Characterization of miRNA families in Zea mays L. and Arabidopsis thaliana

PhD thesis of Erica Mica (BIO/11) CHARACTERIZATION OF miRNA FAMILIES IN Zea mays L. AND Arabidopsis thaliana. In this manuscript are collected the results of my analyses about the characterization of miRNAs from Z. mays (maize), one of the most important crops in the world. To further analyze some aspects of the miRNAs characterized in maize, it was considered the model plant A. thaliana (Arabidopsis) that allows deeper molecular investigation. The manuscript is divided into three sections: - the first one is a general introduction, in the form of a review, on the small RNA world, with particular interest on miRNA. - the second one is reported as it was published on Journal of Experimental Biology, in 2006 (Mica et al., 2006). This work was carried out on maize miRNAs that at the beginning of my work were still unknown in this plant. It deals with characterization of five miRNA families in three different maize genotypes. In particular it was investigated MIR genes expression pattern, their phylogenetic relationship with other crops MIR genes and putative function of their mature products, with the long-term goal of unrevealing a possible involvement of miRNAs in heterosis; - the third one reports the analyses of miR169 on Arabidopsis; in particular in situ hybridization technique was used to define a precise expression pattern, and transgenic plants overexpressing miR169 were grown in order to define the role of this miRNA in plants.