BackgroundA collection of 175 melon (Cucumis melo L.) accessions (including wild relatives, feral types, landraces, breeding lines and commercial cultivars) from 50 countries was selected to study the phenotypic variability for ripening behavior and sugar accumulation. The variability of single nucleotide polymorphisms (SNPs) at 53 selected candidate genes involved in sugar accumulation and fruit ripening processes was studied, as well as their association with phenotypic variation of related traits.ResultsThe collection showed a strong genetic structure, defining seven groups plus a number of accessions that could not be associated to any of the groups (admixture), which fitted well with the botanical classification of melon varieties. The variability in candidate genes for ethylene, cell wall and sugar-related traits was high and similar to SNPs located in reference genes. Variability at ripening candidate genes had an important weight on the genetic stratification of melon germplasm, indicating that traditional farmers might have selected for ripening traits during cultivar diversification. A strong relationship was also found between the genetic structure and phenotypic diversity, which could hamper genetic association studies. Accessions belonging to the ameri group are the most appropriate for association analysis given the high phenotypic and molecular diversity within the group, and lack of genetic structure.The most remarkable association was found between sugar content and SNPs in LG III, where a hotspot of sugar content QTLs has previously been defined. By studying the differences in allelic variation of SNPs within horticultural groups with specific phenotypic features, we also detected differential variation in sugar-related candidates located in LGIX and LGX, and in ripening-related candidates located in LGII and X, all in regions with previously mapped QTLs for the corresponding traits.ConclusionsIn the current study we have found an important variability at both the phenotypic and candidate gene levels for ripening behavior and sugar accumulation in melon fruit. By combination of differences in allelic diversity and association analysis, we have identified several candidate genes that may be involved in the melon phenotypic diversity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-015-0183-2) contains supplementary material, which is available to authorized users.

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EU border regions continue to face economic and social disadvantages compared to other regions in the same country. Since 1990, the European Commission has been implementing extensive territorial cooperation programs to support EU border regions in solving regional problems and building social cohesion. This study offers a contribution for decreasing the economic and social disadvantages of EU border regions by investigating the complementarity between institutional EU cross-border cooperation and social entrepreneurship. We argue that both concepts build upon similar drivers and characteristics with the aim of creating impact and bringing about change. We test and improve our initially literature-based framework to provide a better insight into how institutional and entrepreneurial processes could benefit from each other. We conduct interviews with experts operating at different governance levels and in various EU countries and border regions. The complementarity between both concepts is confirmed considering a differentiation between governance levels and fields of expertise. The results show that complementarity between the concepts mainly exists in terms of taking advantage of opportunities for a certain effect. The commercial activities of social enterprises are seen as effective, but it is necessary for social enterprises to establish sustainable EU cross-border cooperation and to improve regional social and economic development.

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