异源四倍体鲫鲤、三倍体湘云鲫和它们父母本线粒体DNA 12S rRNA基因遗传变异的分析

采用质粒克隆测序方法，获得了异源四倍体鲫鲤5个个体、异源四倍体鲫鲤雌核发育二倍体后代2个个体、三倍体湘云鲫2个个体及红鲫、湘江野鲤和日本白鲫各1个个体的线粒体DNA 12S rRNA基因的全序列。经对比发现，异源四倍体5个个体共享2种单元型，异源四倍体鲫鲤雌核发育二倍体后代2个个体、三倍体湘云鲫2个个体以及红鲫、湘江野鲤和日本白鲫各1个个体分别共享1种单元型。用MEGA 1.0 软件分析了它们的碱基组成和核苷酸序列差异，用邻接法构建系统进化树。它们间的序列同源性在95%~99%之间，异源四倍体鲫鲤、三倍体湘云鲫和它们母本（分别为红鲫和日本白鲫）之间的序列同源性大于异源四倍体鲫鲤、三倍体湘云鲫和它们父本（分别为湘江野鲤和异源四倍体鲫鲤）之间的序列同源性，结果表明：异源四倍体鲫鲤和三倍体湘云鲫在线粒体DNA 12S rRNA基因上具有母性遗传特征。本研究另一值得注意地方的是异源四倍体鲫鲤经过9代(F3-F11)繁殖后，在5个个体中发现了2种单元型，说明在四倍体基因库中存在遗传多样性，为四倍体基因库的繁殖、保护和种群复壮提供了一些有价值的信息。

The Analysis of Genetic Variability of mtDNA 12S rRNA Genes in the Allotetraploid, Triploid Crucian Carp and their Parents

The complete 12S rRNA genes from the five F (11) allotetraploids, two diploid gynogens, two triploid crucian carps, one red crucian carp, one xiangjiang common carp, and one Japanese crucian carp were successfully cloned and sequenced. Sequence compositions and variations were analyzed with MEGA 1.0 software. Five F (11) allotetraploids shared two haplotypes, and two diploid gynogens, two triploid crucian carps, one red crucian carp, one xiangjiang common carp, one Japanese crucian carp shared one haplotype, respectively. The similarities among red crucian carp, xiangjiang common carp, allotetraploid, diploid gynogen, Japanese crucian carp, and triploid crucian carp varied from 95% to 99%. The similarities between allotetraploid, triploid crucian carp and their female parents (red crucian carp and Japanese crucian carp, respectively) were higher than those between allotetraploid, triploid crucian carp and their male parents (xiangjiang common carp and allotetraploid, respectively). Such result indicated that mitochondrial 12S rRNA genes of the allotetraploid and triploid crucian carp were inherited maternally. A phylogenetic tree was reconstructed using the neighbor joining method of the MEGA package. It was noticeable that after nine generations from F 3 to F (11) hybrids, the five F (11) allotetraploids shared two haplotypes (AT-1 and AT-2), indicating the allotetraploid stock had the genetic diversity. The results provided some valuable information for the breeding, genetic conservation, and population rejuvenation of the tetraploid stock.