MicroRNA EXPRESSION IN MAIZE AND WHEAT

BERDAT CINTIA; EZEQUIEL MARGARIT; MARTÍN I. REGGIARDO; RUBEN H. VALLEJOS

Rosario

Congreso; 42 th Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2006

SAIB - Sociedad Argentina de investigación en Bioquímica y Biología Molecular

MicroRNAs are tiny RNAs of 20-24 nucleotides which are processed from long RNA precursors transcribed from the plant genome. These miRNAs regulate by traductional repression or mRNA cleavage the expression of several genes, mostly transcription factors. 767 miRNAs were identified in plants and 24 families of them were shown to be conserved among Arabidopsis thaliana, rice and other species. Here we studied 17 conserved miRNAs by Northern blotting of low molecular weight RNAs isolated from 6 different tissues from maize and wheat. The expression of these miRNAs differed widely among these tissues. Interestingly the expression of miR167 and miR171 was higher in maize endosperm of 14-27 days after pollination (DAP) than in the embryos while the expression of miR159 and miR396d in maize endosperm was highest at 7 DAP and decreased sharply afterwards. In contrast, the expression of several miRs (miR156, miR159, miR167 and miR171) was higher in immature wheat embryos than in endosperm. The putative targets in these cereals of miRNAs of interest were predicted with the miRU software and their expression in the same tissues confirmed by RT PCR. Experiments of 5¢ RACE were done to determine which is the target that is really being modulated by the miRNAs.