Effect of Papaya Ring Spot Virus (PRSV) infection on nitrogen, protein and carbohydrate contents in papaya

Abstract

The present investigation was undertaken to assess the impact of PRSV infection on assimilation of nitrogen, protein and carbohydrates in the vegetative parts of the host Carica papaya L. The nitrogen and protein contents were higher in infected tissue compared to healthy counterparts. The nitrogen and protein content was maximum in leaves and minimum in roots (for both healthy and diseased samples). Initially, there was a very slight increase in nitrogen and protein content values due to infection, but a progressive rise was noted in older tissues. However, the carbohydrate content including reducing sugars, non-reducing sugars and starch, was found to be lower in infected tissues compared to their healthy counterparts, but the carbohydrate content value of old tissues was higher than the younger ones (for both healthy and diseased samples). The data was statistically significant and results were critically discussed. It is concluded that PRSV infection stimulates biosynthetic pathways for increased synthesis of amino acids for viral requirements resulting in rise in nitrogen and protein content causing biosynthesis of amino acid due to breakdown of assimilated carbohydrates, which are reduced due to infection. Reduced productivity in leaves and poor assimilation of carbohydrates results in heavy yield loss.