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Exploration du polymorphisme moléculaire et protéique de la tomate pour l’identification de QTL de qualité du fruit

Abstract : Fruit quality in tomato is highly dependent on genetic variation. Following domestication and modernbreeding, molecular diversity of tomato has been strongly reduced, limiting the possibility to improvetraits of interest. New molecular markers such as single nucleotide polymorphisms (SNP) constituteprecious tools to saturate tomato genetic maps and identify quantitative trait loci (QTL) andassociations in a poorly polymorphic species like tomato. The objectives of this study were tocharacterize tomato genetic diversity at the molecular levels and to try to identify QTLs, genes andproteins responsible for fruit quality traits in tomato. For this purpose, three independent studies wereconducted leading to the discovery of new SNP markers, their use for association study and finally theanalysis of proteome diversity in relation to physiological phenotypes. We first used two nextgenrationsequencing platforms (GA2 Illumina and 454 Roche) to re-sequence targeted sequencescovering about 0.2% of the tomato genome from two contrasted accessions. More than 3000 SNPswere identified between the two accessions. We then validated 64 SNPs by developing CAPS markers.We thus showed the value of NGS for the discovery of SNPs in tomato and we produced low costCAPS markers which could be used to characterize other tomato collections. A SNPlexTM arraycarrying 192 SNPs was then developed and used to genotype a broad collection of 188 accessionsincluding cultivated, cherry type and wild tomato species and to associate these polymorphisms to tenfruit quality traits using association mapping approach. A total of 40 associations were detected andco-localized with previously mapped QTLs. Some other associations were identified in new regions.We showed the potential of using association genetics in tomato. Finally, a new analytical approachcombining proteome, metabolome and phenotypic profiling were applied to study natural geneticvariation of fruit quality traits in eight diverse accessions and their four corresponding F1s at cellexpansion and orange-red stages. We identified 424 variable spots by combining 2-DE and nano LCMS/MS and built the first comprehensive proteome reference map of the tomato fruit pericarp at twodevelopmental stages from the 12 genotypes. In parallel, we measured the variation of 34 metabolites,26 enzyme activities and five phenotypic traits. A large range of variability and several inheritancemodes were described in the four groups of traits. Data integration was achieved through sPLS andcorrelation networks. Many significant associations were detected within level and between levels ofexpression. This systems biology approach provides better understanding of networks of elements(proteins, enzymes, metabolites and phenotypic traits) in tomato fruits
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  • HAL Id : tel-00927514, version 1
  • PRODINRA : 330142

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Jiaxin Xu. Exploration du polymorphisme moléculaire et protéique de la tomate pour l’identification de QTL de qualité du fruit. Sciences agricoles. Université d'Avignon, 2012. Français. ⟨NNT : 2012AVIG0644⟩. ⟨tel-00927514⟩

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