Evolutionary dynamics of a locus of fertility restoration in plants Jos´ e R. Hern´ andez Mora ⋆ 1 , Eric Rivals ⋆ 2 , Hakim Mireau 1 , Franc ¸oise Budar 1 1 Station de G´ en´ etique et d’Am´ elioration des Plantes - IJPB INRA, route de Saint Cyr, 78026 Versailles, France budar@versailles.inra.fr 2 Laboratoire d’Informatique de Robotique et de Micro´ electronique de Montpellier (LIRMM) Univ. Montpellier II - CNRS 161 rue Ada, 34392 Montpellier, Cedex 5, France {rivals}@lirmm.fr Abstract: In higher plants, hermaphrodites may genetically loose their male fertility through the cytoplasmic male sterility (CMS) system. In radish, a nuclear locus, denoted Rfo, has evolved that is able to counteract the effect of CMS and restore the fertility. This locus encodes three similar genes in tandem that belong to the pentatricopeptide repeat (PPR) family and each gene encloses a tandem repeat of PPR motif. Among the hundreds of members of this family, some play a role in the post-transcriptional gene regulation in organelles (mitochondria and chloroplasts). In this study, we recently sequenced a European non-restorer allelic locus and compare it to the original Rfo restorer allele to investigate its evolutionary dynamics. We conducted bioinformatic analysis to determine the putative border of tandem duplications both at protein motif level and at gene level. Our results present the picture of complex evolution with multiple gene duplications at a fast evolving locus. Keywords: PPR, duplication, tandem repeat, plant genomic, bioinformatic analysis, Rfo locus, radish 1 Introduction In higher plants, cytoplasmic genes can sometimes prevent the formation of pollen, thus transform- ing hermaphrodites into females (i.e., sterile males). The presence of nuclear genes named Restor- ers of fertility (Rf) allow the production of pollen in the presence of a male sterility-inducing cyto- plasm. This control of the sexual phenotype in plants is knowned as nuclear-cytoplasmic male sterility (CMS). CMS systems are constituted of two actors: a mitochondrial protein that causes male sterility, and a nuclear gene that encodes a mitochondria-targeted protein able to impair the expression of the sterility gene. All Rf genes identified so far (with the only exception of the Rf2 Texas maize restorer) belong to the pentatricopeptide repeat (PPR) family [1,2]. The Rfo locus, first described in Asian radish cultivars and later introduced into Brassica, is involved in the restoration of fertility in the Ogura CMS system. The nuclear restorer gene in the Rfo- Ogura system also encodes a protein belonging to the pentatricopeptide repeat (PPR) family [1,2]. The PPR gene family is a very large family in plants, with about 450 members in A. thaliana. Their function is largely unknown, although some members proved to be involved in post-transcriptional organelle gene regulation [3]. ⋆ J.R.H and E.R. equally contributed to this work lirmm-00343902, version 1 - 3 Dec 2008 Author manuscript, published in "JOBIM'08: Journées Ouvertes en Biologie, Informatique et Mathématiques, Lille? France : (2008)"