A Genetic Linkage Map of Longleaf Pine (Pinus palustris Mill.) Based on Random Amplified Polymorphic DNAs
Eight megagametophyte DNA samples from a single longleaf pine (Pinus palustris Mill.) tree were used to screen 576 oligonucleotide primers for random amplified polymorphic DNA (RAPD) fragments. Primers amplifying repeatable polymorphic fragments were further characterized within a sample of 72 megagametophytes from the same tree. Fragments segregating in a l:1, present-to-absent, ratio were classified as Mendelian markers and mapped using multipoint linkage analysis. The analysis revealed 16 linkage groups of at least three markers, ranging in size from 21.1 to 185.6 cM, and six linked pairs (5.5 to 23.0 cM) of markers. The 22 groups and pairs included 133 RAPD markers and covered approximately 1,635 cM of genetic map distance. Genome size estimates, based on the linkage data, ranged from 2,612 to 2,656 cM. Using a 30-cM map scale and including the 11 unlinked markers and the ends of the 16 linkage groups and six linked pairs, the set of RAPD markers accounts for approximately 2,265 cM, or 85% of the genome.