Yuehuan Zhang

Analysis of the early heterosis for interspecific hybrids between Crassostrea hongkongensis and C. gigas

To improve the oyster phenotypic character,9 Crassostrea gigas families(HH11,HH12,HH13……HH33),9 C. hongkongensis families(GG11,GG12,GG13……GG33)and 45 interspecific hybrid families(C. hongkongensis♀ × C. gigas♂)(HG11,HG12,HG13……HG153)were established by the method of unbalanced nest design(one male to three female)in July 2010.Moreover,their early phenotypic character,heterosis potence and heterosis were examined under the identical conditions.These results show that the hybrid weakness of fertilization and hatching levels(hp-1)were observed among interspecific hybrid families due to the gametal incompatibility and individual variation.On the whole,the outbreeding depression of larvae growth was observed with the significant hybrid weakness(hp-1);the heterosis potence of larval survival ranged from-1 to 1,and survival advantage occurred without the remarkable level;the significantly metamorphic heterosis(hp1)was investigated during the planktonic stage.Cytology and molecular biology of interspecific hybridization were further researched on the base of numerous hybrids with genetic information.

Comparisons of growth and development of hybrid and backcrossing progenies between Crassostrea hongkongensis and Crassostrea ariakensis

Hybridization and backcrossing between Crassostrea hongkongensis and Crassostrea ariakensis were conducted in this study,and consequently,the experimental groups HH(C.hongkongensis),AA(C.ariakensis),HA(C.hongkongensis ♀×C.ariakensis ♂),AH(C.hongkongensis♂×C.ariakensis♀),HAHA(HA♀×HA♂),HHA(HH♀×HA♂),HAH(HA♀×HH♂),HAA(HA♀×AA♂),AHA(AH♀×AA♂)were produced using the method of diallel cross.The results showed that C.hongkongensis eggs can be fertilized by C.ariakensis sperm(47.33%±2.52%),but not vice versa.The fertilization can occur between HA and HH or AA.The fertilization rates of backcrossing groups were lower than those of inbred groups HH and AA.The hatching rates of the backcrossing between HA and AA were lower than those of the other groups,which were 20.33%±2.08%(AHA),55.67%±2.52%(HAA)respectively.The larval survival rate of the AHA and HAHA was 0;The survival of HA larvae was lower than HH and AA.The hybrid larvae grew faster than C.ariakensis larvae,but grew slower than C.hongkongensis.The survival rates of HA,HH,and AA juveniles were not significantly different(P0.05).The hybrid juveniles grew faster than C.hongkongensis larvae,but grew slower than C.ariakensis.In addition,the larval and juvenile growth of HHA and HA was not significantly different(P0.05).The larval survival rate was not significantly different in HHA and HA.The juvenile survival rate of HHA was lower than HA,but was higher than that of the other backcrossing groups.The results provide a basis for study on the hybridization and backcrossing between C.hongkongensis and C.ariakenis.