title: Identification of a second major resistance gene to Rice yellow mottle virus, RYMV2, in the African cultivated rice species, O. glaberrima.
abstract: Rice yellow mottle virus (RYMV) is the most damaging rice-infecting virus in Africa. However, few sources of high resistance and only a single major resistance gene, RYMV1, are known to date. We screened a large representative collection of African cultivated rice (Oryza glaberrima) for RYMV resistance. Whereas high resistance is known to be very rare in Asian cultivated rice (Oryza sativa), we identified 29 (8%) highly resistant accessions in O. glaberrima. The MIF4G domain of RYMV1 was sequenced in these accessions. Some accessions possessed the rymv1-3 or rymv1-4 recessive resistance alleles previously described in O. glaberrima Tog5681 and Tog5672, respectively, and a new allele, rymv1-5, was identified, thereby increasing the number of resistance alleles in O. glaberrima to three. In contrast, only a single allele has been reported in O. sativa. Markers specific to the different alleles of the RYMV1 gene were developed for marker-assisted selection of resistant genotypes for disease management. In addition, the presence of the dominant susceptibility allele (Rymv1-1) in 15 resistant accessions suggests that their resistance is under different genetic control. An allelism test involving one of those accessions revealed a second major resistance gene, i.e., RYMV2. The diversity of resistance genes against RYMV in O. glaberrima species is discussed in relation to the diversification of the virus in Africa.
authors.affiliation: Laboratoire Génome et Développement des Plantes, Unité Mixte de Recherche 5096, Université de Perpignan via Domitia, CNRS, IRD, BP 64501, 34394, Montpellier Cedex 5, France.
authors.forename: Deless
authors.initials: D
authors.lastname: Thiémélé
authors.forename: Arnaud
authors.initials: A
authors.lastname: Boisnard
authors.forename: Marie-Noëlle
authors.initials: MN
authors.lastname: Ndjiondjop
authors.forename: Sophie
authors.initials: S
authors.lastname: Chéron
authors.forename: Yacouba
authors.initials: Y
authors.lastname: Séré
authors.forename: Séverin
authors.initials: S
authors.lastname: Aké
authors.forename: Alain
authors.initials: A
authors.lastname: Ghesquière
authors.forename: Laurence
authors.initials: L
authors.lastname: Albar
mesh_terms: D000349:Africa; D000483:Alleles; D000595:Amino Acid Sequence; D018556:Crops, Agricultural / Q000235:genetics / Q000276:immunology / Q000821:virology; D017343:Genes, Plant; D005819:Genetic Markers; D007113:Immunity, Innate / Q000235:genetics*; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000276:immunology / Q000821:virology; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000821:virology; D010942:Plant Viruses / Q000276:immunology / Q000472:pathogenicity*
chemical_list: D005819:Genetic Markers