Komulainen P, Brown GR, Mikkonen M, Karhu A, Garcia-Gil MR, O'Malley D, Lee B, Neale DB, Savolainen O
Comparing EST based genetic maps between Pinus sylvestris and Pinus taeda
Theoretical and Applied Genetics: 2003 107: 667-678
A genetic map of Pinus
sylvestris was constructed using ESTP (expressed sequence tag
polymorphism) markers and other gene-based markers, AFLP markers and
microsatellites. Part of the ESTP markers (40) were developed and
mapped earlier in Pinus taeda, and additional markers were generated
based on P. sylvestris sequences or sequences from other pine species.
The mapping in P. sylvestris was based on 94 F-1 progeny from a cross
between plus-tree parents E635C and E1101. AFLP framework maps for the
parent trees were first constructed. The ESTP and other gene
sequence-based markers were added to the framework maps, as well as
five published microsatellite loci. The separate maps were then
integrated with the aid of AFLPs segregating in both trees (dominant
segregation ratios 3:1) as well as gene markers and microsatellites
segregating in both parent trees (segregation ratios 1:1:1:1 or 1:2:1).
The integrated map consisted of 12 groups corresponding to the P. taeda
linkage groups, and additionally three and six smaller groups for E1101
and E635C, respectively. The number of framework AFLP markers in the
integrated map is altogether 194 and the number of gene markers 61. The
total length of the integrated map was 1,314 cM. The set of markers
developed for P. sylvestris was also added to existing maps of two P.
taeda pedigrees. Starting with a mapped marker from one pedigree in the
source species resulted in a mapped marker in a pedigree of the other
species in more than 40% of the cases, with about equal success in both
directions. The maps of the two species are largely colinear, even if
the species have diverged more than 70 MYA. Most cases of different
locations were probably due to problems in identifying the orthologous
members of gene families. These data provide a first ESTP-containing
map of P. sylvestris, which can also be used for comparing this species
to additional species mapped with the same markers.
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