Fabiola Matarese

Biocontrol of Fusarium head blight: interactions between Trichoderma and mycotoxigenic Fusarium

Fusarium head blight (FHB) is a re-emerging wheat disease that causes extensive damage through direct losses in yield and quality due to the presence of damaged Fusarium kernels and their associated mycotoxins such as the trichothecene deoxynivalenol (DON). Biological control, including the treatment of crop residues with antagonists, in order to reduce pathogen inoculum of FHB, holds considerable promise. Ten Trichoderma isolates, previously selected for their ability to grow in the presence of DON, were preliminarily investigated as potential antagonists against Fusarium culmorum and F. graminearum mycotoxigenic strains in plate confrontation assays. The three Trichoderma isolates showing antibiosis and mycoparasitism were evaluated for their capacity to inhibit DON production by F. graminearum and F. culmorum on two natural substrates. The expression of some chitinase-encoding genes by the two best resulting Trichoderma strains, during interaction with F. culmorum and F. graminearum, was monitored. All investigated genes from chitinase subgroups A, B and the new subgroup C responded to mycoparasitic conditions and were upregulated before contact and/or when in contact with the host. T. gamsii 6085, the best antagonist, was finally used in a competition test against F. culmorum and F. graminearum on natural substrates, using a qPCR approach to evaluate its effect on the pathogens growth and DON production in haulms and rice. This test confirmed the ability of T. gamsii 6085 to antagonize the pathogens on rice. On wheat haulms, an extreme oligotrophic environment, T. gamsii 6085 seemed to develop very poorly and the growth of both the pathogens was unaffected by the presence of the antagonist.

Expression of terpene synthase genes associated with the formation of volatiles in different organs of Vitis vinifera

Plants produce a plethora of volatile organic compounds (VOCs) which are important in determining the quality and nutraceutical properties of horticultural food products, including the taste and aroma of wine. Given that some of the most prevalent grape aroma constituents are terpenoids, we investigated the possible variations in the relative expression of terpene synthase (TPS) genes that depend on the organ. We thus analysed mature leaves, young leaves, stems, young stems, roots, rachis, tendrils, peduncles, bud flowers, flowers and berries of cv Moscato bianco in terms of their VOC content and the expression of 23 TPS genes. In terms of the volatile characterization of the organs by SPME/GC-MS analysis, flower buds and open flowers appeared to be clearly distinct from all the other organs analysed in terms of their high VOC concentration. Qualitatively detected VOCs clearly separated all the vegetative organs from flowers and berries, then the roots and rachis from other vegetative organs and flowers from berries, which confirms the specialization in volatile production among different organs. Our real-time RT-PCR results revealed that the majority of TPS genes analysed exhibited detectable transcripts in all the organs investigated, while only some were found to be expressed specifically in one or just a few organs. In most cases, we found that the known products of the in vitro assay of VvTPS enzymes corresponded well to the terpenes found in the organs in which the encoding gene was expressed, as in the case of (E)-β-caryophyllene synthases, α-terpineol synthase and α-farnesene synthase. In addition, we found groups of homologous TPS genes, such as (E)-β-caryophyllene and β-ocimene synthases, expressed distinctively in the various tissues. This thus confirmed the subfunctionalization events and a specialization on the basis of the organs in which they are mostly expressed.

Analysis of the expression of terpene synthase genes in relation to aroma content in two aromatic Vitis vinifera varieties

Grape (Vitis vinifera L.) flavour management in the vineyard requires knowledge of the derivation of individual flavour and aroma characteristics. Some of the most prevalent wine grape aroma constituents are terpenoids and this study represents a wide report about grape terpene synthase (TPS) gene transcript profiling in different tissues of two aromatic grapevine varieties, particularly flowers and developing berries, correlated with the accumulation patterns of free aroma compounds. All investigated genes belonging to the TPS-a and TPS-b subfamilies reached the highest expression in accordance with the peak of accumulation of the respective compounds. In the TPS-g subfamily, only one of the genes characterised for linalool synthases showed major transcript abundance in ripening berries, whereas the only geraniol synthase had a peak of expression in green berries and at the beginning of ripening, when geraniol concentration started to increase and overcome the linalool concentration. The genes identified in this study as being mainly responsible for linalool and geraniol synthesis during berry development, and the phenological phases in which they are mostly expressed, should be of interest to viticulturists and wine makers to improve decision making along the chain of production.

