High-throughput SOLEXA sequencing of endogenous small RNAs from Arabidopsis thaliana wild-type

The length of Arabidopsis microRNA genes and their precursors (pri-miRNAs) can very between several hundreds bp to several thousands bp. They may contain introns, precursors may undergo alternative splicing, and often there are more than one polyadenylation site. An intriguing question arise: why to transcribe thousands of base pairs to produce a small RNA molecule of about 21 nt in length? We decided to sequence small RNAs from 35-day-old rosette leaves and to map the obtained reads of 18-26 nt in length to Arabidopsis pri-miRNAs. Our analyses revealed the presence of sRNAs that can derive only from miRNA precursors. An example is the identification of a substantial number of miR319b.2 reads. This sRNA is a product of pri-miR319b processing. Our further experimental analyses show that it carries multiple signatures of a functional microRNA 2 samples examined: wild type