人工选育池蝶蚌的生长及不同世代遗传分析

GROWTH AND GENETIC ANALYSIS ON THE SELECTED BREEDING HYRIOPSIS SCHLEGELI

对引进后的池蝶蚌原种及其选育后代的形态和生长进行了研究,并利用RAPD技术,对原种、F1代、F2代和F3代的遗传特征进行分析,以期了解选育的效果。结果表明,人工选育的池蝶蚌后代具有生长更快、育珠能力更强的发育趋势。经过选育后,F3代较F2代的生长速度更快,壳的厚度更大,更适合育珠。RAPD结果显示,10个随机引物可产生稳定的可重复的多态性扩增结果,共检测出45条扩增带,池蝶蚌四代间的遗传多样性相差不显著,遗传分化水平较低,表明池蝶蚌经人工选育后与生长相关的等位基因频率有较大提高,遗传性状趋于稳定。

Hyriopsis schlegeli was originally from BiWa Ko Lake in Japan which was introduced into China by Fuzhou Hongmen Reservoir Exploitation Corporation Company in 1997. Artificial propagation was achieved in the next year. With the expectation to gain high-blooded breed, Hyriopsis schlegeli had been selected for several generations. 43 individuals from 108 stock introduced directly from Japan was selected as parents and its offspring Ft generation was gained in 1998. 5000 individuals of Ft were selected as reserve parents every year based on the shell which characteristics were measured including the ratio of shell-length to shell-width and weight. F2 and F3 were also gotten in 2001 and 2004, respectively. The shape and the growth of Hyriopsis schlegeli and its descendants by artificial selected breeding had been researched. 600 individuals of each generation as sample in the three generations were investigated. The average ratio of shell-length to shell-width of the F2 was 4.21 ± 0.27 in one-year-old while decreased to 4.01 ± 0. 30 in the next year. Individuals which the ratio of shell-length to shell-width was lower than the average ratios were selected as parents. The selected effects showed advantages in the F3. The average ratio of shell-length to shell-width of F3 was 4.07 ± 0.27 in one-year-old while decreased to 3.72 ± 0. 18 in the next year. Results indicated that in the growth rate of shell-length, shell-width and weight, the 173 generation was the fastest among three generations during the culture period from 22 to 34 months. At 34 month, the average shell-length of each generation were （ 110.50 ± 6.21 ） mm, （ 113.93 ± 6.47） mm and （120.87 ±5.91） mm, respectively. The average shell-width of the F3 was （32.32 ±2.63） mm while F2 and Ft were （28.52 ± 2.31） mm and （27.61 ± 2.13） mm. The weight of F3 was （ 174.83 ± 30.87） g, while F2 and Ft were （ 145.53 ± 14.35） g and （127.84 ± 13.75） g separately. The weight of F3 generation was heavier than that of F2 and F1. The results indicated that the descendant by artificial selected breeding could have better capacity on growth and pearl performance. Random amplification polymorphic DNA （RAPD） technique was used to analysis the genetic characteristics and to evaluate the artificial selection effect among the four generations. 10 primers, with more stable and reproducible characteristics, were selected from 99 random primers in RAPD to evaluate the selection effect. 45 bands were amplified in all. In the four generations, there were 8, 5, 3 and 2 polymorphic fragments were detected from P, F1 , F2 and F3, respectively. Accordingly, the proportions of polymorphic loci were 21.0 %, 12.8 %, 7.8 % and 5.4 %. In each generation, all the individuals had the similar genetic characteristics. The results showed that the genetic diversity of the four generations is similar and the level of genetic differentiation in the homo-generation is lower. It indicated that the genetic characteristics of the Hyriopsis schlegeli tends to be stable and become pure strain after three generation artificial selected.