Abstract
MicroRNAs (miRNAs) are small, noncoding RNAs that can play important roles in eukaryotes by mRNA degradation, and translation repression. To investigate whether miRNAs regulate gene expressions in the flowering process of woody plants, we analyzed small RNAs expressed at flowering stage of Eucalyptus. First we isolated RNAs from flower buds of Eucalyptus, and then separated small RNAs by polyacrylamide gel electrophoresis. Twenty-two bases of the small RNAs were sequenced by MPSS method, and about 120,000 sequence signitures were determined. Next the sequences that have homology with rRNA, tRNA, snRNA, scRNA were removed from the 120,000 sequences, and then genome sequences including the small RNAs were sereached and about 30,000 sequences were taken. Finaly we identified about 500 miRNA candidates by prediction of secondary structures of the 30,000 sequences. Some miRNA candisates have sequence conservation in Arabidopsis or Populus, but unexpectedly many new miRNA candidates were found in Eucalyptus.
