Plant Genome II Conference
Town & Country Conference Center, San Diego, CA, January, 1994.
PG-II: GENOMIC MAPPING OF AN INTER-RACIAL HYBRID BETWEEN CORSICAN AND
LANDES RACES OF MARITIME PINE (Pinus pinaster Ait.)
GENOMIC MAPPING OF AN INTER-RACIAL HYBRID BETWEEN CORSICAN AND
LANDES RACES OF MARITIME PINE (Pinus pinaster Ait.).
Plomion C. 1,2, Durel C.E. 1, O'Malley D.M. 2
1-institut National de la Recherche Agronomique, 33610 Cestas,
FRANCE; 2-Department of Forestry, North Carolina State
University, Raleigh, NC.
Two moderate density genomic maps were independently
constructed for one F1 individual of maritime pine (Pinus
pinaster Ait.) using RAPD markers scored on magagametophytes.
One map was constructed using 62 selfed seeds, and the other
using 62 open-pollinated (OP) seeds. The two maps were
constructed because we were concerned about distortion due to the
genetic load of recessive lethal and semilethal genes in
conifers. Using Macintosh MapMaker (version 2.0) with a lod
score of 4 and a recombination distance of 25 cM, analysis of
high confidence RAPD markers segregating 1:1 (P > 0.01) generated
286 markers in the self and 266 markers in the OP, that were
placed into 14 linkage groups. The two maps are similar in size
(1382 cM for the self and 1325 cM for the OP maps) and also for
the ordering of the 235 shared markers. The maps and markers
will be used for QTL mapping of height growth and phenological
traits at early stage in an F2 population of 400 self progenies.
This approach is an alternative to the 3-generation outbred
pedigree mapping strategy. Although RAPD markers are usually
dominant, heterozygotes, homozygotes and recombinants can be
determined by screening F2 progeny for markers of known gene
order. This mapping strategy should allow the QTLs to be more
precisely defined than using other strategies for trees (half-sib
or double pseudo-testcross). In addition the mode of gene action
can be characterized. The comparison of the two maps will
facilitate detection of recessive lethals, and is a means to
validate the genomic map. Results to date do not show any
evidence for strongly distorted markers in the self which have
the Mendelian ratio in the OP. The genomic information obtained
by mapping in self families could be helpful for tree breeders in
designing line breeding strategies.
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