Ricerc@Sapienza

The root of the plant Arabidopsis thaliana is a dynamic structure in which cells continuously divide and differentiate to sustain its postembryonic undetermined growth. Cells at different developmental stages are organized in distinguished zones whose position and activities are maintained constant during root growth. In this review, we will discuss the latest discoveries on the regulatory networks involved in root zonation and, in particular, in the mechanisms involved in maintaining the position of the transition zone, a root developmental boundary.

Developmental and environmental signaling networks often converge during plant growth in response to changing conditions. Stress-induced hormones, such as jasmonates (JAs), can influence growth by crosstalk with other signals like brassinosteroids (BRs) and ethylene (ET). Nevertheless, it is unclear how avoidance of an abiotic stress triggers local changes in development as a response.

The research was focussed on the effects of cadmium (Cd) and arsenic (As), alone or combined, on Arabidopsis
post-embryonic roots, with attention to quiescent centre formation and development in relation to auxin
homeostasis. To the aim, morphological and histochemical analyses were carried out on seedlings, exposed or
not to Cd and/or As, of wild type, and transgenic lines useful for monitoring quiescent centre identity, auxin
localization and cellular influx and efflux. Moreover, auxin levels and expression of the YUC6 auxin biosynthetic

Hypocotyl elongation is influenced by light and hormones, but the molecular mechanisms underlying
this process are not yet fully elucidated. We had previously suggested that the Arabidopsis DOF
transcription factor DAG1 may be a negative component of the mechanism of light-mediated inhibition
of hypocotyl elongation, as light-grown dag1 knock-out mutant seedlings show significant shorter
hypocotyls than the wild type. By using high-throughput RNA-seq, we compared the transcriptome

Cadmium (Cd) and arsenic (As), non essential, but toxic, elements for animals and plants are frequently present in paddy fields. Oryza sativa L., a staple food for at least the half of world population, easily absorbs As and Cd by the root, and in this organ the pollutants evoke consistent damages, reducing/modifying the root system. Auxins are key hormones in regulating all developmental processes, including root organogenesis. Moreover, plants respond to environmental stresses, such as those caused by Cd and As, by changing levels and distribution of endogenous phytohormones.

Cadmium (Cd) and Arsenic (As) pollution has become a serious factor limiting the growth and productivity of Oryza sativa L. and a risk for human health. Roots are the first organs affected by these pollutants, showing growth inhibition and altered cellular differentiation (Fattorini et al., 2017 doi: 10.1016/j.envexpbot.2017.10.005). Cd and As alter root architecture negatively interacting with hormone biosynthesis and