In ovulo embryo culture of stenospermocarpic grapes

Ovules of 14 seedless cultivars, collected 41-49 d after anthesis, were excised and in vitro cultured on 2 different media: NN + 1 µM GA3 + 10 µM IAA and NN + 1 µM GA3 + 20 µM IAA + 2 g/l activated charcoal. Plant development occurred at variable rates; the best percentages were found in Flame Seedless, Perlon, Imperatrice, Carina, Perlette and Ruby Seedless. Genotype resulted to be the main factor affecting ovule response to culture, but also the medium and the interaction genotype x medium influenced it. The addition of 2 g/l activated charcoal to the medium, tested on the cv. Perlette, and the type of added auxin (IBA, IAA, NAA), tested on the cvs Perlette and Sultanina, enhanced plantlet development

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

Somatic variants for seed and fruit set in grapevine

Background: Grapevine reproductive development has direct implications on yield. It also impacts on berry and wine quality by affecting traits like seedlessness, berry and bunch size, cluster compactness and berry skin to pulp ratio. Seasonal fluctuations in yield, fruit composition and wine attributes, which are largely driven by climatic factors, are major challenges for worldwide table grape and wine industry. Accordingly, a better understanding of reproductive processes such as gamete development, fertilization, seed and fruit set is of paramount relevance for managing yield and quality. With the aim of providing new insights into this field, we searched for clones with contrasting seed content in two germplasm collections. Results: We identified eight variant pairs that seemingly differ only in seed-related characteristics while showing identical genotype when tested with the GrapeReSeq_Illumina_20K_SNP_chip and several microsatellites. We performed multi-year observations on seed and fruit set deriving from different pollination treatments, with special emphasis on the pair composed by Sangiovese and its seedless variant locally named Corinto Nero. The pollen of Corinto Nero failed to germinate in vitro and gave poor berry set when used to pollinate other varieties. Most berries from both open- and cross-pollinated Corinto Nero inflorescences did not contain seeds. The genetic analysis of seedlings derived from occasional Corinto Nero normal seeds revealed that the few Corinto Nero functional gametes are mostly unreduced. Moreover, three genotypes, including Sangiovese and Corinto Nero, were unexpectedly found to develop fruits without pollen contribution and occasionally showed normal-like seeds. Five missense single nucleotide polymorphisms were identified between Corinto Nero and Sangiovese from transcriptomic data. Conclusions: Our observations allowed us to attribute a seedlessness type to some variants for which it was not documented in the literature. Interestingly, the VvAGL11 mutation responsible for Sultanina stenospermocarpy was also discovered in a seedless mutant of Gouais Blanc. We suggest that Corinto Nero parthenocarpy is driven by pollen and/or embryo sac defects, and both events likely arise from meiotic anomalies. The single nucleotide polymorphisms identified between Sangiovese and Corinto Nero are suitable for testing as traceability markers for propagated material and as functional candidates for the seedless phenotype

Whole-genome sequencing and SNV genotyping of 'Nebbiolo' (Vitis vinifera L.) clones

'Nebbiolo' (Vitis vinifera) is among the most ancient and prestigious wine grape varieties characterised by a wide genetic variability exhibited by a high number of clones (vegetatively propagated lines of selected mother plants). However, limited information is available for this cultivar at the molecular and genomic levels. The whole-genomes of three 'Nebbiolo' clones (CVT 71, CVT 185 and CVT 423) were re-sequenced and a de novo transcriptome assembly was produced. Important remarks about the genetic peculiarities of 'Nebbiolo' and its intra-varietal variability useful for clonal identification were reported. In particular, several varietal transcripts identified for the first time in 'Nebbiolo' were disease resistance genes and single-nucleotide variants (SNVs) identified in 'Nebbiolo', but not in other cultivars, were associated with genes involved in the stress response. Ten newly discovered SNVs were successfully employed to identify some periclinal chimeras and to classify 98 'Nebbiolo' clones in seven main genotypes, which resulted to be linked to the geographical origin of accessions. In addition, for the first time it was possible to discriminate some 'Nebbiolo' clones from the others

Gene Transfer and Modulation for the Production of Food with Enhanced Quali-Quantitative Values: Potentials, Promises and Achievements

U radu je dan pregled istraživanja i dostignuća u primjeni molekularnih alata što se temelje na transferu i modulaciji gena, tj. na smanjenju ekspresije (engl. knock-down) ili izbacivanju gena (engl. knock-out), a za proizvodnju veće količine hrane poboljšanih svojstava te dobivanje različitih hranjivih sastojaka. Istraženi su odabrani primjeri genetske manipulacije biljaka (biofortifikacija i uklanjanje alergena) i životinja (riba i stoke). Razmotrena su obećanja i dostignuća u primjeni molekularno-bioloških alata za proizvodnju dobara veće vrijednosti, između ostalog mlijeka, te njihov sveukupni utjecaj na društvo.We present an overview of the research and achievements of applications of molecular tools based on gene transfer and gene modulation (gene knock-down and knock-out), aimed at enhancing food production, improving food properties and producing various valuable compounds for human nutrition. Selected cases of genetically manipulated plants (biofortification and allergene silencing) and animals (fish and livestock) are examined. Promises and accomplishments are considered when giving topic examples of the potentials offered by some applications of molecular biology for obtaining goods, among them milk, with enhanced value, and of their impact on society at large