Semirna: searching for plant miRNAs using target sequences

Many plant genomes are already known, and new ones are being sequenced every year. The next step for researchers is to identify all of the functional elements in these genomes, including the important class of functional elements known as microRNAs (miRNAs), which are involved in posttranscriptional regulatory pathways. However, computational tools for predicting new plant miRNAs are limited, and there is a particular need for tools that can be used easily by laboratory researchers. We present semirna, a new tool for predicting miRNAs in plant genomes, available as a Web server. This tool takes a putative target sequence such as a messenger RNA (mRNA) as input, and allows users to search for miRNAs that target this sequence. It can also be used to determine whether small RNA sequences from massive sequencing analysis represent true miRNAs and to search for miRNAs in new genomes using homology. Semirna has shown a high level of accuracy using various test sets, and gives users the ability to search for miRNAs with several different adjustable parameters. Semirna, a user-friendly and intuitive Web server for predicting miRNA sequences, can be reached at http://www.bioinfocabd.upo.es/semirna/ . It is useful for researchers searching for miRNAs involved in particular pathways, as well as those searching for miRNAs in newly sequenced genomes.