Reciprocal complementation of movement function of potato viruses X and A

During isolation of strains of potato viruses X (PVX) and A (PVA) from indigenously collected potato germplasm, an inseparable association between these viruses was discovered. As a result, all the hosts of PVX, used to free PVX from PVA, also showed infection of PVA along with PVX. Furthermore, Nicandra physaloides, which is a host of PVA but not PVX, also did not free PVA from PVX. These results suggested a reciprocal complementation of movement function of these viruses due to which they together infected various hosts sensitive to PVX or PVA. Relative concentration of PVX, in all the hosts tested, was much higher than that of PVA.