Antonio Pompeiano

Volatile organic compounds in truffle ( Tuber magnatum Pico): comparison of samples from different regions of Italy and from different seasons

In this paper volatile organic compounds (VOCs) from Tuber magnatum fruiting bodies were analyzed using a PTR-TOF-MS instrument. The aim was to characterize the VOCs profile of the fruiting bodies and identify if any VOCs were specific to a season and geographical areas. Multiple factorial analysis (MFA) was carried out on the signals obtained by MS. Experiments using ITS region sequencing proved that the T. magnatum life cycle includes the formation of fruiting bodies at two different times of the year. The VOCs profiles diverge when different seasonal and geographical productions are considered. Using PTR-TOF-MS, compounds present at levels as low pptv were detected. This made it possible to determine both the origin of fruiting bodies (Alba and San Miniato) and the two biological phases of fruiting bodies formation in San Miniato truffles.In this paper volatile organic compounds (VOCs) from Tuber magnatum fruiting bodies were analyzed using a PTR-TOF-MS instrument. The aim was to characterize the VOCs profile of the fruiting bodies and identify if any VOCs were specific to a season and geographical areas. Multiple factorial analysis (MFA) was carried out on the signals obtained by MS. Experiments using ITS region sequencing proved that the T. magnatum life cycle includes the formation of fruiting bodies at two different times of the year. The VOCs profiles diverge when different seasonal and geographical productions are considered. Using PTR-TOF-MS, compounds present at levels as low pptv were detected. This made it possible to determine both the origin of fruiting bodies (Alba and San Miniato) and the two biological phases of fruiting bodies formation in San Miniato truffles.

N source affects freeze tolerance in bermudagrass and zoysiagrass

Abstract During cold acclimation, warm-season grasses exhibit growth stall and eventually the onset of rest. Late-season N fertilization is an alternative way for reduction of the dormancy period. The objectives of the present study were (1) to assess the effects of different N sources, and timing on freezing tolerance using controlled environment acclimation and freezing procedures and (2) to determine the relationship of nonstructural carbohydrates and photosynthetic pigments with the freeze tolerance of bermudagrass and zoysiagrass. source treatment exhibited a relative peak at 14 days (2 weeks) before the treatment. In bermudagrass, treatment depressed starch accumulation at 14 and 28 days compared to the control. As expected, in both species a higher concentration of soluble carbohydrates were observed in sprigs tissues. A sharp decline was evident on the treatment in leaves, stems, and roots tissues at 14 days, in correspondence with a lower freeze tolerance, whereas in the treatment an accumulation in total soluble sugars was observed in rhizomes at 28 days. Over the time, chlorophylls showed a slight increase in the treatment, while an opposite trend was detected in the treatment. Overall, N source provided consistent differences in freeze tolerance in both species.

Freeze tolerance of Zoysia matrella (L.) Merrill as affected by late-season nitrogen application, and changes in carbohydrates during cold acclimation

Abstract This study was conducted with the aim of (1) assessing the development of freeze tolerance (LT50) in “Zeon” zoysiagrass under the effect of two different levels (15 and 30 g m−2) of late-season nitrogen applications, and (2) evaluating the dynamics of nonstructural carbohydrates composition during cold acclimation and overwintering. A combined approach with natural acclimation in the field, followed by monthly controlled exposure to sub-freezing temperatures, was employed to evaluate LT50. Fall color of “Zeon” zoysiagrass was improved by nitrogen applications, the latter extending the green period by more than one month. In October, the higher nitrogen treatment caused significantly less cold hardiness (LT50=−10.0°C) compared with the other treatments, but was beneficial to freeze tolerance in March. The controls reached cold hardiness in November, 1 month earlier than the N treatments, in agreement with the color retention data. Controls also showed a more linear freeze tolerance during the experimental period. Significant variations in total soluble sugars occurred in zoysiagrass tissues during the acclimation and de-acclimation process. In particular, in leaves and, partially, in stems, total soluble sugars (TSS) levels were associated with LT50, while sprigs and roots did not show any significant association between LT50 and TSS. Alteration of metabolism was more evident in the 30-g N treatment, in particular as regards the storage sink.

