Non-coding chloroplast DNA for plant molecular systematics at the infrageneric level.

With primers constructed against highly conserved regions of tRNA genes (trnTUGU, trnLUAA and trnFGAA) in chloroplast DNA, we have amplified two different non-coding spacers and one intron from four species within the genus Echium L. (Boraginaceae) and from two confamilial outgroups. The trnTUGU-trnLUAA intergenic spacer contains a greater number of polymorphic sites than the trnLUAA intron or the trnLUAA-trnFGAA intergenic spacer. We analyzed a total of 11 kb of sequence data from this non-coding DNA. Total nucleotide divergence between Echium species is on the order of 1% for these regions, all of which possess infrageneric length polymorphisms. The latter two regions contain indels which occur only in the 14 Macaronesian Island endemic species of Echium studied and suggest that these may form a monophyletic group.