Variation in the coat protein of Strawberry mild yellow edge virus and the complete sequence of aphid transmissible strain D-74

The complete nucleotide sequence of Strawberry mild yellow edge virus isolate D74 was obtained and analysed and found to have an 86% identity to the non-transmissible Agrobacterium infectious MY18 isolate. The coat protein and flanking sequences of twenty three isolates of Strawberry mild yellow edge virus (genus Potexvirus) (SMYEV) were also obtained. Nucleic acid identities ranged from 84.6% to 100%. Phylogenetic analysis of the coat protein showed the isolates fell into three distinct groups I, II and III. Group I contained the majority of isolates including D74, group II contained only 5 isolates, and Group III contained only 4 isolates, including MY18. All isolates from groups II and III were from the American continent. Recombinants between isolates D-74 and MY-18 were made in order to assess infectivity and transmissibility. However, the results were inconclusive since all recombinants but one case resulting in a loss of infectivity.