Heterologous replicase driven 3′ end repair of Cucumber mosaic virus satellite RNA

To investigate the extent of the 3′ end repair in a satellite RNA of Cucumber mosaic virus (CMV) strain Q (Qsat) by a heterologous Tomato aspermy virus (TAV), a set of biologically active agrotransformants corresponding to the three genomic RNAs of TAV was developed. Analysis of Nicotiana benthamiana plants agroinfiltrated with TAV and either wild type or each of the six 3′ deletion mutants of Qsat revealed that (i) heterologous replicase failed to generate Qsat multimers, a hallmark feature of homologous replicase dependent replication of Qsat; (ii) manifestation of severe symptom phenotypes and progeny analysis suggested that heterologous replicase was competent to repair Qsat deletion mutants lacking up to 3′13 nucleotides (nt) but not beyond and (iii) comparative in silico analysis indicated that the 3′ secondary structural features of the repaired Qsat progeny from heterologous vs homologous driven replicases are remarkably very similar. The significance of these observations is discussed.