Due to the worldwide predominance of CymMV, molecular variability of CymMV isolates have been extensively studied. In 2002, Ajjikuttira and colleagues compared the CP of 26 Asian isolates [25], and found 89% and 93% identity at the nucleotide and amino acid levels, respectively, with no distinct region of variability in the sequences. In another study, 85 CP and 37 RdRp genes of CymMV isolated from vanilla isolates and other plant sources had a low genetic diversity [26]. Based on phylogenetic studies, CymMV may be categorized into two subgroups based on their nucleotide variations. Although the isolates differ in nucleotide sequences, no clustering in amino acid sequences were seen, suggesting that nucleotide variations are mostly synonymous substitutions. The genetic diversity of CP genes of 108 CymMV isolates from different geographical locations have been compared with 55 CymMV Korea isolates that infect different genera of orchids [27]. The authors noted 75% and 53% CP homology at nucleotide and amino acid levels, respectively, between the two groups of isolates. Similar to those observed by Moles and colleagues (2007), no region of variability was found between the two groups of viruses. Overall, this suggests the absence of a positive correlation between the geographical locations of the CymMV and their sequence identities; the CymMV isolates have low levels of diversity despite being situated at different geographical locations. Further analysis suggested that the C-terminal region of CymMV CP amino acid sequences is more divergent than the N-terminal region. Since the CymMV CP proteins of different isolates show little diversity and are not geographically distinct, it suggests a potential use of the N-terminal region as a transgene target for the generation of CymMV-resistant orchids worldwide.