Sostanze perfluorurate (PFAS) nell'ambiente agrario: assorbimento, bioaccumulo, effetti fisiologici nelle piante, e nuovi approcci analitici.

Poly- and perfluoroalkyl substances (PFAS) are a class of synthetic molecules widely used in the industry due to their unique physical and chemical peculiarities. The high thermal and chemical stability, together with both hydrophilic and hydrophobic properties, ensure resistance to degradation and bioaccumulative potential. PFAS are ubiquitous in the environment, and their persistence threatens human health. Hence, there is an urgent demand to monitor PFAS global environmental occurrence and accumulation in living organisms. Moreover, contaminated plant-based food represents an important intake source for animals and humans. PFAS have been demonstrated to accumulate in plants, however, information regarding their potential effects on physiology is restricted to only a few species. We selected willow and maize as model plants to evaluate PFAS uptake and examine their impact on some physiological aspects. In particular, willows are known to accumulate large amounts of such chemicals, therefore representing ideal candidates for phytoremediation purposes. We assessed the stomatal opening and phytohormone content after 8-day exposure to a mixture of 11 PFAS, and we investigated whether water movements among plant tissues were perturbed. We demonstrated that (i) PFAS differentially accumulated in roots, stems, and leaves according to their chemical properties, (ii) PFAS-exposed plants showed a reduced stomatal conductance that does not rely on abscisic acid and salicylic acid regulation, and (iii) PFAS-treated plants were more vulnerable to xylem cavitation events. Maize is one of the most important agricultural crops and consumed cereals, thus estimating PFAS uptake and partitioning among plant tissues and molecular mechanisms of PFAS phytotoxicity is paramount. We conducted an evaluation of physiological effects and a root proteomic investigation in maize plants exposed to a mixture of 11 PFAS for 8 days. We proved that (i) PFAS partitioning in plant tissues was similar to that observed in willows, (ii) plant growth, root morphology, and photosynthetic activity were altered as a result of PFAS exposure in a dose-dependent manner, and (iii) cellular metabolic and biosynthetic processes were the most affected, leading to a dysregulated amino acid and fatty acid content in the roots. PFAS monitoring in food is rapidly increasing aiming to reduce the risk of adverse effects on health, and special attention is given to fruits and vegetables. The practice of grafting is widely used in fruit plants and vegetables to enable resistance to pathogens and abiotic stresses, tolerance to extreme weather conditions, and better product quality. To investigate the impact of grafting on PFAS uptake, we set up a field trial experiment in the PFAS-polluted area of the Veneto Region, growing tomato plants with different rootstock combinations. We demonstrated that (i) PFAS accumulated according to the plant’s vigor, (ii) only short-chain PFAS can migrate to fruits, and (iii) the risk associated with the consumption of contaminated tomatoes is of concern. PFAS routine monitoring relies on targeted LC-MS/MS analyses, which ensure high selectivity and sensitivity. However, sample processing and instrumental analysis are expensive and time-consuming. Raman spectroscopy is a versatile and powerful tool to discriminate chemical species, but only a few studies used this technology to detect perfluorinated compounds. Considering the potentialities of this technique, we predicted the Raman spectra of several perfluoroalkyl carboxylic and sulfonic acids, which were validated by experimental data acquired with a confocal Raman microscope. A clear trend in peak shifting depending on the carbon chain length and good congruence between predicted and real data emerged from this study, suggesting Raman spectroscopy as a promising analytical tool for environmental PFAS screening.