Identification of quantitative trait loci for growth-related traits in the blood clam(Tegillarca granosa)OA

The blood clam(Tegillarca granosa)is an economically important marine shellfish in the southeast coastal area of China.In T.granosa breeding practice,growth-related traits are most important phenotypic selection index.In order to increase the breeding efficiency,we used a previously published genetic linkage map of T.granosa to map quantitative trait loci(QTL)for growth-related traits in a single full sibling F1 family.Eight growth-related traits including shell length(SL),shell height(SH),shell width(SW),shell weight(Swi),shell umbo width(SUW),as well as outer ligament length(OLL),meat weight(MW)and total weight(TW)of T.granosa were measured for QTL mapping.The estimated phenotypic correlations between any 2 of the 8 growth-related traits were significant(P<0.001).Twenty-nine QTL were identified for growth-related traits,including 13 QTL with the phenotypic variance of 4.20-15.63%in the female map and 16 QTL of 3.99%-14.58%in the male map.Thirteen amplification fragment length polymorphism(AFLP)markers were validated to closely link to seven QTL except the shell height.This is the first report of QTL mapping on growth-related traits in T.granosa.These QTL and their tightly linked markers present the initial step towards the goal of marker-assisted selection in T.granosa.