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4. GENETIC DIVERSITY...
than with ecotypes of their parent species while justifying from enzymes, RAPDs and ISJs.
On opposite, L. perenne cultivars remained to be the most similar to L. perenne ecotypes.
Cluster analysis and multidimensional scaling based on genetic similarities showed
clearly the ability of the majority of marker systems used to discriminate all populations
(Figure 4.8-4.15). The only exception was chloroplast DNA in L. multiflorum which
enabled to identify two groups with the same cpDNA haplotype in all populations within
a group (Figure 4.9A). These difficulties in separation of populations were also demonstrated
in the multidimensional scaling scatterplot. The distinct points were formed only by
four L. perenne populations (Figure 4.9B). In the case of the majority of marker system
used, neither dendrograms nor scatterplots separated populations in accordance to their
taxonomic position. In general, ecotypes of L. multiflorum tended to group together with
L. perenne while cultivars of this species formed a distinct cluster. The highest resolution
was obtained by insertional polymorphism. In the UPGMA dendrograms two clusters
could be identified, the first with all populations of L. multiflorum but Barball, and the
second with L. perenne populations and Barball (Figure 4.13-4.15). The multidimensional
scaling emphasised the difference between Italian and perennial ryegrass populations
in the case of Tpo1 and Lolcopia1. On opposite, all populations were scattered through
the whole space in the Lolcopia2 plot irrespectively of the rotation applied (Figure 4.15B).
Even the lower discrimination between species was obtained by RAPDs and ISJs. The
grouping based on RAPDs (Figure 4.11A) generated a separate cluster of the three
L. multiflorum ecotypes (Barball, Guliamo, Variamo), L. perenne cultivar (Lisuna) and
L. perenne ecotype from the Tatras. This then merged with L. perenne ecotypes from
Scandinavia (NGB4264, NGB10809). A strong overlap was also obtained when a multidimensional
scaling was applied (Figure 4.11B). When the dendrogram was plotted based
on ISJs two larger clusters can be observed, both with accessions of L. multiflorum and
L. perenne (Figure 4.12). Similarly, enzymes grouped all populations into two clusters with
accessions from both species in each cluster although the majority of L. multiflorum populations
formed a minor separate cluster (Figure 4.8). However this is not so obvious in the
scatterplot. Interestingly, L. hybridum was rather clustered with L. perenne. The data from organelle
DNA contrasted with the other marker system in that the majority of populations were
continuously distributed in the UPGMA dendrograms and scatterplots (Figure 4.9-4.10).