Brona McVittie reports

Congratulations to Epigenome member, David Baulcombe, Professor of Botany (Cambridge University, UK) for winning the prestigious Albert Lasker Award for Basic Medical Research. David won the prize jointly with Victor Ambros (University of Massachusetts Medical School, USA) and Gary Ruvkun (Massachusetts General Hospital, USA) for their discovery of microRNAs.

David and his research team have been exploring the relationships between viruses and their hosts. They’re interested in how plants acquire immunity to infectious agents and indeed how our leafy friends can recognise viruses at the molecular level. Such knowledge is key to breeding and engineering disease resistant plants and to understanding how immunity evolves.

The complex molecular interplay between host and virus includes RNA-based processes collectively known as RNA silencing. RNA has many functions inside cells. Before DNA becomes protein, the code must be transcribed through RNA. In addition to this role, short RNA molecules (not long enough to specify a protein product) play a helping hand in the direction of immune proteins.

For decades scientists have been aware that plants infected with a virus are resistant to infection by the same or related viruses, but not unrelated viruses. We now know that this immunity results from the presence of short silencing RNAs that are derived from the viral genome. These RNAs guide a protein called Argonaute to destroy the RNA of related viruses that might infect the plant. Coupled with that, there is an impact on the transcription of DNA at a chromatin level.

More generally, silencing has a role beyond virus resistance: it protects the genome by silencing transposons (mobile DNA elements that can hop around the genome). This maintains the integrity of chromosome structure and function and keeps gene expression right during growth, development and in response to external stimuli.

David is also keen to explore epigenetic effects in evolution, the role that RNA silencing has on natural variation within and between species.