马氏珠母贝(Pinctada martensii)2个地理群体杂交子代的杂种优势和遗传变异

HETEROSIS AND GENETIC VARIATION OF HYBRIDS FROM TWO GEOGRAPHICAL POPULATIONS OF PEARL OYSTER, PINCTADA MARTENSII

采用马氏珠母贝的印度群体(II0)和三亚群体(SS0)的2×2双列式杂交获得了4组子代,II1(II0♀×II0♂)、IS1(II0♀×SS0♂)、SI1(SS0♀×II0♂)和SS1(SS0♀×SS0♂);分析表明,杂交组子代IS1和SI1在壳高、壳长、绞合线长、壳宽、壳重上都表现出杂种优势;IS1在壳宽指数上表现出杂种优势,而在总重和壳重指数上未表现杂种优势;SI1在总重和壳宽指数上表现出杂种优势,而在壳重指数上未表现杂种优势;SI1在壳高、壳长、绞合线长和壳重上的杂种优势较IS1高,差异极显著(P<0.01),而IS1在壳宽上的杂种优势较SI1高,差异极显著(P<0.01)。应用6个微卫星位点分析4个组合子代的平均FST值为0.357,表明4个组合子代间有较大的遗传差异和较高的分化水平;平均等位基因数依次为SI1(6.17)>IS1(6.00)>II1(5.00)>SS1(4.67),等位基因丰度依次为SI1(5.34)>IS1(5.04)>II1(4.47)>SS1(4.55),期望杂合度(He)依次为IS1(0.55)>SI1(0.54)>SS1(0.44)>II1(0.42),观察杂合度(Ho)依次为SI1(0.52)>IS1(0.46)>SS1(0.35)>II1(0.29),杂交子代的杂合度和遗传多样性高于自繁子代,杂交增加了杂交子代的杂合度和遗传多样性,杂种优势与杂合度和遗传多样性增加直接相关;综合考虑杂种优势与遗传变异的结果,确定三亚野生群体♀×印度养殖群体♂杂交组合作为"珍珠贝育种规划POBs"的主要育种方式。

A 2 × 2 complete diallel cross between two populations of pearl oyster, Pinctada martensii, from Indian （II0） and Chinese Sanya （SSo） was carried out and four groups of offspring, II1 （II0 ♀ × II0 ♂）, IS1 （II0 ♀× SS0♂）, SI1 （SS0 ♀ × II0♂）, and SS1 （SS0 ♀ × SS0 ♂）, were produced. Hybrid IS1 and SI1 showed heterosis in shell height （SH）, shell length （SL）, hinge length （HL）, shell width （SW）, and shell weight （SWT）. IS1 had heterosis in shell width index （SWI）, but not in total weight （TW） and shell weight index （SWTI）, while IS1 had heterosis in total weight and shell width index, but not in shell weight index. SIl exhibited significantly larger heterosis in SH, SL, HL, and TW than ISl （P〈0.01）, but significantly smaller in SW （P〈0.01）. Six selected microsatellite markers were used to analyze four lines of progeny. The results reveal that the FST was 0.375 and the average numbers of alleles were in the order of SI1（6.17） 〉 IS1（6.00） 〉 II1（5.00） 〉 SS1（4.67）; the average allelic richness per locus was SI1（5.34） 〉 IS1（5.04） 〉 II1（4.47） 〉 SS1（4.55）; the average expected heterozygosities （He） were IS1（0.55） 〉 SI1（0.54） 〉 SS1（0.44） 〉 II1（0.42）; and the observed heterozygosities （H0） were SI1（0.52） 〉 IS1（0.46） 〉 SS1（0.35） 〉 II1（0.29）, indicating that the cross increased heterozygosity and genetic diversity, and directly brought about heterosis. As a whole, the cross between female Sanya wild population and male Indian cultured population promised more potential for pearl oyster breeding scheme, or POBs.