Most viruses that infect plants possess single-stranded RNA.Approximately, around 70% of viruses infecting the plants are ssRNA, 20% are ssDNA and rest are either dsRNA or dsDNA. ssRNA genomes serve as mRNAs and virus-encoded proteins are produced immediately after entry of viral RNA to cell cytoplasm. There is no need, as in the case of DNA viruses, to transport genetic material to the nucleus, where viral DNA has to be transcribed and reproduced. Therefore, using viral genomic RNAs as mRNAs make possible to reduce the number of steps from virus entry to replication, which could be targeted by host defenses. All this could be more important for plant viruses because of the differences between viral spread between plant cells and between animal cells.