Responses in chemical traits and biomass allocation of Arundo donax L. to deficit resources in the establishment year

A large expansion in renewable energy production is underway with an increasing focus on sustainable second-generation biofuels. Fast growing rhizomatous perennial grasses are leading candidates for lignocellulosic feedstock thanks to their positive energy balance, and low ecological/agro-management demands. Biomass accumulation is favored by the efficient use of available resources. The aim of this study was to identify which accumulation processes were most affected in the establishment year of a giant reed (Arundo donax L.) field crop grown under water and N deficiencies. The relative plasticity of growth of A. donax in response to various levels of resource availability was evaluated. A field scale experiment was carried out, and treatments were arranged as a randomized complete block, strip-plot design with irrigation treatments as the main plot factor and pre-planting N rate as the sub-plot factor. Biometric relationships between variables were assessed to understand how agro-management factors influence the above ground biomass of giant reed, as well as yield over time. Evidence is presented indicating that growth is strongly enhanced by water availability (+97% dry weight biomass). Changes in composition were not significant within or among fixed treatments, rather changes were observed over time. A high content of glucans and xylans were detected from early stage, and as the mobilization of minerals increased, lignin content significantly increased as well (from 12% to 36% w/w). These results suggest that an increase in the growth of A. donax in the establishment year is accomplished by a limited use of the water input

Carbohydrate content, characterization and localization in bermudagrass stolons during establishment

Abstract Turfgrasses are continuously exposed to a wide range of detrimental stresses, such as mowing, traffic, low or high temperatures, salinity, drought, UV, hypoxia etc. Plant responses to stimuli involve nearly every aspect of plant physiology and metabolism. Carbohydrates, primary sucrose and starch, as principal metabolic products of photosynthesis, are stored in bermudagrass (Cynodon spp.) in stolons and rhizomes. Total nonstructural carbohydrates (TNC) levels have been used as indicators of health and physiological status in bermudagrass. TNC levels vary during the year and are weakly affected by N source. Establishment is a critical phase of bermudagrass management. The objectives of this research were to assess and characterize stolon carbohydrate content in nine bermudagrass cultivars during the full establishment phase in relation to establishment rates. Morphological and growth analyses showed distinct properties among the cultivars selected for this study. Significant differences in turf coverage among cultivars on each rating date were present starting from early growth stages. Carbohydrates localization was used to differentiate bermudagrass cultivars. The relationships between different carbohydrates and their role on growth were also explored. Gradients along the stolon from tip to older internodes were evident for starch. Our study provides further insight into bermudagrass physiology, with cultivar differences in carbohydrates production and localization providing valuable selection information for turfgrass breeders and practitioners, especially during the first year. Our data indicate that TNC levels were affected by cultivar and stolon maturity level. TNC content was found to correlate with establishment rate.

Aromatic and proteomic analyses corroborate the distinction between Mediterranean landraces and modern varieties of durum wheat

In this paper volatile organic compounds (VOCs) from durum wheat cultivars and landraces were analyzed using PTR-TOF-MS. The aim was to characterize the VOC’s profile of the wholemeal flour and of the kernel to find out if any VOCs were specific to varieties and sample matrices. The VOC data is accompanied by SDS-PAGE analyses of the storage proteins (gliadins and glutenins). Statistical analyses was carried out both on the signals obtained by MS and on the protein profiles. The difference between the VOC profile of two cultivars or two preparations of the same sample - matrices, in this case kernel vs wholemeal flour - can be very subtle; the high resolution of PTR-TOF-MS - down to levels as low as pptv - made it possible to recognize these differences. The effects of grinding on the VOC profiles were analyzed using SIMPER and Tanglegram statistical methods. Our results show that it is possible describe samples using VOC profiles and protein data.

The positive role of steviol glycosides in stevia (Stevia rebaudiana Bertoni) under drought stress condition

Steviol glycosides (SVglys) are a group of diterpenoids mainly present in the leaves of stevia (Stevia rebaudiana Bertoni). An experiment was conducted to find the functional role of SVglys compounds in stevia affected by drought stress. In this study, a liquid blend of SVglys (200 ppm) was sprayed on stevia plants grown in well-watered (90% field capacity) and drought-stress conditions (45% field capacity) and then the morphological traits and metabolites were evaluated. It was observed that leaf losses caused by drought stress were stopped through external application of SVglys and consequently the harvest index of stevia was increased. Metabolite analysis of stevia leaves showed that the total SVglys content was significantly decreased due to drought stress, but was compensated by external application of SVglys. Among the SVglys, Rebaudioside A responded more to external SVglys. A slight promotion in total antioxidant activity of stevia leaves was observed when external SVglys was applied. The glucose availability in stevia leaves was increased by external application of SVglys but only in well-watered plants. According to our findings, it can be concluded that in stevia, SVglys may have a positive function in drought stress tolerance by exerting a protective role under such conditions.

