[Coexistence and competition of two satellite RNAs of Cucumber mosaic virus in systemic hosts]

Abstract

Two Cucumber mosaic virus (CMV) satellite RNAs, namely Yns and Yi and of 385nt and 369nt respectively, were introduced to systemic host plants with a satellite RNA-free isolate of CMV (CNa), after in vitro transcription of satellite RNAs from cDNA clones and by co-inoculation with CMV genomic RNAs. The competition and coexistence of the two satellite RNAs were studied by RT-PCR detection, double-stranded RNA analysis and sequencing comparison. The results showed that, in the inoculated leaves of Nicotiana glutinosa, both satellite RNA presented together after inoculated 5 days after pseudo-recombination. In the systemic leaves of N. glutinosa, both satellite RNAs were detected at 5 days and 10 days post first inoculation, however, only the 369nt satellite (Yi) was recovered at 15 days post first inoculation and second inoculation transferred from the pseudo-recombination plants. Comparison of full sequences of the satellite RNAs obtained by RT-PCR from pseudo-recombinant virus showed that no mutation and mutual exchange of the satellite genome has been found. The results indicate that both 369nt satellite RNA and 385nt satellite RNA can be introduced to CMV-CNa with in vitro transcription products and both replicated to a high level depending on the helper virus. But after transferring to new systemic plants, only one satellite of 369nt can be kept as co-infection for long with the helper CMV. Co-existence and competition are found between different satellite RNAs in the same plant.