The effect of the number of RAPD fragments on the estimation of genetic distances has been studied on 10 genotypes (Vitis vinifera) using 320 primers. A total number of 1683 scorable bands was obtained but only polymorphic bands (932) were considered in this work. The variation of the genetic distances, in relation to an increasing number of bands, was evaluated through a bootstrap sampling procedure. The mean coefficient of variation (CV) of the genetic distances decreased as the number of bands increased. A CV of 10% was obtained with about 100–150 bands while a CV of 5% with a large number of bands (400–500 and over). To reduce the cost and the time of the analyses, primers with different levels of polymorphism were compared. Genetic distance matrices, based on different numbers of bands and primer polymorphism, were highly correlated with the genetic distance matrix of the whole data set when they were determined with a large number of RAPD fragments, either from high or low polymorphic primers. The effect of the number of bands on the estimation of genetic distances was evaluated also through the variation of the pattern of aggregation among genotypes (cluster analysis). Stable clusterings were detected when a large number of polymorphic bands (400 and over) was used. Some rearrangements of the genotypes in the dendrograms was observed as the number of bands decreased; below 100–150 bands the clusterings were completely rearranged.
The effect of the number of RAPD markers on the evaluation of genotypic distances in Vitis vinifera
Fanizza, G.;Resta, P.;Ferrara, G.
1999-01-01
Abstract
The effect of the number of RAPD fragments on the estimation of genetic distances has been studied on 10 genotypes (Vitis vinifera) using 320 primers. A total number of 1683 scorable bands was obtained but only polymorphic bands (932) were considered in this work. The variation of the genetic distances, in relation to an increasing number of bands, was evaluated through a bootstrap sampling procedure. The mean coefficient of variation (CV) of the genetic distances decreased as the number of bands increased. A CV of 10% was obtained with about 100–150 bands while a CV of 5% with a large number of bands (400–500 and over). To reduce the cost and the time of the analyses, primers with different levels of polymorphism were compared. Genetic distance matrices, based on different numbers of bands and primer polymorphism, were highly correlated with the genetic distance matrix of the whole data set when they were determined with a large number of RAPD fragments, either from high or low polymorphic primers. The effect of the number of bands on the estimation of genetic distances was evaluated also through the variation of the pattern of aggregation among genotypes (cluster analysis). Stable clusterings were detected when a large number of polymorphic bands (400 and over) was used. Some rearrangements of the genotypes in the dendrograms was observed as the number of bands decreased; below 100–150 bands the clusterings were completely rearranged.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
