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.

We present a statistically derived phytogeographic regionalization based on the spatial distribution of native woody flora, investigating environmental correlates and assessing congruence between the spatial patterns of species, genera, and families. A sector of central peninsular Italy (Lazio and Abruzzo regions) was selected as a case study. A rich georeferenced floristic database was compiled, including information from different sources.

To improve the phytogeographic characterization of peninsular Italy, we analysed and compared the spatial distribution of woody flora at both the species and genus level along an approximate 160 km west–east transect within the central peninsula. Sampling sites were selected using a subjective stratified sampling design. A total of 1710 occurrence records, 138 species, and 74 genera from 153 floristic relevés was used. The congruence in species and genera patterns, supported by Mantel and Procrustes tests, confirmed the validity of the higher‐taxon approach to analyse woody flora patterns.