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Abstract To investigate the effectiveness of ayu (Plecoglossus altivelis) artificial gynogenesis by different inducing methods, in this paper, the development of ovum was triggered by inactivated ayu sperm, then cold shock, heat shock and hydrostatic pressure treatment were carried out to retain the second polar body, respectively. The genetic feature of the offspring was analyzed by simple sequence repeats (SSR) and sequence-related amplified polymorphism (SRAP). Our data suggested that the fertility rate, eyespot rate and hatching rate of clod shock group were (39.6±2.5)%, (25.3±3.5)% and (6.7±1.2)%, respectively. The fertility rate, eyespot rate and hatching rate of heat shock group were (61.0±2.0)%、(34.7±2.1)% and (11.0±2.0)%, respectively. And the fertility rate, eyespot rate and hatching rate of hydrostatic pressure group were (80.3±2.1)%、(66.3±1.5)% and (57.0±2.0)%, respectively. These data showed that hydrostatic pressure treatment was the optimum approach to induce ayu gynogenesis. And the hatching rate was significantly higher than that of cold shock and heat shock with P＜0.01. The survival rate of 15-day-old offspring of hydrostatic pressure group was (15.2±8.2)%, while that of clod shock group was less than 1% and no survival was found in heat shock group. The results of SSR suggested ayu gynogenesis could be induced by hydrostatic pressure treatment through retaining the second polar body. In tested gynogenesis offspring samples, 14 samples in 16 were detected without male-specific bands. The gynogenesis rate of offspring was 87.5%. In the locus of Pag-003, the pattern showed that the gynogenesis offspring was all homozygote. While, in the locus of Pag-051 and Pag-076, the pattern showed that the recombination rates were 28.6% and 93.3% respectively between centromere and SSR locus. The result of SRAP showed that 5 bands in the female parent and 4 bands in the male parent were amplified respectively including 4 female-specific bands and 3 male-specific bands by the K-group primers. In the offspring, The dominant and recessive ratio of the female-specific band a4 was 1∶1(P=1.000), and that of a1, a3 and a5 were the same with each other and approximately followed Mendel’s law (1.33∶1)(P=0.705). One band in the female parent and 8 bands in the male parent were amplified respectively including 7 male-special bands by the P-group primers. Male-parent specific bands were detected in No.7 and No.14 (12.5%), which implied the sperms, triggering the ovum development of No.7 and No.14, were incompletely inactivated. Comparing with SSR, SRAP could be directly used to analyze multi-locus genetic feature each time and provide more genetic information. Our data suggest that hydrostatic pressure treatment could be used to induce ayu artificial gynogenesis. The results are of enormous significance in theoretical direction and practical application for ayu selective breeding. Our data suggest that hydrostatic pressure treatment could be used to induce ayu artificial gynogenesis. The results are of enormous significance in theoretical direction and practical application for ayu selective breeding.
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Received: 11 April 2013
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