Management of postharvest grape withering to optimise the aroma of the final wine: A case study on Amarone

Amarone wine is different from regular dry wine due to the postharvest withering of Corvina, Corvinone and Rondinella grapes. Grapes were withered in a commercial facility with variability in terms of temperature and relative humidity (R.H.). Sugar content reached 230-240gL(-1) and 280gL(-1) at 20% and 30% mass loss, respectively. Most of VOCs (volatile organic compounds) decreased during withering but few VOCs increased during withering and we considered as markers; in Corvinone they were methylhexanoate, dimethylsuccinate, nerol, nonanoic acid, and benzyl alcohol; in Corvina, benzyl alcohol, isoamyl alcohol, 1-hexanol, p-cymen-8-ol, 2,3 pinanediol, 3-oxo-ionol and 3-methyl-1-pentanol, coumaran and damascenone; in Rondinella, hexanol, nonanoic acid, methyl vanillate, damascenone, 3-oxo-ionol, eugenol, p-cymen-8-ol, 2,3 pinanediol, coumaran and raspberry keton. Olfactive descriptors of the wines and the potential aroma of the combination of Corvina wine with the wines of the other two varieties at different percentages of mass loss are reported.

Physiological parameters and protective energy dissipation mechanisms expressed in the leaves of two Vitis vinifera L. genotypes under multiple summer stresses

Photosynthetic performances and energy dissipation mechanisms were evaluated on the anisohydric cv. Sangiovese and on the isohydric cv. Montepulciano (Vitis vinifera L.) under conditions of multiple summer stresses. Potted vines of both cultivars were maintained at 90% and 40% of maximum water availability from fruit-set to veraison. One week before veraison, at predawn and midday, main gas-exchange and chlorophyll fluorescence parameters, chlorophyll content, xanthophyll pool and cycle and catalase activity were evaluated. Under water deficit and elevated irradiance and temperature, contrary to cv. Montepulciano and despite a significant leaf water potential decrease, Sangioveses leaves kept their stomata more open and continued to assimilate CO2 while also showing higher water use efficiency. Under these environmental conditions, in comparison with the isohydric cv. Montepulciano, the protective mechanisms of energy dissipation exerted by the anisohydric cv. Sangiovese were: (i) higher stomatal conductance and thermoregulation linked to higher transpiration rate; (ii) greater ability at dissipating more efficiently the excess energy via the xanthophylls cycle activity (thermal dissipation) due to higher VAZ pool and greater increase of de-epoxidation activity.

Study of the terpene profile at harvest and during berry development of Vitis vinifera L. aromatic varieties Aleatico, Brachetto, Malvasia di Candia aromatica and Moscato bianco

BACKGROUND In this work, we evaluated the aromatic composition of berries at harvest and during the whole berry development of Aleatico, Brachetto, Malvasia di Candia aromatica and Moscato bianco grapevine varieties, which were cultivated in the same vineyard and under the same agricultural conditions. RESULTS Malvasia had a total concentration of aroma which was significantly higher than the other grapes that showed comparable amounts with each other. The class of monoterpenes was quantitatively predominant for all four grapes, in the free and in the most plentiful bound form. In Malvasia and Aleatico there was a high prevalence of geraniol derivatives throughout the entire berry development while in Brachetto and in Moscato there was a prevalence of linalool derivatives during the green phase and geraniol derivatives during ripening. CONCLUSION The study of the monoterpene profile allowed us to highlight similarities and differences among the four aromatic varieties and to present a hypothesis about their biosynthetic dynamics. This information is useful for further studies on gene functional characterisation and the regulation of these important berry pathways.

