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1.  Regulation of flavonol content and composition in (Syrah×Pinot Noir) mature grapes: integration of transcriptional profiling and metabolic quantitative trait locus analyses 
Journal of Experimental Botany  2015;66(15):4441-4453.
Novel candidate genes for the fine regulation of flavonol content in ripe berries are identified through integration of transcriptional profiling and metabolic QTL analyses of a segregating grapevine progeny.
Flavonols are a ubiquitous class of flavonoids that accumulate preferentially in flowers and mature berries. Besides their photo-protective function, they play a fundamental role during winemaking, stabilizing the colour by co-pigmentation with anthocyanins and contributing to organoleptic characteristics. Although the general flavonol pathway has been genetically and biochemically elucidated, the genetic control of flavonol content and composition at harvest is still not clear. To this purpose, the grapes of 170 segregating F1 individuals from a ‘Syrah’×’Pinot Noir’ population were evaluated at the mature stage for the content of six flavonol aglycons in four seasons. Metabolic data in combination with genetic data enabled the identification of 16 mQTLs (metabolic quantitative trait loci). For the first time, major genetic control by the linkage group 2 (LG 2)/MYBA region on flavonol variation, in particular of tri-hydroxylated flavonols, is demonstrated. Moreover, seven regions specifically associated with the fine control of flavonol biosynthesis are identified. Gene expression profiling of two groups of individuals significantly divergent for their skin flavonol content identified a large set of differentially modulated transcripts. Among these, the transcripts coding for MYB and bZIP transcription factors, methyltranferases, and glucosyltranferases specific for flavonols, proteins, and factors belonging to the UV-B signalling pathway and co-localizing with the QTL regions are proposed as candidate genes for the fine regulation of flavonol content and composition in mature grapes.
PMCID: PMC4507773  PMID: 26071529
Berry; flavonols; candidate gene; metabolic profiling; microarray; quantitative trait loci; segregating population; Vitis vinifera.
2.  Target metabolite and gene transcription profiling during the development of superficial scald in apple (Malus x domestica Borkh) 
BMC Plant Biology  2014;14:193.
Fruit quality features resulting from ripening processes need to be preserved throughout storage for economical reasons. However, during this period several physiological disorders can occur, of which superficial scald is one of the most important, due to the development of large brown areas on the fruit skin surface.
This study examined the variation in polyphenolic content with the progress of superficial scald in apple, also with respect to 1-MCP, an ethylene competitor interacting with the hormone receptors and known to interfere with this etiology. The change in the accumulation of these metabolites was further correlated with the gene set involved in this pathway, together with two specific VOCs (Volatile Organic Compounds), α-farnesene and its oxidative form, 6-methyl-5-hepten-2-one. Metabolite profiling and qRT-PCR assay showed these volatiles are more heavily involved in the signalling system, while the browning coloration would seem to be due more to a specific accumulation of chlorogenic acid (as a consequence of the activation of MdPAL and MdC3H), and its further oxidation carried out by a polyphenol oxidase gene (MdPPO). In this physiological scenario, new evidence regarding the involvement of an anti-apoptotic regulatory mechanism for the compartmentation of this phenomenon in the skin alone was also hypothesized, as suggested by the expression profile of the MdDAD1, MdDND1 and MdLSD1 genes.
The results presented in this work represent a step forward in understanding the physiological mechanisms of superficial scald in apple, shedding light on the regulation of the specific physiological cascade.
PMCID: PMC4115171  PMID: 25038781
Malus domestica; Cold storage; Postharvest; Superficial scald; 1-MCP; Polyphenol oxidase; Polyphenols; α-farnesene; Programmed death cell
3.  An indirect assay for volatile compound production in yeast strains 
Scientific Reports  2014;4:3707.
Traditional flavor analysis relies on gas chromatography coupled to mass spectrometry (GC-MS) methods. Here we describe an indirect method coupling volatile compound formation to an ARO9-promoter-LacZ reporter gene. The resulting β-galactosidase activity correlated well with headspace solid phase micro extraction (HS/SPME) GC-MS data, particularly with respect to the formation of rose flavor. This tool enables large-scale screening of yeast strains and their progeny to identify the most flavor active strains.
