RIBOSOMAL-RNA GENES IN THE GENUS PINUS .1.

Ribosomal gene structure in Pinus pinea, P. halepensis and P. nigra ha s been analyzed by means of Southern blot hybridization after DNA dige stions with Eco RI, Bam HI and Sac I restriction enzymes. Phage clonin g, plasmid subcloning and partial nucleotide sequencing of the Pinus p inea rDNA demonstrated that the intergenic spacer (IGS) and the first internal transcribed spacer (ITS1) are very much longer than in angios perm species, while the second internal transcribed spacer (ITS2) is c losely related to angiosperms: our estimates are of 23 kb approximatel y for IGS and 2.64 kb and 0.25 kb for the ITS1 and ITS2 respectively i n the more highly represented ribosomal genes.