Melon fruit quality: a genomic approach.

Genomic resources, including large-scale sequencing, whole genome transcriptome analyses, and fine-scale genetic mapping, enable new insights into entire networks determining fruit quality. Molecular biology was introduced into melon fruit quality studies almost 15 years ago beginning with several breakthroughs: (1) the cloning and knockout of a gene involved in the regulation of fruit ripening, (2) the isolation and characterization of additional genes associated with fruit ripening and quality, and (3) the first genetic map that included molecular markers. Subsequent advances in molecular techniques led to the rapid development of genomic and metabolomic resources for melon and other cucurbits. The impact of this progress on the application to fruit quality improvement is just beginning to emerge. This is an overview of the current knowledge related to some of the major metabolic pathways associated with melon fruit quality and the genomic tools that are being developed. OVERVIEW Fruit quality is determined by complex networks of metabolic pathways developed during fruit ripening. Melon (Cucumis melo L.) comprises a broad array of genotypes, in which the fruit accumulate soluble sugars, organic acids, secondary metabolites of pigmentation and aroma volatiles to varying levels. Furthermore, C. melo includes fruit differing in ripening physiology, levels of ascorbic acid, additional identified and non-identified secondary metabolites and other biochemical components of quality. Current knowledge of these pathways is based on studies combining genetic, biochemical, and physiological approaches (for reviews see Burger et al. 2006; Grumet et al. 2007; Pech et al. 2008 and references within). In recent years, genomic and metabolomic approaches enhanced our understanding of the genes and metabolites that affect quality traits. Beginning 15 years ago, several contributions marked this new research era: (1) the cloning and suppression of the ACO 1 gene (Balague et al. 1993; Ayub et al. 1996), (2) the first differential screening Cucurbitaceae 2008, Proceedings of the IX EUCARPIA meeting on genetics and breeding of Cucurbitaceae (Pitrat M, ed), INRA, Avignon (France), May 21-24, 2008

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