Genetic mapping and DNA sequencing of the loblolly pine genome
1994
Neale, D.B. | Kinlaw, C.S. | Sewell, M.M. (USDA Forest Service, Albany and Placerville (USA). Pacific Southwest Research Station)
Genetic maps and sequencing genes in loblolly pine (Pinus taeda L.) are being constructed to gain a deeper understanding of the organization and evolution of pine genomes. Two genetic maps were constructed using restriction fragment length polymorphism (RFLP) markers using complementary DNA (cDNA) probes from loblolly pine. Three generation outbred pedigrees were used for segregation and linkage analysis. One map was used to identify five major quantitative trait loci controlling wood specific gravity. A large number of RFLP markers were positioned on both maps, thus it was possible to merge the two independent maps to form a consensus map. All (200+)cDNA probes used for mapping were partially sequenced. The DNA sequences were compared to databases which resulted in the gene identification of a large (greater than 30) proportion of the mapped RFLP markers. The most interesting result from our mapping and sequencing activities is the extraordinarily large gene families that were found in loblolly pine. Gene families that exist in just a few copies in angiosperms were found to have 10, 50, or even 100 copies in loblolly pine. The map positions of members of gene families suggests that gene amplification more likely occurred by a mechanism such as retrotransposition than by polyploidization. Our current focus is to use cDNA mapping, QTL mapping, and cDNA sequencing to identify the genes which determine wood properties in loblolly pine
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