Caractérisation et distribution du virus de la panachure du poivron en Afrique de l'Ouest

Résumé

Pepper veinal mottle virus (PVMV) was first reported in Ghana and later in Cote d'Ivoire, Nigeria, Ethiopia, Senegal, Togo and Burkina Faso. It is a Potyvirus transmitted in a nonpersistent way by many aphid species, but it is not seed transmitted. In West Africa, its incidence can reach an epidemic scale in pepper, tomato and eggplant fields. PVMV is serologically related to six other Potyviruses. Our study was undertaken to assess distributions and pathogenic PVMV patterns in four West African countries, i.e. Benin, Burkina Faso, Cote d'Ivoire and Mali. An extensive survey was conducted based on symptoms, host plants and agroecological zones. In an analysis of 350 leaf samples from pepper, tomato, eggplant and wild plants, PVMV was detected in 188 samples by DAS-ELISA (Table 1). Two epitope profiles of the virus were distinguished in IDAS-ELISA using five monoclonal antibodies (Mabs) raised against a PVMV isolate from Nigeria (Figure). The first profile included 187 isolates showing the same reaction as the original antigen with the five monoclonal antibodies. Only one isolate (from Burkina Faso) reacted like the negative control with three out of the five monoclonal antibodies, and like the homologous antigen with the two others. Using a wide host range (including two pepper lines, i.e. cv Perennial and cv HD 801, tomato, cv Petomech, and eggplant, cv Florida market), 148 PVMV isolates among the 188 were separated into two pathogroups (Table 2): one including 56 infected pepper (cv Perennial), tomato and eggplant isolates - while the other did not infect any of these hosts. It is concluded that in West Africa PVMV displays high serological homogenity, which should make serological detection rather easy. The two pathogroups among PVMV isolates should be taken into account in breeding programs aimed at developing resistant pepper varieties.