Deciphering the Theobroma cacao self-incompatibility system: from genomics to diagnostic markers for self-compatibility

Lanaud Claire, Fouet Olivier, Legavre Thierry, Lopes Uilson Vanderlei, Sounigo Olivier, Eyango Marie Claire, Mermaz Benoit, da Silva Marcos Ramos, Loor Solorzano Rey Gaston, Argout Xavier, Gyapay Gabor, Ebaiarrey Herman Ebai, Colonges Kelly, Sanier Christine, Rivallan Ronan, Mastin Géraldine, Cryer Nicholas, Boccara Michel, Verdeil Jean-Luc, Efombagn Mousseni Ives Bruno, Peres Gramacho Karina, Clément Didier. 2017. Deciphering the Theobroma cacao self-incompatibility system: from genomics to diagnostic markers for self-compatibility. Journal of Experimental Botany, 68 (17) : 4775-4790.

https://doi.org/10.1093/jxb/erx293

Article de revue ; Article de recherche ; Article de revue à facteur d'impact

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Quartile : Q1, Sujet : PLANT SCIENCES

Résumé : Cocoa self-compatibility is an important yield factor and has been described as being controlled by a late gameto-sporophytic system expressed only at the level of the embryo sac. It results in gametic non-fusion and involves several loci. In this work, we identified two loci, located on chromosomes 1 and 4 (CH1 and CH4), involved in cocoa self-incompatibility by two different processes. Both loci are responsible for gametic selection, but only one (the CH4 locus) is involved in the main fruit drop. The CH1 locus acts prior to the gamete fusion step and independently of the CH4 locus. Using fine-mapping and genome-wide association studies, we focused analyses on restricted regions and identified candidate genes. Some of them showed a differential expression between incompatible and compatible reactions. Immunolocalization experiments provided evidence of CH1 candidate genes expressed in ovule and style tissues. Highly polymorphic simple sequence repeat (SSR) diagnostic markers were designed in the CH4 region that had been identified by fine-mapping. They are characterized by a strong linkage disequilibrium with incompatibility alleles, thus allowing the development of efficient diagnostic markers predicting self-compatibility and fruit setting according to the presence of specific alleles or genotypes. SSR alleles specific to self-compatible Amelonado and Criollo varieties were also identified, thus allowing screening for self-compatible plants in cocoa populations.

Mots-clés Agrovoc : Theobroma cacao, gène, marqueur génétique, carte génétique, expression des gènes, immunologie, Autostérilité, autocompatibilité, génomique, identification, locus, physiologie de la reproduction, génotype