Carbohydrate Metabolism During Wintering Period in Four Zoysiagrass Genotypes

Abstract A key barrier to widespread use of warm-season grasses in the transition zone between the temperate and subtropical climates is represented by the winter dormancy, a temporary suspension of visible growth of any plant structure including the meristem. In this environment, species with different photosynthetic carbon cycle coexist, leading to asynchrony in growth among warm- and cool-season grasses. The objectives of the present study were (i) to assess the carbohydrate content in four representative zoysiagrasses Zoysia japonica ‘El Toro’, ‘Meyer’, Z. pacifica, and Z. matrella ‘Zeon’ during three successive phases of vegetation phenology, senescence, dormancy, and green-up, and (ii) to characterize the metabolic responses to phenological variations under natural acclimation. Japanese lawn grass genotypes ‘El Toro’ and ‘Meyer’ showed longer dormancy periods than fine-leaved Z. pacifica and ‘Zeon’. In Japanese lawn grass genotypes, the progressive decline of photosynthetic pigments was similar to that observed in the color retention. Over the experimental period, a significantly greater amount of starch reserves was observed in sprigs (horizontal stems) in the Japanese lawn grasses than in the fine-leaved zoysiagrasses. In general, total soluble sugars (TSS) in leaves and sprigs did not show evidence of sugar starvation during the senescence phase. TSS increased significantly during cold acclimation, resulting in a higher metabolic activity at the onset of green-up to support spring regreening in all zoysiagrasses except ‘Meyer’ leaves.

Inter- and intraspecific variability in physiological traits and post-anoxia recovery of photosynthetic efficiency in grasses under oxygen deprivation

Low oxygen conditions occur in grass sites due to high and frequent precipitation, poor soil quality, and over-irrigation followed by slow drainage. Three warm-season and one cool-season grass were analyzed at metabolic level during a time-course experiment performed in a controlled anoxic environment. Prolonged oxygen depletion proved detrimental by leading to premature death to all the species, with the exception of seashore paspalum. Moreover, the anoxia tolerance observed in these grasses has been associated with slow use of carbohydrates, rather than with their relative abundance, which was more important than their antioxidant capacity. Further physiological characterization of eight seashore paspalum genotypes to anoxia was also performed, by examining the variation in photosystem II (PSII) efficiency and gas exchange during post-anoxia recovery. Multivariate analysis highlighted the presence of three main clusters of seashore paspalum genotypes, characterized by different ability to restore the PSII photochemistry during recovery after one day of anoxia. Taken together, our data demonstrate that the analysis of post-anoxia recovery of fluorescence and gas exchange parameters can represent a fast and reliable indicator for selecting species and cultivars more able to acclimate their photosynthetic apparatus.

Nitrate Reductase Modulation in Response to Changes in C/N Balance and Nitrogen Source in Arabidopsis

Environmental cues modulate the balance of carbon (C) and nitrogen (N) which are essential elements for plant metabolism and growth. In Arabidopsis, photochemical efficiency of PSII, phosphorylation status and localization of many enzymes, and the level of total soluble sugars were affected by an unbalanced C/N ratio. Since differences in C/N affect these parameters, here we checked whether different sources of N have different effects when a high C/N ratio is imposed. NO3- and NH4+ were separately provided in C/N medium. We investigated the effects on photochemical efficiency of PSII, the level of total soluble sugars and nitrate reductase activity under stressful C/N conditions compared with control conditions. We found that treated plants accumulated more total soluble sugars when compared with control. Photochemical efficiency of PSII did not show significant differences between the two sources of nitrogen after 24 h. The actual nitrate reductase activity was the result of a combination of activity, activation state and protein level. This activity constantly decreased starting from time zero in control conditions; in contrast, the actual nitrate reductase activity showed a peak at 2 h after treatment with NO3-, and at 30 min with NH4+. This, according to the level of total soluble sugars, can be explained by the existence of a cross-talk between the sugars in excess and low nitrate in the medium that blocks the activity of nitrate reductase in stressful sugar conditions until the plant is adapted to the stress.