Poulicard Nils auteur aut IRD Galzi Agnès auteur aut IRD Traore O. auteur aut IRD Vignols F. auteur aut IRD Ghesquière Alain auteur aut IRD Konate G. auteur aut IRD Hébrard Eugénie auteur aut IRD Fargette Denis auteur aut IRD text journalArticle eng text/pdf reformatted digital access The rymv1-2 and rymv1-3 alleles of the RYMV1 resistance to Rice yellow mottle virus (RYMV), coded by an eIF(iso) 4G1 gene, occur in a few cultivars of the Asiatic (Oryza sativa) and African (O. glaberrima) rice species, respectively. The most salient feature of the resistance breaking (RB) process is the converse genetic barrier to rymv1-2 and rymv1-3 resistance breakdown. This specificity is modulated by the amino acid (glutamic acid vs. threonine) at codon 49 of the Viral Protein genome-linked (VPg), a position which is adjacent to the virulence codons 48 and 52. Isolates with a glutamic acid (E) do not overcome rymv1-3 whereas those with a threonine (T) rarely overcome rymv1-2. We found that isolates with T49 had a strong selective advantage over isolates with E49 in O. glaberrima susceptible cultivars. This explains the fixation of the mutation T49 during RYMV evolution and accounts for the diversifying selection estimated at codon 49. Better adapted to O. glaberrima, isolates with T49 are also more prone than isolates with E49 to fix rymv1-3 RB mutations at codon 52 in resistant O. glaberrima cultivars. However, subsequent genetic constraints impaired the ability of isolates with T49 to fix rymv1-2 RB mutations at codons 48 and 52 in resistant O. sativa cultivars. The origin and role of the amino acid at codon 49 of the VPg exemplifies the importance of historical contingencies in the ability of RYMV to overcome RYMV1 resistance. specialized AFRIQUE SUBSAHARIENNE MADAGASCAR 076 8 1 e1002482 2012 1553-7366 https://www.documentation.ird.fr/hor/fdi:010055667 10.1371/journal.ppat.1002482 1553-7366 [F B010055667] https://www.documentation.ird.fr/hor/fdi:010055667 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers15-10/010055667.pdf IRD - Base Horizon / Pleins textes 2012-04-04 2021-06-07 fdi:010055667 fre