Viral suppressors: Small RNAs regulators

In eukaryotes, small RNA molecules regulate gene expression by RNA interference in a sequence specific manner. This process fulfills fundamental regulatory roles for developmental activities and defense mechanisms through regulation of micro RNAs and small interfering RNAs respectively. Viruses can overcome this defense by involving various anti-silencing strategies that are being progressively unraveled. Various viral suppressors are known to regulate small RNA world and trigger a series of developmental defects as well as counter defense responses. Here, we review our current understanding of how small RNAs (micro and siRNA) are regulated by structurally diverse viral suppressors from different plant viruses. We focus on the currently known plant virus encoded suppressors and their mode of action in RNA interference. These studies have not only highlighted our basic understanding of host-virus interactions, but also provide key insight of RNA-silencing pathways, which can be exploited in number of ways.