RES2OX - Investigating Specialized Metabolism as an integral factor to improve oxidative stress resilience in native plants exposed to metalloid naturally contaminated soils

Global climate changes (GCC) have altered the climate change frequency, determining much more severe environmental disruptions than occurred in the past. Abiotic stresses, such as drought, heat, salt, or heavy metals and metalloids, like arsenic (As), exacerbate GCC effects. Human activities, industrialization, and modern agricultural practices are mainly responsible for the increase in soil contamination by heavy metals. In addition, natural sources contribute about 1/3 of the total annual release of arsenic to the atmosphere, most of which comes from volcanoes. The presence of As in soils affects the plant cycle giving rise to oxidative stress exerted by reactive oxygen species (ROS), such as hydroxyl radicals, superoxide radicals, and hydrogen peroxide. Flavonoids are a representative group of secondary metabolites with various functions in plants protecting them from abiotic and biotic stresses through antioxidant activity. Although the flavonoid scavenger activity is widely recognized, only recently, the interaction between flavonoid accumulation and tolerance to abiotic stresses, such as oxidative stress, was fully elucidated in the plant model species Arabidopsis thaliana. Recent in vivo studies conducted using metabolome and transcriptome profiling of the model species confirmed the role of flavonoids in the enhancement of oxidative tolerance. However, flavonoid function remains to be determined experimentally in naturally tolerant wild plants living in stressful soils. Soils developed on the volcanic substrate, as a considerable part of the Campanian region and Etna surroundings, are rich in neo-formed amorphous alumino-silicates and organo-mineral compounds and have a high binding capacity for trace metals, such as As. The Brassicaceae family comprises several plant species with agronomic and economic significance including model species (e.g. A. thaliana), as well as various cultivated plant species in the Brassica genus (e.g. cauliflower, broccoli, turnip, etc.). Moreover, significant tolerance to As-rich soils was shown for Brassica rapa subsp. sylvestris, a species widely spread in southern Italy including in volcanic substrates.
However, the role of flavonoids in the oxidative stress tolerance in B. rapa remains to be addressed, although the tolerance mechanisms, as adaptive traits, evolved in this species can become a knowledge milestone for future phytoremediation. Through novel untargeted transcriptome and metabolome approaches, non-model species can identify, with unprecedented precision, all the metabolites and expressed transcripts produced by the plant in response to a stress treatment.
Therefore, in the present project, we aim to investigate the role of flavonoids as ROS scavengers, within the tolerance strategy of wild B. rapa naturally growing in soils affected by arsenic, assessed through geochemical approaches, by performing transcriptome and metabolome profiling analyses.