Giovanni Nieddu

NMR Analysis of Seven Selections of Vermentino Grape Berry: Metabolites Composition and Development

The goal of this work was to study via NMR the unaltered metabolic profile of Sardinian Vermentino grape berry. Seven selections of Vermentino were harvested from the same vineyard. Berries were stored and extracted following an unbiased extraction protocol. Extracts were analyzed to investigate variability in metabolites concentration as a function of the clone, the position of berries in the bunch or growing area within the vineyard. Quantitative NMR and statistical analysis (PCA, correlation analysis, Anova) of the experimental data point out that, among the investigated sources of variation, the position of the berries within the bunch mainly influences the metabolic profile of berries, while the metabolic profile does not seem to be significantly influenced by growing area and clone. Significant variability of the amino acids such as arginine, proline, and organic acids (malic and citric) characterizes the rapid rearrangements of the metabolic profile in response to environmental stimuli. Finally, an application is described on the analysis of metabolite variation throughout the physiological development of berries.

Analysis of diversity in the fruit tree genetic resources from a Mediterranean island

A large number of genotypes of different fruit tree species have been described in Sardinia, where the plant species have evolved by adaptation to the Mediterranean environment. In this work results are summarized of a long-term survey carried out in the island by the authors since the early 1980s. Ten fruit tree species have been surveyed and collections of the traditional varieties were established. Some are major staple crops such as olive and grape, others such as almond, cherry, plum, fig, apple and pear are nowadays less cultivated, and still others have been more recently introduced like apricot and cactus pear. Data on the level of inter and intra-species diversity are given, as illustrated by representative morphological traits. The results of isozymes and RAPD-PCR analysis on the species Ficus carica genotypes are included, to assess genetic relationship among accessions. Observations on composition, as well as on state of conservation of selected traditional varieties are reported, and the main causes of genetic erosion are listed.

Distinctive Anthocyanin Accumulation Responses to Temperature and Natural UV Radiation of Two Field-Grown Vitis vinifera L. Cultivars

The responses of two red grape varieties, Bovale Grande (syn. Carignan) and Cannonau (syn. Grenache), to temperature and natural UV radiation were studied in a three-years field experiment conducted in Sardinia (Italy), under Mediterranean climate conditions. Vines were covered with plastic films with different transmittances to UV radiation and compared to uncovered controls. Light intensity and spectral composition at the fruit zone were monitored and berry skin temperature was recorded from veraison. Total skin anthocyanin content (TSA) and composition indicated positive but inconsistent effects of natural UV light. Elevated temperatures induced alterations to a greater extent, decreasing TSA and increasing the degree of derivatives acylation. In Cannonau total soluble solids increases were not followed by increasing TSA as in Bovale Grande, due to both lower phenolic potential and higher sensitivity to permanence of high temperatures. Multi linear regression analysis tested the effects of different ranges of temperature as source of variation on anthocyanin accumulation patterns. To estimate the thermal time for anthocyanin accumulation, the use of normal heat hours model had benefit from the addition of predictor variables that take into account the permanence of high (>35 °C) and low (<15 °C and <17 °C) temperatures during ripening.

Preliminary Characterisation of Sardinian Red Grape Cultivars (Vitis vinifera L.) According to Their Phenolic Potential

Fourteen cultivars and clones, mainly selected from the island of Sardinia (Italy) and grown in a collection field, showed significant quantitative differences in phenolic potential. An extraction method designed to reproduce the winemaking process was used to determine the amounts of extractable polyphenols, anthocyanins, catechins and proanthocyanidins reactive to vanillin, and the proanthocyanidins in grape skins and seeds. The Sardinian cultivar Nieddera and the Spanish cultivar Graciano had the highest concentrations of extractable polyphenols, anthocyanins, catechins and proanthocyanidins reactive to vanillin. Four clones of the Cannonau cultivar (synonym Grenache) exhibited fairly high variability, with significant differences in berry and seed phenolic contents.

