Ricerc@Sapienza

Differently from animals, most of the plant organs are generated during post-embryonic development. This depends on meristems, regions located at the distal sides of the plants. In the meristems a set of self-renewal stem cells divides asymmetrically providing new cells to the growing organs. During embryogenesis, the acquisition of stem cell identity by two different sets of cells located at the basal and apical pole of the embryo, guarantees the generation of the primary meristems: the shoot apical meristem (SAM) and the root apical meristem (RAM).

Recognition of endogenous molecules acting as "damage-associated molecular patterns" (DAMPs) is a key feature of immunity in both animals and plants. Oligogalacturonides (OGs), i.e. fragments derived from the hydrolysis of homogalacturonan, a major component of pectin are a well-known class of DAMPs that activate immunity and protect plants against several microbes. However, hyper-accumulation of OGs severely affects growth, eventually leading to cell death and clearly pointing to OGs as players in the growth-defence trade-off.

The plant cell wall is the barrier that pathogens must overcome to cause a disease and to this purpose they secrete degrading enzymes of the various cell wall components. Due to the complexity of these components, several types of oligosaccharide fragments may be released during pathogenesis and some of these can act as Damage-Associated Molecular Pattern (DAMPs). Well-known DAMPs are the oligogalacturonides (OGs) released upon degradation of homogalacturonan and the products of the cellulose breakdown, i.e. the cellodextrins (CDs).

The role of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) and of the auxin-interacting phytohormone ethylene on xylogenesis is still little known, even if a xylogenic promotion by auxins has been reported. In particular, auxin/ethylene-target tissue(s), modality of the de novo xylary process, and the kind of ectopic elements formed (metaxylem vs. protoxylem) are currently unknown. It is instead widely known that auxins positively affect adventitious root (AR) formation, e.g. in the model plant Arabidopsis thaliana and in in vitro cultured systems of numerous species.

Over the last years, various acellular assays have been used for the evaluation of the oxidative potential (OP) of particular matter (PM) to predict PM capacity to generate reactive oxygen (ROS) and nitrogen (RNS) species in biological systems. However, relationships among OP and PM toxicological effects on living organisms are still largely unknown. This study aims to assess the effects of atmospheric PM-selected components (brake dust - BD, pellet ash - PA, road dust - RD, certified urban dust NIST1648a - NIST, soil dust - S, coke dust - C and Saharan dust - SD) on the model plant A.

Over the last few decades, oxidative stress has been identified as one of the main mechanisms by which particulate matter (PM) exerts its adverse effects on living organisms (Li et al, 2015). During the last years, different acellular assays, such as dithiothreitol (DTT), ascorbic acid (AA) and 2′,7′-dichlorofluorescin (DCFH) assay, have been used for the evaluation of the oxidative potential (OP) of particular matter (PM) to predict PM capacity to generate reactive oxygen (ROS) and nitrogen (RNS) species in biological organisms (Kelly and Fussell, 2012).

Lo stress ossidativo è considerato uno dei principali meccanismi con cui il particolato atmosferico (PM) esercita i suoi effetti negativi sugli organismi viventi (Li et al., 2015). Negli ultimi anni, diversi test acellulari sono stati sviluppati ed utilizzati per valutare il potenziale ossidativo (OP) del PM emesso da diverse sorgenti. Tuttavia, le relazioni tra OP e la capacità del PM di generare specie reattive dell’ossigeno (ROS) e dell’azoto (RNS) in organismi biologici sono ancora in gran parte sconosciute.