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Identification of natural allelic variants underlying nitrogen assimilation differences in a multiparent intercross yeast population

Cubillos F.A., García V., Abarca V., Araos S., Moulinet J., Brice C., Tisne S., Liti G., Martínez C.. 2015. Yeast, 32 : p. S150-S150. International Conference on Yeast Genetics and Molecular Biology. 27, 2015-09-06/2015-09-12, Levico Terme (Italie).

Most traits, including many oenological phenotypes, are complex and regulated by multiple interacting quantitative trait loci. The first step towards accurate models of trait variability, and a prerequisite for predicting and modulating them, is characterisation of the underlying genetic factors. In this context, nitrogen assimilation preferences during wine fermentation represent a complex trait of industrial interest. The nitrogen assimilation profile of each strain has a great importance on the fermentation kinetics, where low nitrogen concentrations in must can lead to sluggish or stuck fermentations, causing important economic losses. In order to identify allelic variants underlying nitrogen assimilation differences between the main representative S. cerevisiae strains, we performed QTL mapping and bulk segregant transcriptome analysis in 169 individuals from the multiparent SGRP-4X mapping population. For this, we estimated nitrogen consumption levels at the end of the fermentation process and performed QTL mapping utilizing nitrogen consumption levels for 14 amino acids and ammonium. Overall, we mapped 27 QTLs for the different nitrogen sources with a stringent LOD score above 8. Among these QTLs we have selected more than 10 candidate genes to validate through a reciprocal hemizygosity approach. In parallel, we also performed a transcriptome analysis on bulks of segregants with extreme nitrogen assimilation profiles for ammonium and glutamine consumption. Altogether, our results extend the currently known catalogue of natural variants underlying nitrogen assimilation differences, representing a useful tool to generate more efficient strains for the wine industry. (Texte intégral)

Mots-clés : phénotype; saccharomyces; glutamine; ammonium; cartographie; locus des caractères quantitatifs; allèle; variation génétique; marqueur génétique; vinification; levure de vinification; fermentation; fixation de l'azote; viticulture; qtl

Thématique : Génétique et amélioration des plantes; Physiologie végétale : nutrition

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