Background: The non-climacteric 'Yellow' melon (Cucumis melo, inodorus group) is an economically important crop and its quality is mainly determined by the sugar content. Thus, knowledge of sugar metabolism and its related pathways can contribute to the development of new field management and post-harvest practices, making it possible to deliver better quality fruits to consumers.Results: The RNA-seq associated with RT-qPCR analyses of four maturation stages were performed to identify important enzymes and pathways that are involved in the ripening profile of non-climacteric 'Yellow' melon fruit focusing on sugar metabolism. We identified 895 genes 10 days after pollination (DAP)-biased and 909 genes 40 DAP-biased. The KEGG pathway enrichment analysis of these differentially expressed (DE) genes revealed that 'hormone signal transduction', 'carbon metabolism', 'sucrose metabolism', 'protein processing in endoplasmic reticulum' and 'spliceosome' were the most differentially regulated processes occurring during melon development. In the sucrose metabolism, five DE genes are up-regulated and 12 are down-regulated during fruit ripening. Conclusions:The results demonstrated important enzymes in the sugar pathway that are responsible for the sucrose content and maturation profile in non-climacteric 'Yellow' melon. New DE genes were first detected for melon in this study such as invertase inhibitor LIKE 3 (CmINH3), trehalose phosphate phosphatase (CmTPP1) and trehalose phosphate synthases (CmTPS5, CmTPS7, CmTPS9). Furthermore, the results of the protein-protein network interaction demonstrated general characteristics of the transcriptome of young and full-ripe melon and provide new perspectives for the understanding of ripening.

Background: The non-climacteric ‘Yellow’ melon ( Cucumis melo , inodorus group) is an economically important crop and its quality is mainly determined by the sugar content. Thus, knowledge of sugar metabolism and its related pathways can contribute to the development of new field management and post-harvest practices, making it possible to deliver better quality fruits to consumers. Results: The RNA-seq associated with RT-qPCR analyses of four maturation stages were performed to identify important enzymes and pathways that are involved in the ripening profile of non-climacteric ‘Yellow’ melon fruit focusing on sugar metabolism. We identified 895 genes 10 days after pollination (DAP)-biased and 909 genes 40 DAP-biased. The KEGG pathway enrichment analysis of these differentially expressed (DE) genes revealed that ‘hormone signal transduction’, ‘carbon metabolism’, ‘sucrose metabolism’, ‘protein processing in endoplasmic reticulum’ and ‘spliceosome’ were the most differentially regulated processes occurring during melon development. In the sucrose metabolism, five DE genes are up-regulated and twelve are down-regulated during fruit ripening. Conclusions: The results demonstrated important enzymes in the sugar pathway that are responsible for the sucrose content and maturation profile in non-climacteric ‘Yellow’ melon. New DE genes were first detected for melon in this study such as invertase inhibitor LIKE 3 ( CmINH3 ), trehalose phosphate phosphatase ( CmTPP1 ) and trehalose phosphate synthases ( CmTPS5 , CmTPS7 , CmTPS9 ). Furthermore, the results of the protein-protein network interaction demonstrated general characteristics of the transcriptome of young and full-ripe melon and provide new perspectives for the understanding of ripening.

Background: The non-climacteric ‘Yellow’ melon ( Cucumis melo , inodorus group) is an economically important crop and its quality is mainly determined by the sugar content. Thus, knowledge of sugar metabolism and its related pathways can contribute to the development of new field management and post-harvest practices, making it possible to deliver better quality fruits to consumers. Results: The RNA-seq associated with RT-qPCR analyses of four maturation stages were performed to identify important enzymes and pathways that are involved in the ripening profile of non-climacteric ‘Yellow’ melon fruit focusing on sugar metabolism. We identified 895 genes 10 days after pollination (DAP)-biased and 909 genes 40 DAP-biased. The KEGG pathway enrichment analysis of these differentially expressed (DE) genes revealed that ‘hormone signal transduction’, ‘carbon metabolism’, ‘sucrose metabolism’, ‘protein processing in endoplasmic reticulum’ and ‘spliceosome’ were the most differentially regulated processes occurring during melon development. In the sucrose metabolism, five DE genes are up-regulated and twelve are down-regulated during fruit ripening. Conclusions: The results demonstrated important enzymes in the sugar pathway that are responsible for the sucrose content and maturation profile in non-climacteric ‘Yellow’ melon. New DE genes were first detected for melon in this study such as invertase inhibitor LIKE 3 ( CmINH3 ), trehalose phosphate phosphatase ( CmTPP1 ) and trehalose phosphate synthases ( CmTPS5 , CmTPS7 , CmTPS9 ). Furthermore, the results of the protein-protein network interaction demonstrated general characteristics of the transcriptome of young and full-ripe melon and provide new perspectives for the understanding of ripening.

