It has been proposed that 6x tall fescue evolved separately on the north and south sides of the Mediterranean Sea (Sleper, 1985; Borrill et al., 1971). This proposition is based on the different ecotypes from northern Europe and North Africa and an observed lack of interfertility between some North African and northern European tall fescue plants (Hunt and Sleper, 1981). These ecotypes have unique characteristics adaptive to the very different environmental conditions in those parts of the world. Those that predominate in northern Europe include the germplasm that has contributed significantly to most cultivated tall fescue cultivars, but there is much interest among breeders to tap the unique characteristics (e.g., excellent fall growth) of African tall fescue. However, intersterility between the ecotypes may make it difficult to introduce such traits into the cultivars that are popular in temperate regions.
In recent years, DNA sequence analysis and fungal endophyte surveys have reinforced the notion that northern and southern tall fescue ecotypes are very distinct. They also have helped identify the ranges of these tall fescue groups. The southern ecotypes range from North Africa to the Western Mediterranean, the Iberian Peninsula, and Italy and are bounded roughly at the Pyrenees and the Alps. The northern ecotypes extend from northern Europe into Iberia and, possibly, Morocco and Italy. Most 6x tall fescues south of the Pyrenees and the Alps and in North Africa harbor endophytes (designated FaTG-2 and FaTG-3) that are genetically, biochemically, and morphologically distinct from N. coenophialum (Christensen et al., 1993; Tsai et al., 1994; Clement et al., 2001), whereas N. coenophialum is found consistently in northern tall fescue and in those tall fescue lineages introduced from northern Europe into North America, Australia, and New Zealand. Our phylogenetic analysis of chloroplast DNA (cpDNA) sequences (Schardl et al., 2008; Craven and Schardl, unpublished data, 2002) also places the southern tall fescues well apart from northern tall fescues. In fact, the sequences from northern European tall fescue are more similar to those of Italian ryegrass (Lolium multiflorum Lam.) and meadow fescue (L. pratense) than to those of the southern tall fescue ecotypes. This is well in keeping with the long-standing observation that northern tall fescue can readily hybridize with ryegrasses and meadow fescue, but not with North African tall fescue. Clearly, these observations warrant further taxonomic revision of the hexaploids in subg. Schedonorus.
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