Metabolic characterization of loci affecting sensory attributes in tomato allows an assessment of the influence of the levels of primary metabolites and volatile organic contents

Numerous studies have revealed the extent of genetic and phenotypic variation between both species and cultivars of tomato. Using a series of tomato lines resulting from crosses between a cherry tomato and three independent large fruit cultivar (Levovil, VilB, and VilD), extensive profiling of both central primary metabolism and volatile organic components of the fruit was performed. In this study, it was possible to define a number of quantitative trait loci (QTLs) which determined the levels of primary metabolites and/or volatile organic components and to evaluate their co-location with previously defined organoleptic QTLs. Correlation analyses between either the primary metabolites or the volatile organic compounds and organoleptic properties revealed a number of interesting associations, including pharmaceutical aroma–guaiacol and sourness–alanine, across the data set. Considerable correlation within the levels of primary metabolites or volatile organic compounds, respectively, were also observed. However, there was relatively little association between the levels of primary metabolites and volatile organic compounds, implying that they are not tightly linked to one another. A notable exception to this was the strong association between the levels of sucrose and those of a number of volatile organic compounds. The combined data presented here are thus discussed both with respect to those obtained recently from wide interspecific crosses of tomato and within the framework of current understanding of the chemical basis of fruit taste

Patterns of sequence polymorphism in the fleshless berry locus in cultivated and wild Vitis vinifera accessions

<p>Abstract</p> <p>Background</p> <p>Unlike in tomato, little is known about the genetic and molecular control of fleshy fruit development of perennial fruit trees like grapevine (<it>Vitis vinifera </it>L.). Here we present the study of the sequence polymorphism in a 1 Mb grapevine genome region at the top of chromosome 18 carrying the <it>fleshless berry </it>mutation (<it>flb</it>) in order, first to identify SNP markers closely linked to the gene and second to search for possible signatures of domestication.</p> <p>Results</p> <p>In total, 62 regions (17 SSR, 3 SNP, 1 CAPS and 41 re-sequenced gene fragments) were scanned for polymorphism along a 3.4 Mb interval (85,127-3,506,060 bp) at the top of the chromosome 18, in both <it>V. vinifera cv</it>. Chardonnay and a genotype carrying the <it>flb </it>mutation, <it>V. vinifera cv</it>. Ugni Blanc mutant. A nearly complete homozygosity in Ugni Blanc (wild and mutant forms) and an expected high level of heterozygosity in Chardonnay were revealed. Experiments using qPCR and BAC FISH confirmed the observed homozygosity. Under the assumption that <it>flb </it>could be one of the genes involved into the domestication syndrome of grapevine, we sequenced 69 gene fragments, spread over the <it>flb </it>region, representing 48,874 bp in a highly diverse set of cultivated and wild <it>V. vinifera </it>genotypes, to identify possible signatures of domestication in the cultivated <it>V. vinifera </it>compartment. We identified eight gene fragments presenting a significant deviation from neutrality of the Tajima's D parameter in the cultivated pool. One of these also showed higher nucleotide diversity in the wild compartments than in the cultivated compartments. In addition, SNPs significantly associated to berry weight variation were identified in the <it>flb </it>region.</p> <p>Conclusions</p> <p>We observed the occurrence of a large homozygous region in a non-repetitive region of the grapevine otherwise highly-heterozygous genome and propose a hypothesis for its formation. We demonstrated the feasibility to apply BAC FISH on the very small grapevine chromosomes and provided a specific probe for the identification of chromosome 18 on a cytogenetic map. We evidenced genes showing putative signatures of selection and SNPs significantly associated with berry weight variation in the <it>flb </it>region. In addition, we provided to the community 554 SNPs at the top of chromosome 18 for the development of a genotyping chip for future fine mapping of the <it>flb </it>gene in a F2 population when available.</p

Caractérisation des déterminants génétiques et moléculaires de composantes de la texture du fruit de tomate

Diplôme : Dr. d'UniversiteLa texture est un critère essentiel dans la perception de la qualité organoleptique du fruit de tomate. Cependant, il s’agit d’un caractère complexe dont les différentes composantes (fermeté, farinosité, jutosité) sont essentiellement évaluées par analyses sensorielles. L’objectif de la thèse est d’identifier des mécanismes contrôlant les variations de texture du fruit de tomate, tant au niveau génétique que moléculaire, afin de fournir, à long terme, des outils intéressants pour assister la sélection de ces caractères dans le cadre de l’innovation variétale. Au niveau génétique, la caractérisation des QTL de texture est abordée en cherchant à savoir comment les régions porteuses de QTL interagissent entre elles et comment le fonds génétique peut influencer l’expression de ces QTL. A l’exception de la fermeté, les effets des QTL de qualité ont été retrouvés au niveau des lignées quasi-isogéniques correspondantes dans le fonds génétique utilisé à l’origine pour la détection de QTL. Néanmoins, de fortes interactions entre QTL et fonds génétiques ont été mises en évidence ainsi qu’un effet fort de l’environnement sur l’expression de ces QTL. Parallèlement, la cartographie fine de deux régions où sont localisés des QTL associés à la texture, a été initiée. Les effets des QTL contrôlant la fermeté du fruit ont été détectés au niveau de certaines familles de recombinants et la localisation de ces QTL a été précisée. Au niveau moléculaire, la recherche de gènes candidats dont la fonction et/ou le niveau d’expression sont associés aux variations de texture a été réalisée par des analyses du protéome et du transcriptome. Plusieurs gènes candidats ont été identifiés et la cartographie de certains d’entre eux a révélé une co-localisation avec les QTL cibles

