| Hyriopsis cumingii is the most important freshwater pearl mussel in China. Quality of freshwater non-nucleated was irregularity. Selectively strain with excellent performance of the pearl production of H. cumingii is an effective method for realizing the freshwater pearl mussel breeding of sustainable development. Estimated genetic parameters and genotype by environment interactions were selective breeding element task. In this paper, estimates of heritability and genotype by environment interaction of quality of pearl in H. cumingii, and correlation analysis of non-nucleated pearl quality parameters with growth traits and inner shell color of H. cumingii, and estimates of heritability and genotype by environment interaction of growth traits and inner shell color in the purple freshwater pearl mussel H. cumingii in operation stage, in order to provide theoretical and practical basis for the selective breeding with improving pearl quality. Mainly included the following contents:1 Estimates of heritability and genotype by environment interaction of quality parameters of non-nucleated pearl in the freshwater pearl mussel H. cumingiiGenetic parameters and genotype by environment interactions were estimated for non-nucleated pearl quality traits of H. cumingii, originating from twelve families with purple strain F5 and ten families with control population, reared at three commercial grow-out locations(Jinhua, Wuhu, Wujiang). At 18 th month, five pearl traits that are together the major determinants of pearl value(color, size, roundness, luster and pearl yield) were recorded. 38,380 pearls were harvest from the 1,697 host mussels in the three sites. Pearls produced at the Wuhu site were purple pearl percent bigger and more valuable compared to pearl produced at the Jinhua and Wujiang. Heritability estimates for purple(0.61 ± 0.25), pink(0.40 ± 0.12), yellow(1.08 ± 0.25), white(0.34 ± 0.09), size(0.42 ± 0.24), roundness(0.42 ± 0.24), luster(0.30 ± 0.22) and pearl yield(0.42 ± 0.23) were high. Donor related heritability estimates for purple(0.46 ± 0.02), pink(0.36 ± 0.12), yellow(1.06 ± 0.25), white(0.21 ± 0.08) were medium, host and donor by host interaction related heritability for it were low. Donor by host related heritability estimates for size(0.18 ± 0.24) and roundness(0.19 ± 0.24) were medium, donor and host related heritability for it were low. Host related heritability estimates for luster(0.15 ± 0.06) and pearl yield(0.37 ± 0.12) were moderate, donor and donor by host related heritability for it were low. Donor related genotype by environment interactions were no significant for purple, pink, yellow and white pearl. Genotype by environment interaction was present for size, roundness, luster and pearl yield due to re-ranking of relative family performances at the three sites. So, pearl color was controlled by the donor mussels, size and roundness were controlled by the host and donor interaction, luster and pearl yield were controlled by the host mussels. Given the complex relationship amongst pearl quality traits and the likelihood for G×E interaction effects care should be executed when designing breeding objectives for the genetic improvement of these traits in H. cumingii.2 Correlation analysis of non-nucleated pearl quality parameters with growth traits and inner shell color of H. cumingiiIn order to study the effect of donor and host mussels on the quality of non-nucleated pearls in freshwater pearl mussel. The purple strain F5 of H. cumingii was chosen as materials. Before grafting the saibos into mantles, the growth traits(shell length, shell height, shell width and body weight) of donor and host mussels were respectively recorded, and the inner shell color parameters including L、a、b、d E of donor mussels were measured. At the 18 th month after grafting, the specific growth rate and inner shell color of the host mussels were measured. Besides, the color, size, roundness, luster and weight of pearls were noted. The results showed that there was no significant correlation with the growth traits of the donor mussels and the non-nucleated pearl quality(P > 0.05), and that extremely significant correlation existed between inner shell color of the donor and pearls color(P < 0.01). Moreover, the greater the d E value of the donor mussels is, the higher percent of purple pearl the mussel can produce, whereas, a higher percent of white pearl was yielded when d E value of the donor mussels turns out to be lower. Specific growth rate of the host mussels had highly significantly positive correlation with the pearl size, luster and pearl yield(P < 0.01). The degree of correlation: body weight > shell length > shell width > shell height. Specific growth rate of the host mussels is remarkably correlated with pearl round(P < 0.01). The degree of correlation: shell length > body weight > shell width > shell height. No significant correlation between the inner shell color of the host mussels and the non-nucleated pearl quality was discovered(P > 0.05). In consideration the all the correlations above, it can be concluded that the pearl color is probably improved by improving the inner shell color of the donor mussels, and that non-nucleated pearl quality(size, luster, roundness, pearl yield) can be greatly enhanced by promoting growth traits of the host mussels.3 Estimates of heritability and genotype by environment interaction of growth traits and inner shell color in the purple freshwater pearl mussel H. cumingiiGenetic parameters and genotype by environment interactions were estimated from fifth generation purple strain H. cumingii reared at two sites(Chongming and Jinhua). Six shell growth traits and four inner shell color parameters were recorded in 1142 12-month-old individuals. Microsatellite-based DNA parentage analysis was used to assign the mussels to 13 paternal half-sib families and 37 full-sib families. Heritability estimates for shell length(0.20 ± 0.03), shell height(0.16 ± 0.06), shell width(0.17 ± 0.02), body weight(0.23 ± 0.01), and mantle weight(0.15 ± 0.06) were moderate, while that of shell weight(0.31 ± 0.03) was high. Estimates of the inner shell color parameters L, a, b, and d E heritability were 0.33 ± 0.19, 0.17 ± 0.10, 0.69 ± 0.17, and 0.33 ± 0.19, respectively. Purple selective strain of the fifth generation H. cumingii had high genetic diversity and expected heterozygosity was 0.791. Moderate or high heritability and high genetic diversity suggests that the fifth generation had a great selective breeding potential. All growth traits and color parameters, except for color parameter b, exhibited significant genotype by environment interactions at both sites. Considering growth and purple inner shell, it can be summarized that the 9 and 10 families are more preferable to culturing in Chongming, that the 20, 23, and 34 families are more appropriate to cultivating in Jinhua, and that the 21 and 22 families are suitable for both sites. Attention to the likely genotype by environment interaction affects in future purple H. cumingii selective breeding programs and culture practices. |
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