The Terroir Concept Interpreted through Grape Berry Metabolomics and Transcriptomics

Terroir refers to the combination of environmental factors that affect the characteristics of crops such as grapevine (Vitis vinifera) according to ...

University of Verona

The biochemical properties of PsbS protein, a nuclear-encoded Photosystem II subunit involved in the high energy quenching of chlorophyll fluorescence, have been studied using preparations purified from chloroplasts or obtained by overexpression in bacteria. Despite the homology with chlorophyll a/b/xanthophyll-binding proteins of the Lhc family, native PsbS protein does not show any detectable ability to bind chlorophylls or carotenoids in conditions in which Lhc proteins maintain full pigment binding. The recombinant protein, when refolded in vitro in the presence of purified pigments, neither binds chlorophylls nor xanthophylls, differently from the homologous proteins LHCII, CP26, and CP29 that refold into stable pigment-binding complexes. Thus, it is concluded that if PsbS is a pigment-binding protein in vivo, the binding mechanism must be different from that present in other Lhc proteins. Primary sequence analysis provides evidence for homology of PsbS helices I and III with the central 2-fold symmetric core of chlorophyll a/b-binding proteins. Moreover, a structural homology owed to the presence of acidic residues in each of the two lumen-exposed loops is found with the dicyclohexylcarbodiimide/Ca(2+)-binding domain of CP29. Consistently, both native and recombinant PsbS proteins showed [(14)C]dicyclohexylcarbodiimide binding, thus supporting a functional basis for its homology with CP29 on the lumen-exposed loops. This domain is suggested to be involved in sensing low luminal pH.

Biochemical properties of the PsbS subunit of photosystem II either purified from chloroplast or recombinant.

An anthocyanin-producing suspension culture of Daucus carota (L.) cv. Flakkese was used as model system to study secondary metabolite production in cell culture at the individual cell level. An approach was set up in which growth and production of anthocyanins were investigated using a combination of biochemical analysis, image (colour) analysis and in vivo imaging. This novel approach was used to segment the culture in different subpopulations and dissect the productive process in the cell culture grown under two different conditions, known to differ mainly for oxygen supply and mixing intensity (volume of 50 ml or 20 ml in 250 ml flasks). The 20 ml batch cultures gave a higher content and yield of anthocyanins, which depended on a complex balance between events that positively or negatively affected anthocyanin production. A model is proposed in which the different ability of cells to respond to environmental stimuli and stress depends on the different amount of anthocyanins accumulated within cells.

Image analysis and in vivo imaging as tools for investigation of productivity dynamics in anthocyanin-producing cell cultures of Daucus carota.

Plants produce a vast array of secondary metabolites, many of which have important biological properties in animals when consumed as part of the diet. Interestingly, although the activities and benefits of plant secondary metabolites in animals are well established, comparatively little is known about the endogenous functions of these compounds in plants. One way to investigate the role of secondary products in plants is to modify the secondary metabolome and investigate the impact of such modifications on the phenotype. We have designed a novel feeding approach using different hydroxycinnamic acids (HCAs) and the cyanidin precursor dihydroquercetin (DHQ) to modify the metabolome of carrot R3M suspension cells. This strategy increased the accumulation of specific metabolites in a predictable way, and provided novel insights into the carrot phenylpropanoid pathway, suggesting that (a) cells use HCA hexose esters as substrates in the biosynthetic pathway leading to the accumulation of the various HCA derivatives and (b) p-coumaric acid derivative levels play a key roles in the regulation the flux of HCAs along the pathway. Moreover, this rapid strategy for metabolome modification does not depend on the availability of molecular tools or knowledge and can therefore be applied to any plant species.

Carrot-specific features of the phenylpropanoid pathway identified by feeding cultured cells with defined intermediates.

The definition of the terroir concept is one of the most debated issues in oenology and viticulture. The dynamic interaction among diverse factors including the environment, the grapevine plant and the imposed viticultural techniques means that the wine produced in a given terroir is unique. However, there is an increasing interest to define and quantify the contribution of individual factors to a specific terroir objectively. Here, we characterized the metabolome and transcriptome of berries from a single clone of the Corvina variety cultivated in seven different vineyards, located in three macrozones, over a 3-year trial period.

Towards a scientific interpretation of the terroir concept: plasticity of the grape berry metabolome.

A metabolomic approach followed by principal components and partial least square analysis was used for investigating the effect of environmental factors on two Daucus carota L. cv. Flakkese cell lines (R3M and R4G), selected for their ability to produce anthocyanins in the light and the dark, respectively. A positive correlation between total anthocyanin, hydroxycinnamic and hydroxybenzoic acid accumulation was found in both lines. Furthermore, the experimental design and the combination of biochemical and statistical analyses allowed us to unravel complex relationships between environmental factors and phenylpropanoid composition. Among these, the induction by mechanical stress of overproduction of all anthocyanins, hydroxycinnamic and hydroxybenzoic acids except sinapic acid derivatives, whose accumulation was inhibited.

Metabolomics of Daucus carota cultured cell lines under stressing conditions reveals interactions between phenolic compounds.

The molecular events that characterize post-ripening grapevine berries have rarely been investigated and are poorly defined. In particular, a detailed definition of changes occurring during the postharvest dehydration, a process undertaken to make some particularly special wine styles, would be of great interest for both winemakers and plant biologists. We report an exhaustive survey of transcriptomic and metabolomic responses in berries representing six grapevine genotypes subjected to postharvest dehydration under identical controlled conditions. The modulation of phenylpropanoid metabolism clearly distinguished the behavior of genotypes with stilbene accumulation as the major metabolic event, although in genotypes that do not accumulate stilbenes the prevalent variation was the transient accumulation/depletion of anthocyanins and flavonols. The modulation of genes related to phenylpropanoid/stilbene metabolism highlighted the distinct metabolomic plasticity of genotypes, allowing the identification of candidate structural and regulatory genes. In addition to genotype-specific responses, a core set of genes was consistently modulated in all genotypes, representing the common features of berries undergoing dehydration and/or commencing senescence. This included genes controlling ethylene and auxin metabolism as well as genes involved in oxidative and osmotic stress, defense responses, anaerobic respiration, cell wall and carbohydrate metabolism. Several transcription factors were identified that may control these shared processes in the postharvest berry. Changes representing both common and genotype-specific responses to postharvest conditions shed light on the cellular processes taking place in harvested berries stored under dehydrating conditions for several months.

Stefania Ceoldo

Biotechnology Department

University of Verona

The Terroir Concept Interpreted through Grape Berry Metabolomics and Transcriptomics

Stefania Ceoldo

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Biotechnology Department

University of Verona

The Terroir Concept Interpreted through Grape Berry Metabolomics and Transcriptomics

Biotechnology Department