AN RFLP LINKAGE MAP FOR LOBLOLLY-PINE BASED ON A 3-GENERATION OUTBREDPEDIGREE

A genetic linkage map for loblolly pine (Pinus taeda L.) was construct ed using segregation data from a three-generation outbred pedigree con sisting of four grandparents, two parents, and 95 F-2 progeny. The map was based predominantly on restriction fragment length polymorphism ( RFLP) loci detected by cDNA probes. Sixty-five cDNA and three genomic DNA probes revealed 90 RFLP loci. Six polymorphic isozyme loci were al so scored. One-fourth (24%) of the cDNA probes detected more than 1 se gregating locus, an indication that multigene families are common in p ines. As many as six alleles were observed at a single segregating loc us among grandparents and it was not unusual for the progeny to segreg ate for three or four alleles per locus. Multipoint linkage analysis p laced 73 RFLP and 2 isozyme loci into 20 linkage groups; the remaining 17 RFLP and 4 isozyme loci were unlinked. The mapped RFLP probes prov ide a new set of codominant markers for genetic analyses in loblolly p ine.