurebe, Ehrenfelser, Kerner, Rotberger, Rieslaner and Incrocio Manzoni 6.0.13 were investigated, and Mendelian inheritance of automatically sized alleles proved to be easily scorable. In addition, ancient cultivars of the vine-growing area of Trentino were characterized at microsatellite loci. Genotypes of Marzemino, Teroldego, Lagrein, Lambrusco a foglia frastagliata and Groppello gentile proved to share more than 50 % of alleles

Selective use of wine yeast strains having different volatile phenols production

Among Saccharomyces cerevisiae wine yeasts, we found a high frequency of strains having the ability to decarboxylate 4-hydroxycinnamic acid and 3-methoxy-4-hydroxy-cinnamic acid. From Gewurztraminer juices fermented by S. cerevisiae wine strains with and without such character, we obtained wines with considerably different levels of volatile phenols and some interesting evidences of the likely precursors of 4-vinylguaiacol and 4-vinylphenol. The identification of yeast strains by electrophoretic karyotyping gave us the possibility of evaluating the effective contribution of the yeast in the organoleptic characteristic of Traminer wines associated with the concentration of such volatile phenols

Assessment of diversity and genetic structure is an essential step for effective use of grape germplasm collections

The economic importance of grapevine has driven significant efforts in genomics to accelerate the exploitation of Vitis resources for development of new cultivars. However, although a large number of clonally propagated accessions are maintained in grape germplasm collections worldwide, their use for crop improvement is limited by the scarcity of information on genetic diversity, population structure and proper phenotypic assessment. The identification of representative and manageable subset of accessions would facilitate access to the diversity available in large collections. The FEM grape germplasm resources (2273 accessions) were characterised using 22 common microsatellite loci and 384 single nucleotide polymorphisms (SNPs) to examine the structure of genetic diversity and to propose a core set of grape accessions representing the allelic diversity of the whole collection. Retention of the maximum genetic and phenotypic variability was tested for two genetic core collections and one larger core set established based on phenological records. These results can be combined to the definition of inter- and intraspecific levels of germplasm stratification, and make possible to design studies dissecting the genetic basis of agronomic and domestication-related trait

Genetic resources of Olea europaea L. in the Garda Trentino olive groves revealed by ancient trees genotyping and parentage analysis of drupe embryos

5openInternationalItalian coauthor/editorThe area of the Garda Lake within the Trentino province (north of Italy) is the northernmost part of Europe where the Mediterranean species Olea europaea L. is traditionally cultivated. ‘Casaliva’ is claimed as the main variety traditionally grown in the Garda Trentino area (GT) from which a world renowned niche extra virgin olive oil is produced. Since a dominant presence of ‘Casaliva’ would link the fruit set success and yield to a self-pollination compatibility system, a deep genetic survey of the olive tree population in the GT has been performed with the aim of establishing the actual varietal composition and of understanding from which pollen donor the ‘Casaliva’ olives originate. Forty-four dierent genetic profiles were observed among the 205 leaf samples collected from 106 ancient trees through the analysis of 20 nuclear microsatellite markers. The varietal composition in modern orchards was also explored and the vast majority of the additional 151 trees analyzed showed the same genotype as the ancient accessions of ‘Casaliva’. The results support the long historical link of ‘Casaliva’ with the GT and, besides a high varietal homogeneity, they also revealed the presence of olive genetic resources essential to fruit production. In fact, the parentage analysis of 550 embryos from drupes of ‘Casaliva’ evidenced that a cross-fertilization system is favored and a list of candidate cultivars most suitable as local pollinizers of ‘Casaliva’ was identified.openMoreno-Sanz, P.; Lombardo, L.; Lorenzi, S.; Michelotti, F.; Grando, M.S.Moreno-Sanz, P.; Lombardo, L.; Lorenzi, S.; Michelotti, F.; Grando, M.S

Functional effect of grapevine 1-deoxy-D-xylulose 5-phosphate synthase substitution K284N on Muscat flavour formation

Grape berries of Muscat cultivars (Vitis vinifera L.) contain high levels of monoterpenols and exhibit a distinct aroma related to this composition of volatiles. A structural gene of the plastidial methyl-erythritol-phosphate (MEP) pathway, 1-deoxy-D-xylulose 5-phosphate synthase (VvDXS), was recently suggested as a candidate gene for this trait, having been co-localized with a major quantitative trait locus for linalool, nerol, and geraniol concentrations in berries. In addition, a structured association study discovered a putative causal single nucleotide polymorphism (SNP) responsible for the substitution of a lysine with an asparagine at position 284 of the VvDXS protein, and this SNP was significantly associated with Muscat-flavoured varieties. The significance of this nucleotide difference was investigated by comparing the monoterpene profiles with the expression of VvDXS alleles throughout berry development in Moscato Bianco, a cultivar heterozygous for the SNP mutation. Although correlation was detected between the VvDXS transcript profile and the accumulation of free monoterpenol odorants, the modulation of VvDXS expression during berry development appears to be independent of nucleotide variation in the coding sequence. In order to assess how the non-synonymous mutation may enhance Muscat flavour, an in vitro characterization of enzyme isoforms was performed followed by in vivo overexpression of each VvDXS allele in tobacco. The results showed that the amino acid non-neutral substitution influences the enzyme kinetics by increasing the catalytic efficiency and also dramatically affects monoterpene levels in transgenic lines. These findings confirm a functional effect of the VvDXS gene polymorphism and may pave the way for metabolic engineering of terpenoid contents in grapevine

