Genetic Linkage Map Construction And QTL Analysis For Growth-related Traits In Yellow Catfish (Pelteobagrus Fulvidraco)

A segregating population including 100 progenies from the cross between wild ((?)) and breeding (♀) yellow catfish was obtained based on a pseudo-testcross mapping strategy. Genetic linkage maps of yellow catfish (Pelteobagrus fulvidraco) were constructed by using SSR,SRAP and TRAP markers. In addition, QTLs related to five growth traits were analyzed.Polymorphic markers segregated in one of the parents were amplified by using thirteen pairs of primers detected within totally fifty pairs of SSR primers, of which four markers derived from female parent, three markers derived from male parent and six markers from combined parents. All SSR markers segregated according to the expected Mendelian ratio.Eighty-nine markers were amplified by using 196 pairs of SRAP primers. The average amplify amount of marker was 1.3 by each pair of primer. Thirty-eight markers were detected in female parent and forty-six markers in male parent, meanwhile five markers from combined parents. Chi-square Test shows that eight and eleven markers appear segregation distortion in female and male parent respectively. Totally markers segregated according to the expected Mendelian ratio are 78.6% in all SRAP markers.Twenty-six markers were amplified by using 56 pairs of TRAP primers. The average amplify amount of marker was 1.2 by each pair of primer. Nine markers were detected in female parent and eight markers in male parent, meanwhile nine markers from combined parents. Chi-square Test shows that two and three markers appear segregation distortion in female and male parent respectively. Totally markers segregated according to the expected Mendelian ratio are 80.8% in all TRAP markers.These markers were used to construct genetic map of yellow catfish. Fifty-one markers were involved in female map. It was covering a total of 585.5 cM in length and included sixteen linkage groups, the length skip from 8.2 to 127.4 cM, the average amount of marker in single linkage group skip from 2 to 8. The longest average gap distance was 32.1 cM located in the sixth linkage group and the shortest average gap distance was 4.6 cM located in the 14th linkage group. The average gap distance was 16.3 cM in the whole female map. Fifty-six markers were involved in male map. It was covering a total of 752.3 cM in length and included fifteen linkage groups, the length skip from 3.0 to 205.2 cM, the average amount of marker in single linkage group skip from 1 to 11. The longest average gap distance was 28.8 cM located in the sixth linkage group and the shortest average gap distance is 5 cM located in the 14th linkage group. The average gap distance was 17.7 cM in the whole male map. Twenty markers were involved in combined map. It was covering a total of 231.3 cM in length and included five linkage groups, the length skip from 5.3 to 84.7cM, the average amount of marker in one linkage group skip from 2 to 6. The longest average gap distance was 20.3cM located in the fifth linkage group and the shortest average gap distance was 5.3 cM located in the first linkage group. The average gap distance was 13.8 cM in the whole combined map. The coverage scale was 52.6% and 58.7% on female and male map respectively.These maps were used to scan QTLs related to five growth traits of yellow catfish. One Head length QTL was identified in female map that located in LG7, LOD value is 3.2 and explains 13% of phenotypic variation. A Body width and a Body length QTL were identified in male map that all located in LG1, LOD value is 2.4 and 2.1 respectively, while explains 12% and 11% of phenotypic variation respectively. These QTL could be considered to apply in marker-assisted selection for growth-related traits breeding of yellow catfish.The construction of genetic linkage maps of yellow catfish and QTL sites related to growth traits will lay foundations for Marker-assisted selection breeding of yellow catfish. It will alter the genetic improvement of yellow catfish.