A New Genotype within Cucumber Mosaic Virus Subgroup I: Molecular Characterization of the Polymerase Encoding RNA 2 and its Capability to Overcome Replicase-mediated Resistance

A number of cucumber mosaic virus subgroup I strains originating from Asia were collected and tested for their ability to overcome replicase!mediated resistance[ Strains were inoculated to replicase!mediated resistant plants transformed with a defective RNA 1 construct from Fny! CMV[ Most of the strains were able to overcome resist! ance to some extent[ The resistance!breaking capability of MB!CMV\ PRC!CMV\ C5!CMV and 29RS!CMV was higher in comparison with the other strains tested\ based on the number of infected transgenic plants[ The resist! ance!breaking capability of MB!CMV and PRC!CMV was mapped to RNA 1 of these strains[ The nucleotide sequences of MB!CMVRNA1 was determined and com! pared with other CMVsubgroup I strains[ Data obtained showed that MB!CMV di}ers from all other strains by more than 6) in nucleotide sequence identity[ This indi! cates a high genetic variability within CMV subgroup I strains from Asia based on RNA 1[