PMCID: PMC3892184  PMID: 24424137
5.  MetaDB a Data Processing Workflow in Untargeted MS-Based Metabolomics Experiments 
Due to their sensitivity and speed, mass-spectrometry based analytical technologies are widely used to in metabolomics to characterize biological phenomena. To address issues like metadata organization, quality assessment, data processing, data storage, and, finally, submission to public repositories, bioinformatic pipelines of a non-interactive nature are often employed, complementing the interactive software used for initial inspection and visualization of the data. These pipelines often are created as open-source software allowing the complete and exhaustive documentation of each step, ensuring the reproducibility of the analysis of extensive and often expensive experiments. In this paper, we will review the major steps which constitute such a data processing pipeline, discussing them in the context of an open-source software for untargeted MS-based metabolomics experiments recently developed at our institute. The software has been developed by integrating our metaMS R package with a user-friendly web-based application written in Grails. MetaMS takes care of data pre-processing and annotation, while the interface deals with the creation of the sample lists, the organization of the data storage, and the generation of survey plots for quality assessment. Experimental and biological metadata are stored in the ISA-Tab format making the proposed pipeline fully integrated with the Metabolights framework.
PMCID: PMC4267269  PMID: 25566535
metabolomics; ISA-Tab; pipeline; data analysis; LC-MS; GC-MS
6.  A Multidisciplinary Approach Providing New Insight into Fruit Flesh Browning Physiology in Apple (Malus x domestica Borkh.) 
PLoS ONE  2013;8(10):e78004.
In terms of the quality of minimally processed fruit, flesh browning is fundamentally important in the development of an aesthetically unpleasant appearance, with consequent off-flavours. The development of browning depends on the enzymatic action of the polyphenol oxidase (PPO). In the ‘Golden Delicious’ apple genome ten PPO genes were initially identified and located on three main chromosomes (2, 5 and 10). Of these genes, one element in particular, here called Md-PPO, located on chromosome 10, was further investigated and genetically mapped in two apple progenies (‘Fuji x Pink Lady’ and ‘Golden Delicious x Braeburn’). Both linkage maps, made up of 481 and 608 markers respectively, were then employed to find QTL regions associated with fruit flesh browning, allowing the detection of 25 QTLs related to several browning parameters. These were distributed over six linkage groups with LOD values spanning from 3.08 to 4.99 and showed a rate of phenotypic variance from 26.1 to 38.6%. Anchoring of these intervals to the apple genome led to the identification of several genes involved in polyphenol synthesis and cell wall metabolism. Finally, the expression profile of two specific candidate genes, up and downstream of the polyphenolic pathway, namely phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO), provided insight into flesh browning physiology. Md-PPO was further analyzed and two haplotypes were characterised and associated with fruit flesh browning in apple.
PMCID: PMC3799748  PMID: 24205065
7.  Gibberellin metabolism in Vitis vinifera L. during bloom and fruit-set: functional characterization and evolution of grapevine gibberellin oxidases 
Journal of Experimental Botany  2013;64(14):4403-4419.
Gibberellins (GAs) are involved in the regulation of flowering and fruit-set in grapes (Vitis vinifera L.), but the molecular mechanisms behind this process are mostly unknown. In this work, the family of grapevine GA oxidases involved in the biosynthesis and deactivation of GAs was characterized. Six putative GA 20-oxidase (GA20ox), three GA 3-oxidase (GA3ox), and eight GA 2-oxidase (GA2ox) proteins, the latter further divided into five C19-GA 2ox and three C20-GA2ox proteins, were identified. Phylogenetic analyses suggest a common origin of the GA3ox and C19-GA2ox groups and challenge previous evolutionary models. In vitro analysis revealed that all GA3ox and GA20ox enzymes prefer substrates of the non-13-hydroxylation pathway. In addition, ectopic expression of GA2ox genes in Arabidopsis thaliana confirmed the activity of their encoded proteins in vivo. The results show that bioactive GA1 accumulates in opening grapevine flowers, whereas at later developmental stages only GA4 is detected in the setting fruit. By studying the expression pattern of the grapevine GA oxidase genes in different organs, and at different stages of flowering and fruit-set, it is proposed that the pool of bioactive GAs is controlled by a fine regulation of the abundance and localization of GA oxidase transcripts.
PMCID: PMC3808322  PMID: 24006417
Anthesis; fruit set; gibberellin 2β-hydroxylase; gibberellin 3β-hydroxylase; gibberellin metabolism; gibberellin oxidase; grapevine; inflorescence; Vitis vinifera.
8.  Ellagitannins from Rubus Berries for the Control of Gastric Inflammation: In Vitro and In Vivo Studies 
PLoS ONE  2013;8(8):e71762.