Deficit Irrigation Strategies in Vitis vinifera L. cv. Cannonau under Mediterranean Climate. Part I - Physiological Responses, Growth, Yield and Berry Composition

The effect of deficit irrigation strategies on physiological performance, growth, source:sink balance, water productivity and berry composition of field-grown grapevines of Vitis vinifera L. cv. Cannonau (syn. Grenache)/1103P were investigated in Sardinia, Italy, in 2009. In two of the treatments, both sides of the root system received 50% and 25% crop evapotranspiration (ETc), referred to as strategies DI50 and DI25, respectively. In the third treatment, which included partial root-zone drying (strategy PRD), ETc was set at 50%. All three treatments were compared to a full irrigation control (strategy FI), thus 100% ETc. No severe water stress was imposed from berry development onwards. Strategies DI25 and PRD induced higher stomatal closure and leaf water-use efficiency. A slightly higher net assimilation rate was recorded in FI before veraison. During ripening, leaf area decreased in DI50 and DI25, but lateral shoots continued to grow in FI and PRD. Yield and pruning weight were higher in FI, but in all the treatments the vines were source:sink balanced and supported ripening. Irrigation water productivity was higher in DI25, and no significant differences in yield or water productivity were observed between PRD and DI50 irrigated with a similar volume of water. Full irrigation produced berries with a significantly higher fresh and dry weight, lower °Brix and higher malic acid at harvest, while PRD berries weighed less and had less titratable acidity, lower phenol content and a higher pH. Total anthocyanin contents were consistently lower in DI25 and PRD, with highest values measured in DI50. The treatments showed different anthocyanin profiles, with a higher concentration of acylated anthocyanin in DI25 and PRD.

Deficit Irrigation Strategies in Vitis vinifera L. cv. Cannonau under Mediterranean Climate. Part II - Cluster Microclimate and Anthocyanin Accumulation Patterns

The contribution of light and thermal conditions to berry anthocyanin accumulation was investigated in grapevine Vitis vinifera L. cv. Cannonau/1103P subjected to different irrigation strategies in Sardinia, Italy in 2009. In two of the deficit irrigation treatments the root system received 50% and 25% crop evapotranspiration (ETc), referred to as DI50 and DI25, respectively. In the third treatment, which included partial root-zone drying (PRD), ETc was set at 50%. All three treatments were compared to a full irrigation control (FI), thus 100% ETc. Analysis of the thermal conditions during the growing season in 2009 provided evidence for a high frequency of elevated temperatures (> 30°C) during berry development. During ripening, the DI25 clusters intercepted significantly higher intensities (P < 0.01) of solar radiation, UV and PAR, particularly on the southeast canopy side, in comparison to FI and PRD. The analysis of berry temperatures in the DI treatments showed higher exposure to more than 35°C in the DI25 southeast berries. Thermal time for anthocyanin accumulation was computed for the DI50 and DI25 berries using normal heat hours (NHH). The patterns of daily NHH showed a reduction in thermal efficiency for anthocyanin accumulation during mid-ripening in the DI25 southeast berries compared to the DI50 ones. The higher temperatures at mid-ripening led to lower total anthocyanin contents in the DI25 berries. However, the coumaroyl-glucoside anthocyanin forms continued to increase in both the DI50 and DI25 berries, while a significant reduction in berry total contents of these forms was observed in FI and PRD. Both deficit irrigation and light conditions in the DI25 berries favoured the accumulation of more colourstable anthocyanins in the berry skin until harvest, namely p-coumaroyl-glucoside and acetyl-glucoside forms.

Pollen emission from olive trees and concentrations of airborne pollen in an urban area of North Sardinia

In this study the seasonal and daily variations in olive airborne pollen concentrations were measured in the atmosphere of Sassari (Italy) and the olive pollen emission was monitored in the countryside during the flowering period in 1995 and 1996, in order to detect the patterns of change in the atmosphere. The intensity and the timing of pollination was also studied in relation to phenological stages occurrence. In addition, the influence of the main meteorological parameters on pollen emission and airborne pollen dispersal in the city was assessed. Airborne pollen reached its highest concentration a few days before the peak of pollen emission in 1995 but several days after it in 1996 (6 days). Analysis of hourly concentrations shows that the maximum emission and dispersion recorded during the observation period occurred in the middle of the day. Significant regressions were found between hourly temperature and air humidity values and hourly pollen concentrations recorded in the olive grove for almost every day studied, indicating a negative correlation between humidity and pollen concentration and a positive correlation between pollen concentration and temperature. On the other hand, no significant correlation was observed between the meteorological parameters and pollen concentration recorded in the urban area.

