PHYLOGENETIC ANALYSIS IN THE FESTUCA-LOLIUM COMPLEX USING MOLECULAR MARKERS AND ITS RDNA

Molecular markers were used to investigate phylogenetic relationships among the eight species of ryegrass (Lolium) and 11 species of fescue (Festuca). RAPD and RFLP analyses were carried out on total bulked DNA from each population. Factorial analysis of a phenetic distance matri x yielded three major groups: (1) fine-leaved fescues, (2) broad-leave d fescues and (3) ryegrasses. Six non-coding regions of chloroplastic DNA were PCR-amplified, then digested by 20 restriction enzymes. Nucle ar rDNA sequences, including internal transcribed spacers (ITSs) were used to estimate the average proportion of nucleotide substitutions. T he correlation between substitution rate estimated from ITS sequences and that estimated from organelle DNA restriction sites was very high (0.94), and the corresponding UPGMA trees were very similar, with a sl ightly better resolution of the ITS tree in the Lolium genus. The time -scale inferred from substitution rates indicated that the period sinc e divergence of the broad-leaved fescues from the fine-leaved fescues was four times as long as that since divergence of the genus Lolium fr om the former. Among the broadleaved fescues, meadow fescue was closer to the Lolium group, while F. glaucescens and tall fescue were very c losely related. North-African fescues were clustered together and gian t fescue was the most differentiated species in this group. Our datase t was merged with ITS sequences recovered from the EMBL database, and the neighbor-joining method was used to draw a phylogenetic tree. In t his tree, the tribe Poeae was clearly monophyletic, and more closely r elated to the Aveneae than to the Triticeae or Bromoideae. The genus F estuca appeared somewhat artificial, since Vulpia myuros and Dactylis glomerata were placed between fine-leaved and broad-leaved fescues.