The genome of viruses is composed of either RNA or DNA molecules. Viruses with multiple RNA segments exchange these segments with other viral species/strains and create variability and ultimately affect the viral pathogenicity.
In plants, some miRNAs can trigger production of secondary siRNAs from their targets. miRNA-induced gene silencing (MIGS) is based on this unique feature to efficiently downregulate gene expression. The simple flanking of a sequence of interest with the target site for miR173 is enough to initiate the generation of secondary siRNAs and, subsequently, silencing of the target gene/s.
In the past, plant scientists mostly relied upon forward genetics; which involved identification of a mutant and subsequent cloning of the mutated gene to identify the gene responsible for the function/trait under investigation. During the last several years, Arabidopsis, rice, tomato, cassava, pigeon pea, chick pea and other plant genomes have been sequenced and large data base of sequence information has been generated. Such genome and EST sequencing projects have generated a wealth of sequence information for important plant species of which the majority is difficult to subject to functional genomics.