Researchers of the CBGP have shown that the introduction in crops of resistance genes against viruses, selected not only for host-range expansion but also for changes in virus survival. Virus survival, a character unrelated with host-pathogen interaction, can condition host-range expansion. This work has been published in Molecular Biology and Evolution.


Infectious diseases are important threats for the socioeconomic welfare of the humanity, and the most devastating ones are those that infect new host populations, i.e, the emergent diseases. Disease emergence may depend on the pathogens’ ability to expand their host range. The evolution of host range expansion is thought to be limited by across host trade-offs in pathogen fitness: the most efficient pathogens in one host would be the less efficient ones in other hosts. In this paper we analyse the fitness trade-offs in a plant-virus system. To control plant viruses the most efficient strategy is the use of resistant crop varieties, but viruses can expand their host range, overcome this resistance and infect otherwise resistant host genotypes, causing a serious economic and ecologic problem.


Many studies show that plant viruses that expand their ability to infect otherwise resistant host genotypes results in a less efficient within host multiplication of the virus in the non-resistant hosts. Here we show that the capacity of pepper-infecting tobamoviruses to expand their host range in pepper genotypes carrying different resistance alleles, in addition to be traded off against diminished multiplication in the susceptible host, is linked to pathotype-specific changes in survival. We also show that survival depends on virus particle stability, which is altered by pleiotropic effects of the amino acid changes responsible for resistance-breaking, and we dissect the structural bases of altered particle stability. Results show that survival should be considered for understanding the evolution of viruses transmitted through the environment. Results also show that plant resistance, in addition of selecting for increased pathogenicity, also selects for changes in survival, a trait unrelated to the host-pathogen interaction that may condition host range expansion.


Host resistance selects for traits unrelated to resistance-breaking that affect fitness in a plant virus - DOI:10.1093/molbev/msu045