Chapter 11 - Evolution and diversity of plant RNA viruses

Abstract

The RNA viruses rapidly adopt the evolutionary changes due to their unique evolutionary capacities. RNA viruses cover a major fraction of the global virome. The major evolutionary forces that lead to the evolution of viral genome include mutation, recombination and genetic drift selection etc. In an evolving population, mutation is considered as a major source of genotypic diversity. The accurate measurement of rate of mutation is a crucial parameter in the evolution of viruses. Natural selection applies on phenotypic diversity of mutant genomes and forces population towards increased fitness. RNA viruses contain vast genetic and phenotypic diversity and can infect a wide range of hosts. The phylogenomic analysis reveals five major branches of RNA viruses:two of which comprise positive-sense (+) RNA viruses, one is a mix (+) RNA and double-stranded (ds) RNA viruses, and two include dsRNA and negative sense (−) RNA viruses, respectively. This tree topology indicates the evolution of dsRNA viruses from (+) RNA viruses and of (−) RNA viruses from dsRNA viruses. Advances in the fields of bioinformatics, RNA sequencing, phylogenetics and population genetics provide new ways for detailed view of evolution of RNA viruses.