Hybridization between “Haida No. 1” and Orange-shell line of the Pacific oyster reveals high heterosis in survival

Abstract

In order to assess the heterosis of the hybrid between the selected lines and develop a new hybrid variety of the Pacific oyster (Crassostrea gigas) with excellent survival and growth characteristics, a diallel crosses between selected “Haida No.1” (H, 12th generation) line and Orange-shell (O, 9th generation) line of C. gigas were carried out. Heterosis for growth and survival of two parental lines (HH, H♀ × H♂ and OO, O♀ × O♂) and their reciprocal hybrids (HO, H♀ × O♂ and OH, O♀ × H♂) were systematically assessed at both larval and grow-out stages. At larval stage, the two reciprocal hybrids exhibited heterosis in both survival and growth. Compared with HH, the survival rate of OH increased by nearly 23.00% at larval stage. Moreover, the heterosis in survival (average: 35.27%) was higher than that in growth (average: 8.03%) at larval stage. During grow-out phase, reciprocal hybrids showed excellent growth and survival traits at three commercial culturing areas. The high-parent heterosis for survival of hybrids at Rushan were higher than those at Rongcheng or Huangdao. Notably, the survival rate of OH increased by nearly 32.00% compared with HH at Rushan. Among three sites, the high-parent heterosis in survival varied from 31.18% to 141.18% at day 450. Overall, OH (Orange-shell line ♀ × “Haida No. 1” line ♂) exhibited superior growth and survival traits among four crosses, which could be prioritized as a new alternative variety for commercial oyster cultivation.