Copyright © 2016 IJAIR, All right reserved 481 International Journal of Agriculture Innovations and Research Volume 5, Issue 3, ISSN (Online) 2319-1473 Screening Improved Rice Varieties (Oryza spp) for their Resistance / Tolerance to Rice Yellow Mottle Virus in West Africa SEREME Drissa 1,4 , OUEDRAOGO Ibrahima 2 , NEYA Bouma James 1,4 , ZIDA Pawindé Elisabeth 3,4 , YAO Nasser 6 , SIE Moussa 5 1 Laboratoire de Virologie et de Biotechnologies Végétales, Institut de l’Environnement et de Recherches Agricoles (INERA), 01 BP 476 Ouagadougou 01, Burkina Faso 2 Laboratoire de phytopathologie, Institut de l’Environnement et de Recherches Agricoles (INERA), BP 910 Bobo-Dioulasso, Burkina Faso 3 Laboratoire de phytopathologie, Institut de l’Environnement et de Recherches Agricoles (INERA), 01 BP 476 Ouagadougou 01, Burkina Faso 4 Laboratoire Mixte International Patho-Bios (LMI Patho-Bios), 01 BP 476 Ouagadougou 01, Burkina Faso 5 AfricaRice, 01 BP 1690, Antananarivo, Madagascar 6 Biosciences eastern and central Africa-International Livestock Research Institute (BecA-ILRI), PO Box 30709, Nairobi, Kenya Corresponding author: Dr Drissa SEREME, Tel. (+226) 25 31 92 02 /08, Fax (+226) 25 31 92 75, E-mail :drissa.sereme@coraf.org Abstract – Rice yellow mottle virus (RYMV) is the most important rice-infecting virus in Africa. In the present study, sixteen improved rice varieties from Africa Rice and from the Environment and Agricultural Research Institute (INERA) of Burkina Faso were screened for their reaction to RYMV under greenhouse conditions. Rice seedlings were mechanically inoculated with anon-resistance-breaking but highly severe RYMV isolate. Screening was conducted by visual symptom scoring and virus-assessment through ELISA tests 31 dpi. The response to RYMV of 16 rice accessions was assessed. Disease incidence and severity were recorded. According to differences in these measured traits control cultivars IR 64, Azucena and Gigante were proved to be the most susceptible, tolerant and resistant ones, respectively. The result showed that five of the thirteen tested rice genotypes, were moderately to resistant to RYMV. The others eight were susceptible. The results suggested that rice germplasms from Africa Rice and INERA contain valuable germplasms resistant to RYMV, and the screened germplasms in the present study could provide promising resistance sources for rice breeding. These resistant and moderate resistant genotypes could be used by farmers in cultivation under integrated production systems and by breeders in developing new rice hybrid resistant genotypes to RYMV. Keywords – Rice Yellow Mottle Virus, Resistant, ELISA, Symptoms. I. INTRODUCTION As one of the most important diseases affecting rice in Africa, yellow mottle disease has become the most serious and prevalent diseases in West Africa in recent years. The causal agent is Rice yellow mottle virus (RYMV) of the plant virus genus Sobemovirus with five open reading frames (ORF) [1], [2]. RYMV was first detected in 1966 at Kisumu in Western Kenya near Lake Victoria [3]. It has since been observed and detected in almost all rice- producing countries of sub-Saharan Africa [4]. Symptoms induced by the virus are highly variable including leaf mottling and yellowing, stunting, reduced tillering, non-uniform flowering, and plant death. Disease severity depends on the rice genotype, the virus strain, the age of a plant at infection, and the climatic factors [3]. Today, six strains have been identified with specific geographical adaptations. Three strains, namely S1, S2, and S3, are found in West and Central Africa whereas S4, S5, S6 are present in East and Southern Africa [5],[6]. RYMV has a narrow host range restricted to the two cultivated rice species Oryza sativa and O. glaberrima, the wild rice species O. longistaminata and O. barthii, and a few other wild Poaceae species [3].Field studies have revealed the significant role of rice nurseries in the propagation of RYMV [7]. Movement of the virus over short distances by mammals has been reported [8] [9]. RYMV is transmitted by beetle species of the family Chrysomel idae [3]. Biological tests indicated that RYMV is not transmitted through seeds of rice [3], [10], [11], [12] and of wild host species [13].Crop damage by RYMV can be devastating causing variable yield losses that may reach 100% depending on the rice genotypes, infectious strain, stage of infection and environment [14], [15]. Management of RYMV is difficult and the common control practices are based on reducing vector population mainly by pesticides or physical barriers. Due to the large populations of insect vectors vector seclusion is not an ideal way of controlling the spread and damage induced by RYMV. Hence, development of genetic resistance in the rice host is the best solution for any virus problem such as RYMV, since it requires no chemical input and/or plant seclusion and may be stable and long-lasting. Current investigations have revealed three types of resistance to RYMV: partial natural resistance, high natural resistance, and resistance obtained through genetic transformation [16]. High resistance is associated with lack of symptom development, undetectable virus content and blockage of virus movement [17]. This resistance was reported in two O. sativa indica varieties and a few O. glaberrima of the Tog series [18], [19]. Partial resistance, characterized by a delay in virus accumulation and in symptom development is present in rice Oryza japonica cultivar (cv.) Azucena and a few other japonica cultivars [20]. Control of the disease through the development of transgenic plants has been investigated and some transgenic lines with a partial Manuscript Processing Details (dd/mm/yyyy) : Received : 06/12/2016 | Accepted on : 12/12/2016 | Published : 23/12/2016