Plant Genome III Conference

MAPPING AND SEQUENCING OF THE PINE GENOME.

The genus Pinus is one of the largest and most important taxa of forest trees with one hundred or more species are found throughout the Northern Hemisphere. We have chosen loblolly pine (Pinus taeda L.) as a representative pine for genomic mapping and large-scale cDNA sequencing. Initially we mapped large numbers of anonymous cDNAs using RFLPs and three-generation outbred pedigrees (Devey et al. 1994 Theoret. Appl. Genet. 88:273-278; Groover et al. Genetics 1994, in press). From these maps we have been able to make preliminary assessments about; (1) the distribution of members of gene families, (2) differences in the rates of recombination between the male and female parent, and (3) the relative synteny of markers between two unrelated pedigrees. We have subsequently sequenced these mapped cDNAs. Forty-three percent of the cDNAs could be identified based on similarity to gene sequences found in DNA sequence databases. Many of the identified cDNAs encode genes for cellular metabolism and photosynthesis. We are expanding our efforts to include large numbers of cDNAs from specialized tissues. The sequenced and mapped cDNAs will then be added to our existing genetic maps. In parallel we have also been mapping quantitative trait loci for various traits including wood properties. Following this approach we will compare map positions of identified cDNAs with those of QTLs for important traits in an attempt to better understand the relationship between phenotype and genotype in pines.