The Inheritance Studies On Colors Of Plumage, Beak And Foot-web In Duck

Animal melanin phenotypes have been paid much attention, such as black hair of pig, black skin of chicken and other traits. Melanin phenotypes mainly include colorful plumage, beak and foot-web. Compared with plumage color, the studies on beak and foot-web color nearly have not been reported. Hence, in this study, a new family based on both cherry valley ducks, white and black line separated from our previous study was built firstly, and then some different cross combinations were designed to study the genetic law of the plumage, beak and foot-web color, providing theory basis for breeding new duck line with specific melanin phenotypes based on recombination of plumage, beak and foot-web color.The main results are shown as follows:1. The results of chi-squared test between melanin phenotypes and sex indicated that the inheritances of plumage(P=0.986), beak(P=0.932) and foot-web(P=0.432) color had no relations with duck sex.2. Plumage, beak and foot-web color were treated as only one phenotype to study the melanin synthesis, the results showed that the melanin synthesis was controlled by one autosome locus(C/c), and the genotype “C_” can synthesize melanin, leading to colorful plumage or beak(not yellow), foot-web(not yellow), while the genotype “cc” can not synthesize melanin, leading to white plumage, yellow beak and yellow foot-web.3. The chi-squared test of actual ratio and expected ratio among different beak color phenotypes of second generation from 3 phenotype cross combinations(3 genotype combinations) showed that beak color was controlled by 2 autosome loci(C/c,Mb/mb)and the allele “Mb” contributed to melanin deposition in beak, but the gene “mb” had an inhibitive effect. The interaction between “C” and “Mb” loci generated three beak colors: black beak of which genotype was “C_Mb_”, spotted beak of which genotype was “C_mb mb”, and yellow beak of which genotype was “cc__”.4. The chi-squared test of actual ratio and expected ratio among different foot-web color phenotypes of second generation from 6 phenotype cross combinations(9 genotype combinations) showed that foot-web color was controlled by 3 autosome loci(C/c,Mw/mw,Y/y)and the allele Mw for which C locus had a recessive epistasis effect contributes to melanin deposition in foot-web, but the gene Y contributed to lutein deposition in foot-web. The interaction among “C”, “Mw” and “Y” loci generated three foot-web color: black foot-web of which genotype was “C_MwMw_y” and “C_Mwmwyy”, spotted foot-web of which genotype was “C_MwMwYY” and “C_MwmwYy”, and yellow foot-web of which genotype was “C_MwmwYY”, “C_mwmw__ ”and “cc____”.5. The chi-squared test of actual ratio and expected ratio between different plumage color phenotypes of second generation from 6 phenotype cross combinations(7 genotype combinations) demonstrated our previous studies on plumage color of duck: beak color was controlled by 2 autosome loci(C/c,T/t)and the allele “C” contributed to melanin synthesis, but the gene “T” contributed to melanin deposition in plumage. The “C” locus had a recessive epistasis effect for “T” locus which had a dosage effect. The interaction between “C” and “Mb” loci generated three plumage color phenotype: black plumage of which genotype was “C_TT”, grey plumage of which genotype is “C_Tt”, and white plumage of which genotype was “C_tt,cc__”.6. The correlation of plumage, beak and foot-web color was studied by one cross combination with the most offspring. The results showed that the correlation coefficients between plumage and foot-web color, foot-web and beak color, plumage and beak color were 0.633, 0.257 and 0.193 respectively. Besides, the recombination value of “T” and “Mb”, “Mw” and “Mb” are 28.5cM, 2.6cM respectively which were obtained by analyzing the optimal gene combination.