The network of plants volatile organic compounds

Abstract Plants emission of Volatile Organic Compounds (VOCs) is involved in a wide class of ecological functions, as VOCs play a crucial role in plants interactions with biotic and abiotic factors. Accordingly, they vary widely across species and underpin differences in ecological strategy. In this paper, VOCs spontaneously emitted by 109 plant species (belonging to 56 different families) have been qualitatively and quantitatively analysed in order to provide an alternative classification of plants species. In particular, by using bipartite networks methodology from Complex Network Theory, and through the application of community detection algorithms, we show that is possible to classify species according to chemical classes such as terpenes and sulfur compounds. Such complex network analysis allows to uncover hidden plants relationships related to their evolutionary and adaptation to the environment story

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 VOC's 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

Comparative analysis of Volatile Compounds (potential aromatic ability) in the fruit of 15 olive Italian cultivars

Virgin olive oils (VOOs) are characterized by peculiar flavors appreciated by the consumers all over the world. Their organoleptic characteristics depend on the aromatic properties of the fruits of the different cultivars, which will originate the final products. VOCs spectra of fifteen certified Italian olive cultivars of the University of Florence Germplasm collection, chosen as their different geographical origin, diffusion, and product purpose, were acquired using a Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS). The VOCs analyses highlighted a great variability among the fifteen cultivars, mostly due to compounds (C6 and C5) deriving from polyunsaturated fatty acids through the LOX pathway. The early identification in the olive fruit of these compounds which are considered among the major contributors to the positive VOOs attributes, would be useful to produce high quality olive oils, and get useful information to individuate the best parents for the genetic improvement.

Kinetics of volatile organic compounds (VOCs) released by roasted Coffee during the first ten days after processing

The quality of coffee is linked to the aroma created by the chemical reactions that occur during the roasting process. While it is generally thought that roasted coffee is a stable product with a relatively long shelf-life, little information is available on the evolution (kinetic) of the volatile organic compounds (VOCs) in the days immediately following the process. The aim of this study is to determine the evolution of VOCs released by coffee beans, on samples of Coffea arabica (three different origins) and Coffea canephora (1 single origin), by using a Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) 24 hours after roasting, and for the next 9 days. Results confirmed the differences already highlighted in previous studies between the VOCs spectra of the two species. There were also significant differences in the intensity of emissions for the different origins of Coffea arabica, with the highest VOCs amount over time always detected in the Honduras Arabica samples. The involved detected protonated ions were grouped into three classes: compounds (ppbv) present with decreasing quantity ; weakly increasing; almost constant trend; or always increasing. A complex dynamic emerged for the different protonated ions over time, which not only affects the mass spectra of the different species but also influences the configuration of the mass spectra of the different geographical zones of production

Monitoring in real time the changes in VOCS emission in sunflower and extra virgin olive oil upon heating by PTR-TOF-MS

In this work the emission of volatile organic compounds (VOCs) upon the heating process of an extra virgin olive oil (EVOO) and a high oleic sunflower oil (SFO) was evaluated in real time by spectrometry. Two tests were carried out, in the first VOCs emitted from both kinds of oil were measured at room temperatures (not heated, NH) and at 180°C; in the second test, VOCs emission for selected masses were monitored under increasing temperatures over time: at room temperature not heated oils (NH), 60, 90, 120, 150, and 180°C, respectively. The spectra were acquired using a Proton Transfer Reaction Time of Flight Mass Spectrometer (PTR-ToF-MS). The total VOCs emission increased at 180°C, determined both by the rise of the amount of compounds present in the NH samples and by the formation of new masses generated by oxidative chemical reaction from triglycerides and fatty acids. From the set of results it is evident that a good control of the temperatures can be useful in reducing the quantities of masses potentially harmful to health in human food

Airborne signals synchronize the defenses of neighboring plants in response to touch

Plants activate defense-related pathways in response to subtle abiotic or biotic disturbances, changing their vola-tile profile rapidly. How such perturbations reach and potentially affect neighboring plants is less understood. Weevaluated whether brief and light touching had a cascade effect on the profile of volatiles and gene expression of thefocal plant and a neighboring untouched plant. Within minutes after contact,Zea maysshowed an up-regulation ofcertain defense genes and increased the emission of specific volatiles that primed neighboring plants, making themless attractive for aphids. Exposure to volatiles from touched plants activated many of the same defense-relatedgenes in non-touched neighboring plants, demonstrating a transcriptional mirroring effect for expression of genesup-regulated by brief contact. Perception of so-far-overlooked touch-induced volatile organic compounds was ofecological significance as these volatiles are directly involved in plant–plant communication as an effective trigger forrapid defense synchronization among nearby plants. Our findings shed new light on mechanisms of plant responsesto mechanical contact at the molecular level and on the ecological role of induced volatiles as airborne signals inplant–plant interactions

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