Linkage analysis by genotyping of sibling populations: a genetic map for the potato cyst nematode constructed using a "pseudo-F2" mapping strategy.
A mapping strategy is described for the construction of a linkage map of a non-inbred species in which individual offspring genotypes are not amenable to marker analysis. After one extra generation of random mating, the segregating progeny was propagated, and bulked populations of offspring were analyzed. Although the resulting population structure is different from that of commonly used mapping populations, we show that the maximum likelihood formula for a normal F2 is applicable for the estimation of recombination. This "pseudo-F2" mapping strategy, in combination with the development of an AFLP assay for single cysts, facilitated the construction of a linkage map for the potato cyst nematode Globodera rostochiensis. Using 12 pre-selected AFLP primer combinations, a total of 66 segregating markers were identified, 62 of which were mapped to nine linkage groups. These 62 AFLP markers are randomly distributed and cover about 65% of the genome. An estimate of the physical size of the Globodera genome was obtained from comparisons of the number of AFLP fragments obtained with the values for Caenorhabditis elegans. The methodology presented here resulted in the first genomic map for a cyst nematode. The low value of the kilobase/centimorgan (kb/cM) ratio for the Globodera genome will facilitate map-based cloning of genes that mediate the interaction between the nematode and its host plant.
Rouppe van der Voort
J N
JN
Graduate School of Experimental Plant Sciences, Department of Nematology, Wageningen Agricultural University, The Netherlands.
van Eck
H J
HJ
van Zandvoort
P M
PM
Overmars
H
H
Helder
J
J
Bakker
J
J
D000818:Animals; D008040:Genetic Linkage; D005819:Genetic Markers; D016678:Genome; D005838:Genotype; D009348:Nematoda / Q000235:genetics*; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic; D011198:Solanum tuberosum / Q000469:parasitology*
D005819:Genetic Markers