Tracking the Population Dynamics of Plant Virus Escape Mutants

Abstract

One of the most challenging problems in agronomy is to obtain plants that are resistant to the infection of pathogens. Not only this, but also that resistance must be as durable as possible. Unfortunately, most, if not all, strategies to generate such resistant plants have been overcome by the tremendous evolutionary potential of viral pathogens. In recent years, a new strategy based on the transgenic expression of artificial micro-RNAs (amiRs), designed to target viral genomes and induce their degradation, has been developed. This resistance has proven to be highly effective and sequence-specific against several plant viruses infecting Arabidopsis thaliana [7]. However, before these transgenic plants can be deployed in the field, it was important to evaluate the likelihood of the emergence of resistance-breaking mutants [2, 5]. Two issues were of particular interest: (1) whether such mutants can arise in non-transgenic plants that may act as reservoirs for the viral populations and (2) whether a suboptimal expression level of the transgene, resulting in sub-inhibitory concentrations of the amiR, would favor the emergence of escape mutants.