Spatial analysis of gypsy moth populations in Sardinia using geostatistical and climate models

1 Spatial fluctuations of the Sardinian population of the gypsy moth Lymantria dispar (L.) (Lepidoptera: Lymantriidae) were characterized using geostatistical and climate models. Data on gypsy moth egg mass abundance recorded at 282 permanent monitoring sites from 1980 to 2004 were incorporated in a geographic information system with the vegetational, geomorphological and pedological features of the sites. 2 Statistical analyses revealed that the relative outbreak frequency was related to the predominant host tree, slope and elevation of the monitoring sites, whereas there was no correlation between outbreak frequency and exposure and soil type. 3 By using bioclimatic modelling, probability maps of gypsy moth outbreaks were generated. The model identified a probability surface with climatic conditions favourable to gypsy moth outbreaks and thus potentially subject to defoliation. The maps included 92 sites where outbreaks never occurred, suggesting that the Sardinian climate may not be a determinant factor for gypsy moth outbreaks. 4 The geostatistical method cokriging with outbreak frequency as a covariate was found to be the most suitable technique to estimate gypsy moth egg mass abundance. Semivariograms showed spatial correlation of egg mass abundance within the range 18.5–53 km. The results obtained were used to create regional gypsy moth distribution maps by cokriging, which demonstrated the outbreak foci and different infestation levels at each monitoring area. These results can help to delimit the treatment areas and develop rational gypsy moth management programmes.

A novel method for the determination of ascorbic acid and antioxidant capacity in Opuntia ficus indica using in vivo microdialysis

A simple and rapid method was developed for in vivo simultaneous determination of ascorbic-acid and antioxidant capacity in microdialysates from cladodes of Opuntia ficus-indica (L.) Miller. The method is verified in water-stressed plants, as compared with a well-watered test controls. The microdialysis probe construction and insertion procedure was specifically developed to minimise the tissue trauma of the plant and to obtain optimal dialysis performance. Microdialysis was performed using a flow rate of 3 μL/min and the samples were analysed by HPLC coupled to electrochemical detection of ascorbic-acid and DPPH-determined antioxidant capacity. Our data indicate exponential decay of the concentrations of the analysed compounds as a function of microdialysis sampling time. Water-stressed Opuntia show decreased ascorbic acid levels and increased the others antioxidants.

Sequence Polymorphisms and Structural Variations among Four Grapevine (Vitis vinifera L.) Cultivars Representing Sardinian Agriculture

The genetic diversity among grapevine (Vitis vinifera L.) cultivars that underlies differences in agronomic performance and wine quality reflects the accumulation of single nucleotide polymorphisms (SNPs) and small indels as well as larger genomic variations. A combination of high throughput sequencing and mapping against the grapevine reference genome allows the creation of comprehensive sequence variation maps. We used next generation sequencing and bioinformatics to generate an inventory of SNPs and small indels in four widely cultivated Sardinian grape cultivars (Bovale sardo, Cannonau, Carignano and Vermentino). More than 3,200,000 SNPs were identified with high statistical confidence. Some of the SNPs caused the appearance of premature stop codons and thus identified putative pseudogenes. The analysis of SNP distribution along chromosomes led to the identification of large genomic regions with uninterrupted series of homozygous SNPs. We used a digital comparative genomic hybridization approach to identify 6526 genomic regions with significant differences in copy number among the four cultivars compared to the reference sequence, including 81 regions shared between all four cultivars and 4953 specific to single cultivars (representing 1.2 and 75.9% of total copy number variation, respectively). Reads mapping at a distance that was not compatible with the insert size were used to identify a dataset of putative large deletions with cultivar Cannonau revealing the highest number. The analysis of genes mapping to these regions provided a list of candidates that may explain some of the phenotypic differences among the Bovale sardo, Cannonau, Carignano and Vermentino cultivars.