Biological, serological and molecular typing of potato virus Y (PVY) isolates from Tunisia.
In Tunisia, potato virus Y (PVY) currently presents a significant threat to potato production, reducing tuber yield and quality. Three hundred and eighty-five potato samples (six different cultivars) collected in autumn 2007 from nine regions in Tunisia were tested for PVY infection by DAS-ELISA. The virus was detected in all regions surveyed, with an average incidence of 80.26%. Subsequently, a panel of 82 Tunisian PVY isolates (PVY-TN) was subjected to systematic biological, serological and molecular typing using immunocapture reverse-transcription polymerase chain reaction and a series of PVYOC- and PVYN-specific monoclonal antibodies. Combined analyses revealed ~67% of PVYNTNvariants of which 17 were sequenced in the 5'NTR-P1 region to assess the genetic diversity and phylogenetic relationship of PVY-TN against other worldwide PVY isolates. To investigate whether selective constraints could act on viral genomic RNA, synonymous and non-synonymous substitution rates and their ratio were analyzed. Averages of all pairwise comparisons obtained in the 5'NTR-P1 region allowed more synonymous changes, suggesting selective constraint acting in this region. Selective neutrality test was significantly negative, suggesting a rapid expansion of PVY isolates. Pairwise mismatch distribution gave a bimodal pattern and pointed to an eventually early evolution characterizing these sequences. Genetic haplotype network topology provided evidence of the existence of a distinct geographical structure. This is the first report of such genetic analyses conducted on PVY isolates from Tunisia.
Laboratory of Molecular Genetics, Immunology and Biotechnology, Faculty of Sciences of Tunis, Campus University, El Manar, Tunis, Tunisia.
M
M
Tayahi
Laboratory of Molecular Genetics, Immunology and Biotechnology, Faculty of Sciences of Tunis, Campus University, El Manar, Tunis, Tunisia.
C
C
Gharsallah
Laboratory of Horticulture, Potato Program, National Institute of Agronomic Research of Tunisia, Ariana, Tunisia.
N
N
Khamassy
Laboratory of Molecular Genetics, Immunology and Biotechnology, Faculty of Sciences of Tunis, Campus University, El Manar, Tunis, Tunisia.|Faculty of Sciences of Bizerte, Zarzouna, Tunisia.
H
H
Fakhfakh
Laboratory of Molecular Genetics, Immunology and Biotechnology, Faculty of Sciences of Tunis, Campus University, El Manar, Tunis, Tunisia fattouma.djilani@yahoo.fr.|High Institute of Biotechnology of Sidi-Thabet, Technopole, Sidi Thabet, Ariana, Tunisia fattouma.djilani@yahoo.fr.
F
F
Djilani-Khouadja
D001482:Base Composition / Q000235:genetics; D001483:Base Sequence; D004797:Enzyme-Linked Immunosorbent Assay; D014644:Genetic Variation; D005843:Geography; D006239:Haplotypes / Q000235:genetics; D058889:Molecular Typing / Q000379:methods*; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D018515:Plant Leaves / Q000821:virology; D017800:Potyvirus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D014416:Tunisia