Background: The non-climacteric ‘Yellow’ melon ( Cucumis melo , inodorus group) is an economically important crop and its quality is mainly determined by the sugar content. Thus, knowledge of sugar metabolism and its related pathways can contribute to the development of new field management and post-harvest practices, making it possible to deliver better quality fruits to consumers. Results: The RNA-seq associated with RT-qPCR analyses of four maturation stages were performed to identify important enzymes and pathways that are involved in the ripening profile of non-climacteric ‘Yellow’ melon fruit focusing on sugar metabolism. We identified 895 genes 10 days after pollination (DAP)-biased and 909 genes 40 DAP-biased. The KEGG pathway enrichment analysis of these differentially expressed (DE) genes revealed that ‘hormone signal transduction’, ‘carbon metabolism’, ‘sucrose metabolism’, ‘protein processing in endoplasmic reticulum’ and ‘spliceosome’ were the most differentially regulated processes occurring during melon development. In the sucrose metabolism, five DE genes are up-regulated and twelve are down-regulated during fruit ripening. Conclusions: The results demonstrated important enzymes in the sugar pathway that are responsible for the sucrose content and maturation profile in non-climacteric ‘Yellow’ melon. New DE genes were first detected for melon in this study such as invertase inhibitor LIKE 3 ( CmINH3 ), trehalose phosphate phosphatase ( CmTPP1 ) and trehalose phosphate synthases ( CmTPS5 , CmTPS7 , CmTPS9 ). Furthermore, the results of the protein-protein network interaction demonstrated general characteristics of the transcriptome of young and full-ripe melon and provide new perspectives for the understanding of ripening.

Background: The non-climacteric ‘Yellow’ melon (Cucumis melo, inodorus group) is an economically important crop and its quality is mainly determined by the sugar content. Thus, the knowledge of sugar metabolism and its related pathways can contribute to development of new field management and post-harvest practices, making it possible to deliver to consumers better quality fruits.Results: The RNA-seq associated with RT-qPCR analyses of four maturation stages were performed to identify important enzymes and pathways that are involved in the sugar metabolism profile in non-climacteric ‘Yellow’ melon fruit. We identified 895 genes 10 DAP-biased and 909 genes 40 DAP-biased. The global analyses evidenced pathways related to sucrose metabolism; hormone signal transduction; DNA and protein processing like significant metabolisms in the melon ripening. For fruit sucrose metabolism, 17 genes were differentially expressed (DE) whose pattern varied throughout fruit development.Conclusions: The results demonstrated important enzymes in the sugar pathway those are responsible for the sucrose content and maturation profile in non-climacteric ‘Yellow’ melon. New DE genes were first detected for melon in this study such as invertase inhibitor LIKE 3 (CmINH3), trehalose phosphate phosphatase (CmTPP1) and trehalose phosphate synthases (CmTPS5, CmTPS7, CmTPS9). Besides that, the results of the protein-protein network interaction demonstrated general characteristics of the transcriptome of young and full-ripe melon. Keywords: Cucumis melo, RNA-seq, sucrose, fruit ripening, gene expression

Melon (Cucumis melo L.) is an important species in the cucurbits family with a large economic importance in the world. Two melon cultivars commercially important in Brazil are the cultivars ‘Yellow’ and ‘Gaúcho’. In addition to the economic importance, these two cultivars display phenotypic differences in aroma, a major trait determining fruit quality. Volatile organic compounds (VOC) impart the different aroma found in these fruit and its biosynthesis is associated with fatty acid and amino acid metabolism. Using SPME-GC–MS and RT-qPCR techniques, volatile production and expression of seven genes (CmLOX9, CmLOX18, CmBCAT1, CmArAT1, CmPDC1, CmADH1 and CmAAT1) were determined during maturation and ripening. The climacteric melon ‘Gaúcho’ had a greater number and higher concentration of volatiles than that in the non-climacteric ‘Yellow’ melon. 2-Methylallyl acetate, 4-amino-1-butanol, 2-methylbutanol and ethyl 2-methylpropanoate were found in high concentrations in ripe climacteric ‘Gaúcho’ melons and were major contributors to its strong fruity aroma, but high concentrations of these volatiles were not found in non-climacteric ‘Yellow’ melons. The lipid pathway played a strong role in determining aroma composition in non-climacteric ‘Yellow’ melons. Most volatiles decreased during maturation and ripening explaining the non-aromatic characteristic of this cultivar. In climacteric ‘Gaúcho’ melons, the amino acid pathway was the main one related to the biosynthesis of esters, which contribute to the aroma of this cultivar. Volatile products of the branched chain amino acid pathway correlated with CmADH1 and CmAAT1 expression demonstrating their role in volatile synthesis of this climacteric melon cultivar. In addition, CmPDC1 contributes to the formation of aldehydes at the beginning of this pathway.