Construction of linkage maps and analysis of QTL linked to phenology and fruit quality traits in two apricot progenies combining SSRs and SNPs

Ten important pomological traits, including blooming date, ripening time, fruit development period, fruit weight, fruit colour, fruit diameter, stone weight, firmness, soluble solids content and acidity, related to tree phenology and fruit quality were studied during three years in two F1 apricot progenies derived from the crosses 'Bergeron' × 'Currot' (B×C) and 'Goldrich' × 'Currot' (G×C). Results showed a great variability and segregation in each population confirming the polygenic nature and quantitative inheritance for all the studied traits. In addition, genetic linkage maps were constructed combining SSR and SNP markers, using 87 markers in the B×C population and 89 markers in G×C. SNPs were designed from cDNAs (RNA-Seq) of 'Rojo Pasión' and 'Z506-7' and analysed by a Sequenom Platform. 'Bergeron' and 'Currot' covered a genome extension of 394.9 and 414.3 cM, while 'Goldrich' and 'Currot' covered 353.5 and 422.3 cM, respectively. In these linkage maps important QTLs related to these phenological and fruit quality traits were identified. The most significant QTLs were localized in LG4 for ripening time, fruit development period and soluble solids content, and in the LG3 for skin and flesh colour. In LG4 and LG3 we can highlight the presence of NAC and MYB genes previously related to ripening time and fruit skin colour by other authors.