The Effects of Papaya Ringspot Virus Infection on the Nitrogen Metabolism of Carica papaya L.: Part I. Protein and Non-protein Nitrogen Contents in Leaves

Abstract

The effects of papaya ringspot virus (PRSV) infection, on protein and non-protein nitrogen contents in the leaves of the host, Carica papaya L. were examined. The protein and non-protein nitrogen contents were affected by the virus, but the total nitrogen content remained significantly unchanged when compared to those of healthy leaves. The changes in the levels of non-protein and protein were first detected in the mechanically inoculated leaves in three hours of inoculation. About one and a half times increase in non-protein and a corresponding decrease in protein nitrogen contents were detected in the inoculated leaves after three hours of inoculation. After 12 weeks of inoculation, a three fold increase in non-protein and a corresponding decrease in protein nitrogen contents were detected in the systemically infected leaves, when compared to those of healthy leaves. Similar effects of PRSV infection were observed in naturally infected field plants.