Influence of vineyard altitude on Glera grape ripening (Vitis vinifera L.): effects on aroma evolution and wine sensory profile

BACKGROUND Environmental factors have been acknowledged to greatly influence grape and wine aromas. Among them, the effect of altitude on grape aroma compounds has scarcely been debated in literature available to date. In the present study, we investigated the influence of altitude on grape composition and aroma evolution during ripening of Vitis vinifera L. cultivar Glera grown in Conegliano-Valdobbiadene DOCG area (Italy). RESULTS The site at highest altitude (380 m above sea level) was warmer than the lowest site (200 m above sea level) and, even with differences in temperature in the range 1.5-2 °C, the impact of the cultivation site on grape ripening and aroma accumulation and preservation was significant. The lowest site demonstrated slower grape ripening, and grapes at harvest accumulated lower amounts of all of the main classes of aroma compounds typical of the Glera variety. Wines produced from the highest site were preferred in tasting trials for their more patent floral notes and elegance. CONCLUSION Altitude strongly influences grape ripening evolution and flavour accumulation in the Glera grape, and this result accounts for the different styles in the sparkling wines subsequently produced. Moreover, the present study shows that aroma compound biosynthesis, particularly that of benzenoides, starts before véraison in Glera.

Distinct transcriptome responses to water limitation in isohydric and anisohydric grapevine cultivars

BackgroundGrapevine (Vitis vinifera L.) is an economically important crop with a wide geographical distribution, reflecting its ability to grow successfully in a range of climates. However, many vineyards are located in regions with seasonal drought, and these are often predicted to be global climate change hotspots. Climate change affects the entire physiology of grapevine, with strong effects on yield, wine quality and typicity, making it difficult to produce berries of optimal enological quality and consistent stability over the forthcoming decades.ResultsHere we investigated the reactions of two grapevine cultivars to water stress, the isohydric variety Montepulciano and the anisohydric variety Sangiovese, by examining physiological and molecular perturbations in the leaf and berry. A multidisciplinary approach was used to characterize the distinct stomatal behavior of the two cultivars and its impact on leaf and berry gene expression. Positive associations were found among the photosynthetic, physiological and transcriptional modifications, and candidate genes encoding master regulators of the water stress response were identified using an integrated approach based on the analysis of topological co-expression network properties. In particular, the genome-wide transcriptional study indicated that the isohydric behavior relies upon the following responses: i) faster transcriptome response after stress imposition; ii) faster abscisic acid-related gene modulation; iii) more rapid expression of heat shock protein (HSP) genes and iv) reversion of gene-expression profile at rewatering. Conversely, that reactive oxygen species (ROS)-scavenging enzymes, molecular chaperones and abiotic stress-related genes were induced earlier and more strongly in the anisohydric cultivar.ConclusionsOverall, the present work found original evidence of a molecular basis for the proposed classification between isohydric and anisohydric grapevine genotypes.

Effect of methyl jasmonate on the aroma of Sangiovese grapes and wines

Methyl jasmonate (MeJA) was applied in a vineyard on leaves and grape clusters of cv Sangiovese to test its ability to stimulate the production of aromas and identify the main genes involved in the biosynthetic pathways switched on by the elicitor. MeJA application led to a delay in grape technological maturity and a significant increase in the concentration of several berry aroma classes (about twice the total aroma: from around 3 to 6μg/g of berry). Of these, monoterpenes showed the most significant increase. An analysis of the expression of terpenoid biosynthesis genes confirmed that the MeJA application activated the related biosynthetic pathway. The expression of all the TPS genes analyzedwas higher in samples treated with MeJA. Also the wines produced by microvinification of Sangiovese treated and untreated grapes showed a rise in the aroma concentration as in berries, with an important impact on longevity and sensorial characters of wines.

Genotyping of Grapevine Varieties from Garfagnana (Northern Tuscany): Evidence of a Historical Center of Diversity

The aim of this investigation was to recover, characterize, and increase the value of local grapevine varieties from Garfagnana, a mountainous area situated in the north of Tuscany (located in central Italy). A total of 130 accessions (vines) were identified in old Garfagnana vineyards, characterized by Organisation Internationale de la Vigne et du Vin morphological-phenological and productive parameters, and genotyped with 14 microsatellite loci. The microsatellite analysis identified 50 genotypes. Some of these genotypes matched Tuscan genotypes, others corresponded to varieties cultivated in other Italian and European regions, and 18 appeared to be genotypes currently identified only in Garfagnana and presumably autochthonous to this area. Cluster and similarity analyses based on both microsatellite and morphology data indicated a clear grouping of the majority of the autochthonous genotypes from Garfagnana. A parentage analysis revealed that the Garfagnana autochthonous genotypes are highly first degree–related among each other, suggesting that Garfagnana is a distinct historical center of diversity of cultivated varieties. The data from all varieties have been entered into the Italian Vitis Database (www.vitisdb.it).