Virus Research 141 (2009) 184–189 Contents lists available at ScienceDirect Virus Research journal homepage: www.elsevier.com/locate/virusres Seed, soil and vegetative transmission contribute to the spread of pecluviruses in Western Africa and the Indian sub-continent B. Dieryck a , G. Otto a , D. Doucet a , A. Legrève a , P. Delfosse b,1 , C. Bragard a,∗ a Unité de phytopathologie, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium b Virology Unit, ICRISAT Sahelian Center, Sadoré, Niger article info Article history: Available online 17 January 2009 Keywords: Pecluvirus Peanut clump Epidemiology Seed transmission Soil transmission Polymyxa graminis abstract Peanut clump and sugarcane red leaf mottle diseases are caused by viruses of the genus Pecluvirus. Indian peanut clump virus occurs in the Indian sub-continent and Peanut clump virus in West Africa. A feature of these viruses is that they are both seed and soil transmitted. Both modes of transmission contribute to long-term persistence and field spread. Data on seed transmission in pearl millet, virus movement within the plant and virus diversity based on RNA-1 partial sequences are presented. This study emphasizes that pecluviruses are also viruses of cereals infecting sorghum and pearl millet, and highlights a correlation between the countries cultivating these two crops and the virus distribution. Ways of controlling pecluviruses and their vector, Polymyxa graminis, taking into account the virus dissemination routes, are proposed. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Peanut clump and sugarcane red leaf mottle are endemic dis- eases that occur in West Africa (Baudin and Chatenet, 1988; Dollet et al., 1987; Rott, 1996) and the Indian sub-continent (Rao et al., 2002; Reddy et al., 1983; Delfosse et al., 1995a). The causal agent in Africa is Peanut clump virus (Thouvenel et al., 1976) and in the Indian sub-continent it is Indian peanut clump virus (Reddy et al., 1983) which is a closely related species and also ascribed to the genus Pecluvirus. Both clump and red leaf mottle diseases have been known since the 1920s (Sundararaman, 1927; Trochain, 1931) and the viruses responsible have been increasingly well characterized during the last 30 years (Herzog et al., 1994, 1995; Miller et al., 1996; Naidu et al., 2003). Peanut clump disease is often confused with groundnut rosette, caused by Groundnut rosette assistor virus and Groundnut rosette virus, because of the diverse symptoms expressed. These range from clumping with dark green leaves to chlorotic leaf spots, line patterns, vein yellowing, mottle or light mosaic, with or without decreased plant growth (Manohar et al., 1995; Nolt et al., 1988; Rott, 1996). The viruses are often present in asymptomatic plants. Both monoclonal and polyclonal antibodies have been devel- oped to detect and identify the viral agents using microprecipi- tation, ISEM or phosphatase- and penicillinase-based DAS-ELISA ∗ Corresponding author. Tel.: +32 10474023; fax: +32 10478697. E-mail address: claude.bragard@uclouvain.be (C. Bragard). 1 Present address: Centre de Recherche Public-Gabriel Lippmann, L-4422 Belvaux, Luxembourg. (Huguenot et al., 1989; Reddy et al., 1998). In this way, different serotypes or serogroups have been distinguished in Africa and India (Manohar et al., 1995). This has rendered the serological detection and identification of the disease cumbersome and inefficient. The host range of pecluviruses is much wider than groundnut and sugarcane. Moreover, the role of cereals in seed transmission is an unique feature of protist-transmitted soil-borne plant viruses, as is their importance in the build-up of inoculum in the soil (Delfosse et al., 1999; Dollet et al., 1976; Doucet et al., 1999; Legrève et al., 2000, 2005). Clump disease is unlikely to be a matter of serious concern to farmer but for its long-term persistence through the soil-borne Polymyxa graminis vector and the lack of host plant resistance of groundnut (Gibbons, 1987) other than that derived from a trans- genic approach (Dollet et al., 1987; Sharma and Vanamala, 2000). Reports and surveys have previously emphasized the economic importance of the disease (Dollet et al., 1987) though it often remains localized (Delfosse et al., 1995a,b; Manohar et al., 1995; Ndiaye and Dollet, 1995; Rao et al., 2002; Subrahmanyam et al., 1987, 1992). In this study, the role of both seed and soil transmission in the development of epidemic-conducive conditions is analyzed, based on survey data and additional knowledge on virus diversity, movement and transmission in their host plants. Simple control measures for avoiding disease spread are proposed. 2. Pecluviruses Both peanut clump viruses belong to the genus Pecluvirus, but formerly they were ascribed to the genus Furovirus sensu lato. The 0168-1702/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.virusres.2008.08.017