RIBOSOMAL-RNA GENES IN THE GENUS PINUS .1.

Ribosomal gene structure in Pinus pinea, P. halepensis and P. nigra has been analyzed by means of Southern blot hybridization after DNA digestions with Eco RI, Bam HI and Sac I restriction enzymes. Phage cloning, plasmid subcloning and partial nucleotide sequencing of the Pinus pinea rDNA demonstrated that the intergenic spacer (IGS) and the first internal transcribed spacer (ITS1) are very much longer than in angiosperm species, while the second internal transcribed spacer (ITS2) is closely related to angiosperms: our estimates are of 23 kb approximately for IGS and 2.64 kb and 0.25 kb for the ITS1 and ITS2 respectively in the more highly represented ribosomal genes.