This study aimed to evaluate how seasonal variations in environmental conditions and atmospheric NO 2 impact C and N cycle in an urban environment by determining their elemental concentration and isotopic composition (δ 13 C, δ 15 N) at spatial scale (urban and peri-urban sites) and species level (evergreen plants). Leaves and soil across the medium-sized city of Pisa were collected over 1 year including COVID-19 lockdown, taking advantage of the unprecedented containment measures causing a substantial NO 2 drop. The enrichment in heavier isotopes of organic matter in urban soil was most likely due to the long-term contribution of both δ 15 N-enriched depositions and greater C and N cycling rates in comparison with peri-urban soil. Leaf δ 15 N represented a valuable proxy of the urbanization degree depending on microclimate and N inputs from atmospheric NO 2 . Leaf δ 13 C showed a seasonal trend linked to plant functional types, with significant differences between sites and species. Differently from Nerium oleander and Pittosporum tobira , Quercus ilex showed a positive correlation between δ 13 C and NO 2 , highlighting the positive effect of N deposition on its intrinsic water-use efficiency. Moreover, the lockdown-induced NO 2 reduction was reflected in a decreasing trend of leaf N concentration and change in intrinsic water-use efficiency depending on the plant species and urbanization degree. Q. ilex showed the best adaptability to the more NO 2 -polluted site, being able to uptake and immobilize high amounts of 15 N-enriched atmospheric depositions into its leaves without toxic effects. Overall, these results must be considered in urban greening programs to improve air quality in NO 2 -polluted areas.
Salinity stress impairs growth and physiological performance in tomato, which is one of the most economically important vegetables and is widely cultivated in arid and semi-arid areas of the world. Plant landraces, which are heterogeneous, local adaptations of domesticated species, offer a unique opportunity to valorize available germplasm, underpinning the productivity, resilience, and adaptive capacity of staple crops in vulnerable environments. Here, we investigated the response of fully mature tomato plants from a commercial variety, an ancestral wild relative, and a landrace under short-term salinity exposure, as well as their ability to recover upon cessation of stress. The heterogeneous panel evaluated in this study revealed different adaptative strategies to cope the stress. Our data highlighted the ability of the tomato clade to handle low and intermediate salinity stress for short-term exposure time, as well as its capacity to recover after the cessation of stress, although inter- and intraspecific variations in morphological and physiological responses to salinity were observed. Overall, the landrace and the wild type performed similarly to control conditions under low salinity, demonstrating an improved ability to maintain ionic balance. In contrast, the commercial genotype showed susceptibility and severe symptoms even under low salinity, with pronounced reductions in K+/Na+ ratio, PSII photochemical efficiency, and photosynthetic pigments. This research confirmed that improved salt tolerant genotypes can lead to substantial, positive impacts on horticultural production. While the salt tolerance mechanism of domesticated tomato was efficient under mild stress conditions, it failed at higher salinity levels.
Investigation of cultivated plant physiology grown under low energy input plays an important role to indicate their fitness to the new environmental conditions. The durum-wheat cultivars Creso and Dylan were tested to evaluate the growth, production, and proteomic and transcriptomic profiles of the crop under different synthetic and organic nitrogen fertilization regimes. In this work, a two-dimensional gel electrophoresis (2-DE) approach combined with liquid chromatography-mass spectrometry (LC-MS) was used to investigate the protein changes induced by the use of different nitrogen sources (hydrolysate of proteins 1 and 2, rhizovit, synthesis, leather) on wheat plants. Proteomic studies were integrated with qPCR analysis of genes related to glutamine synthetase/glutamine-2-oxoglutarate aminotransferase (GS-GOGAT) and tricarboxylic acid (TCA) metabolic pathways because most relevant for nitrogen-dependent plants growth. The proteomic analysis lead to the isolation of 23 spots that were able to distinguish the analyzed samples. These spots yielded the identification of 60 proteins involved in photosynthesis, glycolysis, and nitrogen metabolism. As an example, the quinone oxidoreductase-like protein and probable glutathione S-transferase GSTU proteins were identified in two spots that represents the most statistically significant ones in Dylan samples. Transcript analysis indicated that related genes exhibited different expression trends; the heat map also revealed the different behaviors of the hydrolysates of the proteins 1 and 2 nitrogen sources. The effects of nitrogenous fertilizers at the proteomic and agronomic levels revealed that plants fertilized with synthesis or rhizovit gave the best results concerning yield, whereas rhizovit and protein hydrolysates were most effective for proteins content in the grain (% of dry weight). Therefore, all parameters measured in this study indicated that different kinds of nitrogen fertilization used have a relevant impact on plant growth and production.
