Molecular interaction between two cassava geminiviruses exhibiting cross-protection

► Reassortment of DNA-A and DNA-B components of African cassava mosaic virus (ACMV) and East African cassava mosaic Cameroon virus (EACMCV) does not form viable recombinants. However, in the presence of both components of either virus, the DNA-A component of the other virus replicated and spread in the absence of its B component. ► Failure of ACMV and EACMCV to form viable recombinants is due to the inability of each DNA-A component to trans-replicate the heterologous B component. ► ACMV DNA-A induces a resistance to ACMV and EACMCV as indicated by absence or late symptom development. ► Resistance enabled plants to recover from severe symptoms caused by EACMCV in N. benthamiana, suggesting that the resistance induced is not specific to ACMV and is consistent with the phenomenon of cross-protection between related viruses.