Construction of a genetic linkage map and identification of QTL associated with growth traits in Malus sieversii.

110 F(1) individuals of apple were obtained by crossing between a good quality cultivar'Red Fuji'ofMalus domestica and an accession'Hongrou Apple'ofMalus sieversi. Using Joinmap3.0, a molecular genetic linkage map of Malus sieversii was constructed by 175 SSR and 105 SRAP markers which were integrated into 17 linkage groups and spanned 1299.67cM in genome with an average distance of 4.6cM between the markers. By using interval mapping method,17 QTLs for eight growth traits of Malus sieversii were detected, including 2 QTLs for tree height on cl and c16, 2 QTLs for stem height on c7, 2 QTLs for stem thickness on c3, 2 QTLs for new shoot length on c15 and c16, 2 QTLs for new shoot diameter on c2, 3 QTLs for internode number on c1, c2 and c2, 2 QTLs for internode length on c 1 and c2, 2 QTLs for lenticel density on c17, respectively. The phenotypic variations explained by each QTL ranged from 10.15% to 41.66%, and their LOD values varied from 2.54 to 4.53, of which five QTLs were major effect genes (LOD≥3.5).