Identification of disease resistance-linked alleles in Vitis vinifera germplasm

Introgression of genetic resistance to fungal diseases from American and Asian Vitis species traditionally pursued in grape breeding programs, although facilitated by molecular tools, has an impact on wine quality that still slows down development of competitive varieties. A contribution to the genetic improvement of grapevines for resistance to pathogens may come from unexplored genetic resources of the Eurasian Vitis vinifera L. In the present study, a hundred grapevine accessions from Georgia, Armenia and Azerbaijan were genotyped with SSR markers linked to QTLs for resistance to downy and powdery mildew, and with 21 SSR markers widely used for genetic diversity and relationship analysis. Looking at population genetic structure, Armenian and Azerbaijani accessions fell within the same cluster and were included among the Central Asian grape varieties of a homogeneous dataset, while Georgian accessions formed a separate group. Pattern of SSR alleles flanking the locus Ren1 and associated with resistance to Erysiphe necator in 'Kishmish vatkana', 'Dzhandzhal kara' and other Central Asian cultivars were found in three varieties from the Azerbaijani population that reached very high scores when assessed for PM resistance

Linking monoterpenes and abiotic stress resistance in grapevines

Rising temperatures and ozone levels are among the most striking stressful phenomena of global climate changes, and they threaten plants that are unable to react rapidly and efficiently. Generic responses of plants to stresses include the production of excess reactive oxygen species (ROS). Excessive ROS accumulation can lead to extensive oxidation of important components such as nucleic acids, proteins and lipids which can further exacerbate ROS accumulation leading to programmed cell death. Although most studies on plant antioxidants have focused on non-volatile compounds, volatiles belonging to the isoprenoid family have been implicated in the protection against abiotic stresses, in particular thermal and oxidative stress whose frequency and extent is being exacerbated by ongoing global change and anthropogenic pollution. Historically, research has focused on isoprene, demonstrating that isoprene-emitting plants are more tolerant to ozone exposure and heat stress, reducing ROS accumulation. Yet, evidence is being compiled that shows other volatile isoprenoids may be involved in plant responses against abiotic stresses. Grapevines are not isoprene emitters but some varieties produce other volatile isoprenoids such as monoterpenes. We investigated photosynthesis and emission of volatile organic compounds upon heat stress in two Vitis vinifera cv. ‘Chardonnay’ clones differing only for a mutation in the DXS gene (2-C-methyl-D-erythritol 4-phosphate (MEP) pathway), regulating volatile isoprenoid biosynthesis. We showed that the mutation led to a strong increase in monoterpene emission upon heat stress. At the same time, maximum photochemical quantum yield (Fv/Fm ratio) of PSII was affected by the stress in the non-emitting clone while the monoterpene emitter showed a significant resilience, thus indicating a possible antioxidant role of monoterpenes in grapevine. Future mechanistic studies should focus on unveiling the actual mechanism responsible for such findings

Caracterização molecular de videiras de Santa Catarina por marcadores microssatélites

The objective of this work was to characterize the grape germplasm in Santa Catarina, Brazil, using microsatellite DNA markers (simple sequence repeats – SSR). The DNA samples were collected from leaves and shoots of accessions of public and private collections from the counties Urussanga, Nova Trento, Rodeio, São Joaquim, Campos Novos, Videira, and Água Doce. Ten SSR loci (VVS2, VVMD5, VVMD7, VVMD27, VrZAG62, VrZAG79, VVMD25, VVMD28, VVMD31, and VVMD32) were analysed by capillary electrophoresis. Molecular profiling was conducted for 190 grapevines (European, American, and hybrids), and 67 genotypes were obtained. The data were compared with each other and with those from the literature and from online databases, in order to identify varieties and discover cases of synonymy and homonymy. Forty molecular profiles corresponded to known varieties, while 27 genotypes were described for the first time. The existence of typical germplasm composed mainly of American and hybrid varieties is an important finding for local viticulture. Applications of the results rely on quality control and certification at the nursery level. Increasing precision in the characterization of grapevine genotypes may help breeding programs.O objetivo deste trabalho foi caracterizar a diversidade de videiras em Santa Catarina, por meio de marcadores moleculares microssatélites ("simple sequence repeats" – SSR). Amostras de DNA foram coletadas a partir de folhas e ramos de acessos de coleções de germoplasma públicas e privadas, nos municípios de Urussanga, Nova Trento, Rodeio, São Joaquim, Campos Novos, Videira e Água Doce. Dez loci SSR (VVS2, VVMD5, VVMD7, VVMD27, VrZAG62, VrZAG79, VVMD25, VVMD28, VVMD31 e VVMD32) foram analisados por eletroforese capilar. Foram produzidos perfis moleculares de 190 acessos de videira (europeus, americanos e híbridos), e 67 genótipos foram individualizados. Os dados foram comparados entre si e com aqueles disponíveis em literatura e em bancos de dados online, para a identificação de correspondências e casos de sinonímia e homonímia. Quarenta perfis moleculares corresponderam a variedades conhecidas, e 27 genótipos foram descritos pela primeira vez. A existência de um germoplasma típico, composto principalmente de variedades americanas e híbridas, é um fator importante para a viticultura local. A aplicação desses resultados poderá contribuir para o controle de qualidade e a certificação de mudas. Além disso, aumentar a precisão no que tange à caracterização genética da videira, auxiliará os programas de melhoramento genético