The main objective of the present study was to evaluate the effect of the sunhemp (Crotalaria juncea) host species on the protective ability of two mild strains of Passion fruit woodiness virus (PWV), named F-101 and F-144, which had failed to protect passion flowers (Passiflora edulis f. flavicarpa) in previous experiments. The nucleotide sequences of the capsid protein (CP) gene and the 3'-non-translated region (3'-NTR) of these mild strains and the severe strain of PWV-SP were compared to confirm their relationship. The results of two protective tests with sunhemp plants in the greenhouse and one test under field conditions showed that all plants infected with either mild strain were protected against infection and/or symptom expression of the severe strain of PWV-SP. Evaluation of the relative concentration of the mild strains in sun hemp leaves showed an apparent uniformity in virus distribution in the leaf tissues, different than that which was previously reported for these mild strains in passion flower leaves. These results agree with previous studies that showed the effect of the concentration of the protective strains and the host species in the protection process.
Crotalaria juncea; cross protection; potyvirus
