Background Cucumber mosaic virus (CMV) causes serious diseases in agricultural crops worldwide, predominantly in vegetable and ornamental plants. A critical interaction has been reported between the plant Ferredoxin I (Fd I) protein with the coat protein (CP) of the M strain of CMV (M-CMV) but not by the CP of the Q strain of CMV (Q-CMV). To ascertain the most likely symptom development model based on CMV CP interacting with the plant Fd I protein, further in silico investigation was performed on the CPs of the two strains (severe chlorosis symptoms (M-CMV) and mild symptoms (Q-CMV)). The biological assembly of the CMV CP is composed of hexameric and pentameric units.
Result The results showed that there were significantly different interactions between pentameric and hexameric form of M and Q-CMV CPs with Fd I. Pentameric structural forms of M-CMV CP interact strongly with Fd I compared to pentameric structures of Q-CMV CP, while there were not significantly different in affinity for hexameric structures between M and Q-CMV CPs.
Conclusion Accordingly, it can be deduced that probably pentameric structures of M-CMV (higher pathogenicity) CP block activation of plant Fd I protein. Therefore, it can be concluded that trapping Fd I in the complex of pentameric structures can lead to inhibition of the activity of plant Fd I in the photosynthetic electron transport chain leading the severe symptom development seen in M-CMV infected plants but not in Q-CMV infected plants. It seems likely that any factor that inhibits the interaction of CMV CPs with plant Fd I can prevent this symptom development.