RNA-directed RNA polymerase plays an essential role in the virus replication. a ribonucleoside 5'-triphosphate + RNA(n) = diphosphate + RNA(n+1) The viral replication sites are located at the host chloroplast membrane. The genome of this virus consists of three linear, positive, single-stranded RNAs encapsidated in separate virions designated RNA-alpha, RNA-beta and RNA-gamma. Three proteins (alpha-A, beta-A and gamma-A) are translated directly from these genomic RNAs and the remaining proteins encoded on RNA-beta (beta-B, beta-C and beta-D) and RNA-gamma (gamma-B) are expressed via three subgenomic messenger RNAs. Belongs to the ssRNA positive-strand viruses RNA-directed RNA polymerase family.