Identification of new Potato virus Y (PVY) molecular determinants for the induction of vein necrosis in tobacco

Abstract

SUMMARY: Two tobacco vein necrosis (TVN) determinants, the residues K400 and E419, have been identified previously in the helper component-protease (HC-Pro) protein sequence of Potato virus Y (PVY). However, since their description, non-necrotic PVY isolates with both K400 and E419 necrotic determinants have been reported in the literature. This suggests the presence in the viral genome of other, as yet uncharacterized, TVN determinant(s). The identification of PVYN pathogenicity determinants was approached through the replacement of genomic regions of the necrotic PVYN-605 infectious clone by corresponding sequences from the non-necrotic PVYO-139 isolate. Series of PVYN/O chimeras and site-directed PVY mutants were constructed to test the involvement of different parts of the PVY genome (from nucleotide 421 to nucleotide 9629) in the induction of TVN symptoms. The analysis of both the genomic characteristics and biological properties of these mutants made it possible to highlight the involvement, in addition to residues K400 and E419, of the residue N339 of the HC-Pro protein and two regions in the cytoplasmic inclusion (CI) protein to nuclear inclusion protein a-protease (NIa-Pro) sequence (nucleotides 5496-5932 and 6233-6444) in the induction of vein necrosis in tobacco infected by PVY isolates. © 2012 THE AUTHORS. MOLECULAR PLANT PATHOLOGY © 2012 BSPP AND BLACKWELL PUBLISHING LTD.