VALIDATION OF GROWTH-RELATED QTL FOR MARKER ASSISTED SELECTION IN TURBOT (Scophthalmus maximus)

SCIARA, A.A; RODRÍGUEZ-RAMILO, S.T.; HERMIDA, M.; FERNANDEZ, J.; BOUZA, C.; MARTINEZ, P.

Santiago de Compostela

Simposio; The International Symposium on Genetics in Aquaculture XII; 2015

Classical familiar breeding programs have improved growth rate in turbot. However, marker assisted selection may further increase growth rate, because it is possible to identify specific genomic regions explaining a significant proportion of the phenotypic variance of such trait. Moreover, marker assisted selection could provide a more efficient selection of genetic variants that, otherwise, could be lost in classical breeding programs. The implementation  of marker assisted selection requires markers tightly linked to the causal mutation(s). The  increase of turbot genomic resources during the last years has enabled the construction  of linkage maps of appropriate density to detect growth-related QTL. The objective of this  study was to validate previously detected molecular markers associated to growth related  traits in turbot. Eighteen full-sib families derived from breeding programs were genotyped  for 39 markers at 11 linkage groups to look for association to weight, length and Fulton?s condition factor. The results indicate that 25 markers out of the 39 analysed showed significant  association in at least one family and for at least one trait. In addition, all the considered  linkage groups comprised at least one marker with significant association. Twenty markers out of the 39 analysed jointly explained 47.5% of the phenotypic variance of weight; 18 markers explained up to 57.7% of the phenotypic variance for length; and only one marker  was associated with Fulton?s condition factor, explaining 1.2% of the phenotypic variance.  The explained phenotypic variance when considering allelic variants, instead of markers,  was higher (87.3% for weight, 89.1% for length, and 11.4% for Fulton?s condition factor). The  conclusion is that a set of markers and alleles highly associated with growth in turbot is now  available. In practical terms and due to the sparse distribution of growth-related QTL in turbot across the genome, several markers from different linkage groups should be used to  increase genetic gain in selection programs.