La transmission du récit et son héritage chez une famille palestinienne réfugiée à Chatila

International audienceThis research explores the transmission of exile narratives among the first generation of the Palestinian refugees in Chatila, Lebanon, and its inheritance to the younger generation. Children grow up in a context that had in the past witnessed raveled massacres. The Chatila camp represents a time and space unit hosting individual and collective issues entangled within one common and leaguing narrative. Supportive and protective modalities are found in resorting to the community and to individual heroic narration. The countenance offered within and by the group seems essential. The following generations have a restorative mandate toward their elders’ shattered history. Bound to reestablish honor and social status, they convey the land such a relic object. Within the third generation, the infantile and adolescent conflicts are coated with a discourse on loyalty to filiation and community.A Chatila, au Liban, les réfugiés palestiniens vivent dans un environnement hostile et les enfants grandissent dans ce cadre témoin des massacres passés, emmêlés. Une recherche a été menée afin de penser la transmission d’exils vécus par la première génération de réfugiés palestiniens ainsi que l’héritage reçu par la jeune génération. Comment les enjeux collectifs et individuels autour de la transmission d’une histoire commune sont apparus dans cette unité de temps et de lieu qu’est Chatila aujourd’hui ? Le recours au collectif et à la narration héroïque sont des modalités protectrices et étayantes. La contenance du groupe et par le groupe semble primordiale. En restituant un honneur et un statut social, en transportant une terre objet relique, les générations suivantes sont mandatées pour réparer les failles de leurs aînés. En effet, à la troisième génération, les problématiques infantiles et adolescentes semblent enrobées d’un discours coloré d’une loyauté filiative et communautaire

A Flashforward Look into Solutions for Fruit and Vegetable Production

One of the most important challenges facing current and future generations is how climate change and continuous population growth adversely affect food security. To address this, the food system needs a complete transformation where more is produced in non-optimal and space-limited areas while reducing negative environmental impacts. Fruits and vegetables, essential for human health, are high-value-added crops, which are grown in both greenhouses and open field environments. Here, we review potential practices to reduce the impact of climate variation and ecosystem damages on fruit and vegetable crop yield, as well as highlight current bottlenecks for indoor and outdoor agrosystems. To obtain sustainability, high-tech greenhouses are increasingly important and biotechnological means are becoming instrumental in designing the crops of tomorrow. We discuss key traits that need to be studied to improve agrosystem sustainability and fruit yield

The grape microvine - a model system for rapid forward and reverse genetics of grapevines

Contact:fax 61 8 83038601 [email protected] audienceP>A grapevine model system is described that is suitable for rapid forward and reverse genetic studies in small controlled environments. It is based on the Vvgai1 mutant allele that confers a dwarf stature, short generation cycles and continuous flowering ('microvine'). Black and white berry microvine genotypes were developed that can be transformed by Agrobacterium tumefaciens. Near-homozygous lines were created for efficient bi-allelic single nucleotide polymorphism (SNP) marker mapping and mutagenesis studies. A genetic mapping strategy based on picovine-derived microvine progeny populations was used to rapidly phenotype and map the flower sex and fleshless berry loci and identify a new lethal recessive locus, Vvlrl1. The microvine provides a unique model system for rapid genetic studies of grapevine by changing the perennial long life cycle of the plant to one with features and advantages similar to an annual plan

VviPLATZ1 is a major factor that controls female flower morphology determination in grapevine

International audiencePlant genetic sex determinants that mediate the transition to dioecy are predicted to be diverse, as this type of mating system independently evolved multiple times in angiosperms. Wild Vitis species are dioecious with individuals producing morphologically distinct female or male flowers; whereas, modern domesticated Vitis vinifera cultivars form hermaphrodite flowers capable of self-pollination. Here, we identify the VviPLATZ1 transcription factor as a key candidate female flower morphology factor that localizes to the Vitis SEX-DETERMINING REGION. The expression pattern of this gene correlates with the formation reflex stamens, a prominent morphological phenotype of female flowers. After generating CRISPR/Cas9 geneedited alleles in a hermaphrodite genotype, phenotype analysis shows that individual homozygous lines produce flowers with reflex stamens. Taken together, our results demonstrate that loss of VviPLATZ1 function is a major factor that controls female flower morphology in Vitis

Physiological relationships among physical, sensory, and morphological attributes of texture in tomato fruits

International audienceTomato texture is one of the critical components for the consumer's perception of fruit quality. Texture is a complex character composed of several attributes that are difficult to evaluate and which change during fruit ripening. This study investigated the texture of tomato fruits at the rheological, sensory, morphological, and genetic levels, and attempted to correlate several parameters. Analyses were performed on tomato fruits from introgressed lines carrying quantitative trait loci (QTLs) associated with texture traits localized on different chromosomes, in two genetic backgrounds. Rheological measurements were used to determine resistance to deformation and fruit elasticity. Sensory analysis was used to assess flesh firmness, juiciness, mealiness, and skin toughness. Image analysis was used to study fruit morphology and to define the cellular structure and heterogeneity of the pericarp. A highly significant correlation was observed between instrumental and sensory firmness. Moreover, correlations were also established between some texture traits and parameters of the pericarp cellular structure. Compared with QTLs detected in a previous study, the phenotypic effects expected for mealiness were confirmed in all lines, whereas, for firmness, they were not confirmed. Significant interactions between QTL and genetic background were observed for several traits. In addition, kinetic analysis showed that differences in firmness occurred from the early stages of fruit development. These results provide both a broad description of texture components and preliminary information to understand their genetic control