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International audience; Tomato is a widely cultivated crop, which can grow in many environments. However, temperature above 30 degrees C impairs its reproduction, subsequently impacting fruit yield. We assessed the impact of high-temperature stress (HS) in two tomato experimental populations, a multi-parental advanced generation intercross (MAGIC) population and a core-collection (CC) of small-fruited tomato accessions. Both populations were evaluated for 11 traits related to yield components, phenology and fruit quality in optimal and HS conditions. HS significantly impacted all traits in both populations, but a few genotypes with stable yield under HS were identified. A plasticity index was computed for each individual to measure the extent of the heat impact for each trait. Quantitative trait loci (QTL) were detected in control and HS conditions as well as for plasticity index. Linkage and genome-wide association analyses in the MAGIC and CC populations identified a total of 98 and 166 QTLs, respectively. Taking the two populations together, 69 plasticity QTLs (pQTLs) were involved in tomato heat response for 11 traits. The transcriptome changes in the ovary of six genotypes with contrasted responses to HS were studied, and 837 genes differentially expressed according to the conditions were detected. Combined with previous transcriptome studies, these results were used to propose candidate genes for HS response QTLs.

International audience; Tomato (Solanum lycopersicum) is the model species for studying fleshy fruit development. An extensive proteome map of the fruit pericarp is described in light of the high-quality genome sequence. The proteomes of fruit pericarp from 12 tomato genotypes at two developmental stages (cell expansion and orange-red) were analyzed. The 2DE reference map included 506 spots identified by nano-LC/MS and the International Tomato Annotation Group Database searching. A total of 425 spots corresponded to unique proteins. Thirty-four spots resulted from the transcription of genes belonging to multigene families involving two to six genes. A total of 47 spots corresponded to a mixture of different proteins. The whole protein set was classified according to Gene Ontology annotation. The quantitative protein variation was analyzed in relation to genotype and developmental stage. This tomato fruit proteome dataset is currently the largest available and constitutes a valuable tool for comparative genetic studies of tomato genome expression at the protein level. All MS data have been deposited in the ProteomeXchange with identifier PXD000105.

International audience; Sensory properties are important elements to evaluate the qualities of vegetable products and are also determinant factors in purchasing decision. Here we report the Italian results of a preference mapping study conducted within a larger European project with the aim of describing the preferences of European consumers in regard to the diversity of traditional and modern tomato varieties, available on the market. This study has allowed the assessment of fruit quality at 3 levels: objective description of sensory properties, consumer preference tests, and physicochemical measurements. A set of 16 tomato cultivars, with different fruit sizes and shapes, was described and classified according to 18 sensory attributes including flavor, appearance, and texture characteristics. The same cultivars were evaluated by 179 consumers in a “preference mapping” experiment with the goal of identifying the preferred varieties and the reasons for the choice. The consumer data are referred to hedonic ratings (aspect liking and overall liking), familiarity for the analyzed cultivars, and individual features collected by a questionnaire. A hierarchical analysis of the clusters allowed to distinguish, within the sampled Italian consumers, 4 segments with different preferences which represented 19%, 25%, 41%, and 15% of the population, respectively. A partial least square regression model allowed the identification of the sensory attributes that best described consumer cluster preferences for tomato cultivars. Both texture and flavor descriptors were important drivers of consumer preferences, but the relevance (predictive value) of individual descriptors to model tomato liking was different for each consumer segment. Information on demographic and behavioral characteristics, usage habits, and factors relevant for purchasing were also provided on the 4 groups of consumers.

Summary Determining gene sequences responsible for complex phenotypes has remained a major objective in modern biology. The candidate gene approach is attempting to link, through mapping analysis, sequences that have a known functional role in the measured phenotype with quantitative trait loci (QTL) that are responsible for the studied variation. To explore the potential of the candidate approach for complex traits we conducted a mapping analysis of QTL for the intensity of the red colour of the tomato fruit (mainly lycopene) and for probes associated with the well-characterized carotenoid biosynthesis pathway. Seventy-five tomato introgression lines (ILs), each containing a single homozygous RFLP-defined chromosome segment from the green-fruited species Lycopersicon pennellii delimited 107 marker-defined mapping bins. Three of the bins resolved known qualitative colour mutations for yellow (r) and orange (B and Del) fruits resulting from variation in specific carotenoid biosynthesis genes. Based on trials in different environments, 16 QTL that modified the intensity of the red colour of ripe fruit were assigned to bins. Candidate sequences associated with the carotenoid biosynthesis pathway were mapped to 23 loci. Only five of the QTL co-segregated with the same bins that contained candidate genes – a number that is expected by chance alone. Furthermore, similar map location of a QTL and a candidate is far from a direct causative relationship between a gene and a phenotype. This study highlights the wealth and complexity of the variation present in the genus Lycopersicon that could be employed for basic research and genetic improvement of fruit colour in tomato.