Evidence of recombinant strains of Potato virus Y (PVY) in Argentina

COLAVITA MONICA LILIANA; MARCOS LANCIA; FEINGOLD SERGIO ENRIQUE; MASSA GABRIELA ALEJANDRA

Arrail D´Ajuda

Conferencia; 11th Solanacea Conference (SOL2014).; 2014

Potato Virus Y (PVY) is one of the most common disease agents of potato production worldwide. Severe infections can cause losses from 40 to 70 %. Historically PVY isolates have been divided into three groups of strains PVYO, PVYN and PVYC, based on their pathology in Nicotiana tabacum cv. Samsun, Solanum tuberosum Group Tuberosum and Physalis floridana. Two main recombinant types were reported within the necrotic PVYN group: PVYN with necrotic symptoms in tubers (named PVYNTN) and PVYN Wilga (named PVYNW). PVYNTN, is capable of inducing tuber necrosis, and this symptom is often referred to as potato tuber necrotic ringspot disease (PTNRD).  In this work, forty-six isolates of PVY selected from tubers with PNTRD symptoms and from plants infected only with PVY from fields of different regions of Argentina, were biologically and serologically characterized in order to identify the occurrence of recombinant PVY strains. Out of the 46 PVY isolates studied, 41 (89.6%) showed necrosis in tobacco as PVYN, 5 induced mosaic symptomstypical to PVYC or PVYO strains and 33 isolates produced PTNRD symptoms in cv. Calén INTA. Analyseswith monoclonal antibodies identified three strains PVYN, PVYO and PVYC, 32 isolates with concordance in symptoms and serology data and 14 isolates with some inconsistence between both determinations. Sequences of previously recombined hot spot regions of the genome were further investigated in five selected isolates (ST11, RCA5a, RCA6, RCA14b and SSF6) with conflicting behavior and compared to  PVYN (N605, X97895) and PVYO (O- 139, U09509) reference genomes.  Isolates with one, two and three recombination points were identified among these and also in typical PVYN and PVYO strains (SSF18 and RCA5b) included in the study. This result confirms the occurrence of recombined PVY in Argentina for the first time, and extends the discussion on the appropriate classification of PVY viruses and the role of recombination as a mechanism of viral evolution.