Marker-based estimation of coefficient of coancestry in rice
2003
Tabanao, D.A. | Sebastian, L.S. | Carpena, A.L. | Hernandez, J.E. | Gironella, A.I.N. | Bernardo, R.N.
The coefficient of coancestry was calculated using two methods based on DNA marker data. Microsatellite marker analysis of eight modern rice varieties and their 25 progenies resulted in a total of 559 alleles from 119 loci. Marker estimates were computed for all 528 pairwise genotype combinations using the nonrelatives (Nfij) and the tabular (Tfij) methods. The mean values of Nfij, Tfij and fij were 0.1502, 0.0452, and 0.0649, respectively. Tfij and Nfij deviated by greater-than or equal to 0.10 from fij in about the same number of genotype pairs, but Tfij correlated better to fij than did Nfij. The two marker estimates themselves were highly correlated ad deviated by greater-than or equal to 0.10 in only 44/258 genotype pairs. Also, the Tfij dendrogram agreed more closely with the fij dendrogram than did the Nfij dendrogram, but both Tfij and Nfij were about as equally suitable as fij to cluster analysis. The differences between pedigree and marker estimates were due to human selection and to the assumption that initial progenitors were unrelated. The highly significant correlation of the marker estimates to fij indicated their validity as measures of genetic relatedness, while their immunity to assumptions of the pedigree method and their appropriateness to classification implied their superiority. Tfij is more accurate to use when pedigree information and DNA profiles are complete, otherwise, Nfij is more meaningful to use.
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