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This article belongs to the Special Issue Genetics and Genomics of Tomato and Solanaceae. ; High temperature is one of the most detrimental abiotic stresses in tomatoes. Many studies highlighted that even small increases in temperature can alter the plant reproductive system, causing a significant reduction in tomato yield. The aim of this study was to exploit the phenotypic and genomic variations of a tomato landrace collection grown at high temperatures. Fifteen genotypes were selected as the best performing in two experimental fields. The selection was based on six yield-related traits, including flower earliness, number of flowers per inflorescence, fruit set, number of fruit per plant, fruit weight and yield per plant. In order to identify markers targeting traits that could be highly influenced by adverse climate conditions, such as flowering and fruit setting, an association mapping approach was undertaken exploiting a tomato high-throughput genomic array. The phenotypic variability observed allowed us to identify a total of 15 common markers associated with the studied traits. In particular, the most relevant associations co-localized with genes involved in the floral structure development, such as the style2.1 gene, or with genes directly involved in the response to abiotic stresses. These promising candidate genes will be functionally validated and transferred to a cultivated tomato to improve its performance under high temperatures. ; The authors have received funding from the European Union's Horizon 2020 research and innovation programme through the TomGEM project under grant agreement No 679796. VR was supported by the European Union's Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement No 6655919. ; Peer reviewed

[Background]: Melon shows a broad diversity in fruit morphology and quality, which is still underexploited in breeding programs. The knowledge of the genetic basis of fruit quality traits is important for identifying new alleles that may be introduced in elite material by highly efficient molecular breeding tools. ; [Results]: In order to identify QTLs controlling fruit quality, a recombinant inbred line population was developed using two commercial cultivars as parental lines: "Védrantais", from the cantalupensis group, and "Piel de Sapo", from the inodorus group. Both have desirable quality traits for the market, but their fruits differ in traits such as rind and flesh color, sugar content, ripening behavior, size and shape. We used a genotyping-by-sequencing strategy to construct a dense genetic map, which included around five thousand variants distributed in 824 bins. The RIL population was phenotyped for quality and morphology traits, and we mapped 33 stable QTLs involved in sugar and carotenoid content, fruit and seed morphology and major loci controlling external color of immature fruit and mottled rind. The median confidence interval of the QTLs was 942 kb, suggesting that the high density of the genetic map helped in increasing the mapping resolution. Some of these intervals contained less than a hundred annotated genes, and an integrative strategy combining gene expression and resequencing data enabled identification of candidate genes for some of these traits. ; [Conclusion]: Several QTLs controlling fruit quality traits in melon were identified and delimited to narrow genomic intervals, using a RIL population and a GBS-based genetic map. ; This work was supported by the Spanish Ministry of Economy and Competitiveness grant AGL2015–64625-C2–1-R, Severo Ochoa Programme for Centres of Excellence in R&D 2016–2010 (SEV-2015-0533) and the CERCA Programme/Generalitat de Catalunya to JGM. LP was supported by a FPI grant from the Spanish Ministry of Economy and Competitiveness. VR was supported by the European Union's Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement No 6655919. ; Peer reviewed

Melon is as an alternative model to understand fruit ripening due to the coexistence of climacteric and non-climacteric varieties within the same species, allowing the study of the processes that regulate this complex trait with genetic approaches. We phenotyped a population of recombinant inbred lines (RILs), obtained by crossing a climacteric (Védrantais, cantalupensis type) and a non-climcteric variety (Piel de Sapo T111, inodorus type), for traits related to climacteric maturation and ethylene production. Individuals in the RIL population exhibited various combinations of phenotypes that differed in the amount of ethylene produced, the early onset of ethylene production, and other phenotypes associated with ripening. We characterized a major QTL on chromosome 8, ETHQV8.1, which is sufficient to activate climacteric ripening, and other minor QTLs that may modulate the climacteric response. The ETHQV8.1 allele was validated by using two reciprocal introgression line populations generated by crossing Védrantais and Piel de Sapo and analyzing the ETHQV8.1 region in each of the genetic backgrounds. A Genome-wide association study (GWAS) using 211 accessions of the ssp. melo further identified two regions on chromosome 8 associated with the production of aromas, one of these regions overlapping with the 154.1 kb interval containing ETHQV8.1. The ETHQV8.1 region contains several candidate genes that may be related to fruit ripening. This work sheds light into the regulation mechanisms of a complex trait such as fruit ripening. ; This work was supported by the Spanish Ministry of Economy and Competitiveness grants AGL2015–64625-C2–1-R and RTI2018-097665-B-C2, Severo Ochoa Programme for Centres of Excellence in R&D 2016–2010 (SEV-2015-0533) and the CERCA Programme/Generalitat de Catalunya to J.G.-M., L.P. and M.S.-D. were supported by a FPI grant from the Spanish Ministry of Economy and Competitiveness. V.R. was supported by the European Union's Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement No 6655919. Y.X. was supported by the China Agriculture Research System (CARS-25). ; Peer reviewed

We report an improved assembly (v3.6.1) of the melon (Cucumis melo L.) genome and a new genome annotation (v4.0). The optical mapping approach allowed correcting the order and the orientation of 21 previous scaffolds and permitted to correctly define the gap-size extension along the 12 pseudomolecules. A new comprehensive annotation was also built in order to update the previous annotation v3.5.1, released more than six years ago. Using an integrative annotation pipeline, based on exhaustive RNA-Seq collections and ad-hoc transposable element annotation, we identified 29,980 protein-coding loci. Compared to the previous version, the v4.0 annotation improved gene models in terms of completeness of gene structure, UTR regions definition, intron-exon junctions and reduction of fragmented genes. More than 8,000 new genes were identified, one third of them being well supported by RNA-Seq data. To make all the new resources easily exploitable and completely available for the scientific community, a redesigned Melonomics genomic platform was released at http://melonomics.net. The resources produced in this work considerably increase the reliability of the melon genome assembly and resolution of the gene models paving the way for further studies in melon and related species. ; This work was supported by the Spanish Ministry of Economy and Competitiveness grant AGL2015–64625-C2-1-R, Severo Ochoa Programme for Centres of Excellence in R&D 2016–2010 (SEV-2015–0533) and the CERCA Programme/Generalitat de Catalunya to JGM. VR was supported by the European Union's Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement No 665919. ; Peer reviewed