Resultados de la solución

The combination of molecular breeding and metabolomics might build into a strong approach for the generation of pepper cultivars that combine high yield and enhanced field performance with improved quality attributes. The complete pepper genome has been sequenced and published (Kim et al. 2014). Although the annotation of the pepper genome is limited to gene family analysis and a more detailed characterization of selected genes involved in regulation of fruit ripening,

ethylene synthesis and capsaicinoid biosynthesis in hot pepper (Kim et al. 2014), it is clear that this genome sequence will strongly aid to the identification of key genes that underlie important agronomic traits. Metabolomics-assisted molecular breeding depends on such advancements in DNA sequencing, since it allows the identification of the genes and alleles underlying metabolite-driven traits. The responsible genes are the best possible genetic markers and are invaluable tools in a precision breeding strategy, aimed at efficient trait selection, while minimizing unwanted linkage drag. The present thesis revealed valuable insight into the genomic regions important for the production of (secondary) metabolites in pepper fruit. Confirmation of the results using a candidate gene approach, in which flavonoid mQTL, gene expression (eQTL) and candidate gene marker data were combined, provided valuable insight in the molecular regulation of the flavonoid pathway in pepper fruit. Having these sets of information will help breeders to monitor and select pepper cultivars with improved flavonoid levels.

Apart from quality attributes, metabolites are important for the induction of resistances against abiotic stresses and biotic pathogens (Aloni et al. 2008; Park et al. 2012; Schulze and Spiteller 2009). Various pathogens influence plant metabolism and do affect the composition of metabolites in fruits. For example, the polyphenol content in yellow bell pepper fruits changes after an infection with the fungus Colletotrichum gloeosporioides, which causes anthracnose (Park et al.

2012). In countries such as Indonesia, many abiotic and biotic stresses are a major reason for a low yield of pepper fruits. The typical climatic conditions with high temperatures and high humidity easily lead to many different stress responses which negatively affect production. These particular conditions challenge breeders to aim for developing cultivars that combine the various quality attributes and that are active also under the very stressful conditions in the tropic regions of the world. It requires more experiments to fully understand the phenotypic and genotypic interactions under the various environmental conditions. A deeper and more mechanistic understanding of the regulatory networks that control metabolite composition in fruits is important to dissect the various metabolic pathways and is essential for the further advancement of metabolic-assisted breeding programs.

This thesis shows that metabolomics-assisted breeding in combination with genetic analysis helps to identify markers and genes that underlie key steps in metabolite biosynthesis. Such information may steer breeding programs to introduce metabolite quality traits in commercial pepper cultivars. Deciding which metabolites are important for both farmers and consumers will be the breeders’

consideration for the future. This will require a close collaboration among all

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stakeholders, including farmers, consumers, biochemists, geneticists and breeding specialists from research institutes and universities as well as seed companies.

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SUMMARY