Ellagitannins have shown anti-inflammatory and anti-Helicobacter pylori properties; however, their anti-inflammatory activity at gastric level was not previously investigated. The aim of this research was to evaluate the effects of ellagitannins from Rubus berries on gastric inflammation. Ellagitannin enriched extracts (ETs) were prepared from Rubus fruticosus L. (blackberry) and Rubus idaeus L. (raspberry). The anti-inflammatory activity was tested on gastric cell line AGS stimulated by TNF-α and IL-1β for evaluating the effect on NF-kB driven transcription, nuclear translocation and IL-8 secretion. In vivo the protective effect of ellagitannins was evaluated in a rat model of ethanol-induced gastric lesions. Rats were treated orally for ten days with 20 mg/kg/day of ETs, and ethanol was given one hour before the sacrifice. Gastric mucosa was isolated and used for the determination of IL-8 release, NF-kB nuclear translocation, Trolox equivalents, superoxide dismutase and catalase activities. In vitro, ETs inhibited TNF-α induced NF-kB driven transcription (IC50: 0.67–1.73 µg/mL) and reduced TNF-α-induced NF-kB nuclear translocation (57%–67% at 2 µg/mL). ETs inhibited IL-8 secretion induced by TNF-α and IL-1β at low concentrations (IC50 range of 0.7–4 µg/mL). Sanguiin H-6 and lambertianin C, the major ETs present in the extracts, were found to be responsible, at least in part, for the effect of the mixtures. ETs of blackberry and raspberry decreased Ulcer Index by 88% and 75% respectively and protected from the ethanol induced oxidative stress in rats. CINC-1 (the rat homologue of IL-8) secretion in the gastric mucosa was reduced in the animals receiving blackberry and raspberry ETs. The effect of ETs on CINC-1 was associated to a decrease of NF-κB nuclear translocation in ETs treated animals. The results of the present study report for the first time the preventing effect of ETs in gastric inflammation and support for their use in dietary regimens against peptic ulcer.
PMCID: PMC3733869  PMID: 23940786
9.  A Metabolomic Approach to the Study of Wine Micro-Oxygenation 
PLoS ONE  2012;7(5):e37783.
Wine micro-oxygenation is a globally used treatment and its effects were studied here by analysing by untargeted LC-MS the wine metabolomic fingerprint. Eight different procedural variations, marked by the addition of oxygen (four levels) and iron (two levels) were applied to Sangiovese wine, before and after malolactic fermentation.
Data analysis using supervised and unsupervised multivariate methods highlighted some known candidate biomarkers, together with a number of metabolites which had never previously been considered as possible biomarkers for wine micro-oxygenation. Various pigments and tannins were identified among the known candidate biomarkers. Additional new information was obtained suggesting a correlation between oxygen doses and metal contents and changes in the concentration of primary metabolites such as arginine, proline, tryptophan and raffinose, and secondary metabolites such as succinic acid and xanthine. Based on these findings, new hypotheses regarding the formation and reactivity of wine pigment during micro-oxygenation have been proposed. This experiment highlights the feasibility of using unbiased, untargeted metabolomic fingerprinting to improve our understanding of wine chemistry.
PMCID: PMC3360592  PMID: 22662221
10.  Resistance to Plasmopara viticola in a grapevine segregating population is associated with stilbenoid accumulation and with specific host transcriptional responses 
BMC Plant Biology  2011;11:114.
Downy mildew, caused by the oomycete Plasmopara viticola, is a serious disease in Vitis vinifera, the most commonly cultivated grapevine species. Several wild Vitis species have instead been found to be resistant to this pathogen and have been used as a source to introgress resistance into a V. vinifera background. Stilbenoids represent the major phytoalexins in grapevine, and their toxicity is closely related to the specific compound. The aim of this study was to assess the resistance response to P. viticola of the Merzling × Teroldego cross by profiling the stilbenoid content of the leaves of an entire population and the transcriptome of resistant and susceptible individuals following infection.
A three-year analysis of the population's response to artificial inoculation showed that individuals were distributed in nine classes ranging from total resistance to total susceptibility. In addition, quantitative metabolite profiling of stilbenoids in the population, carried out using HPLC-DAD-MS, identified three distinct groups differing according to the concentrations present and the complexity of their profiles. The high producers were characterized by the presence of trans-resveratrol, trans-piceid, trans-pterostilbene and up to thirteen different viniferins, nine of them new in grapevine.
Accumulation of these compounds is consistent with a resistant phenotype and suggests that they may contribute to the resistance response.
A preliminary transcriptional study using cDNA-AFLP selected a set of genes modulated by the oomycete in a resistant genotype. The expression of this set of genes in resistant and susceptible genotypes of the progeny population was then assessed by comparative microarray analysis.
A group of 57 genes was found to be exclusively modulated in the resistant genotype suggesting that they are involved in the grapevine-P. viticola incompatible interaction. Functional annotation of these transcripts revealed that they belong to the categories defense response, photosynthesis, primary and secondary metabolism, signal transduction and transport.
This study reports the results of a combined metabolic and transcriptional profiling of a grapevine population segregating for resistance to P. viticola. Some resistant individuals were identified and further characterized at the molecular level. These results will be valuable to future grapevine breeding programs.
PMCID: PMC3170253  PMID: 21838877

Results 1-10 (10)