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5. ORIGIN OF SEEDLING...
5.4. DISCUSSION
Tests or markers that enable to distinguish between closely related species are extremely
helpful in breeding, especially if species are very difficult to classify solely on the
basis of their morphological characters. Such tests need to be fast, easy and inexpensive.
The present data provide an empirical example that seedling root fluorescence works fairly
well in the majority of populations and thus, has some power in applications such as seed
contamination assessment. As expected the level of fluorescence is high in L. multiflorum
and very low in L. perenne. However, the test is not exact and perennial ryegrass populations
with extremely high fluorescence are observed e.g., cultivar Aberoscar and Scandinavian
ecotype NGB5030 as well as nonfluorescent Italian ryegrass populations do exist (Floyd
and Barker 2002). Variation across generations, years and locations has been also noted
(Stuczynska and Stuczynska 1994). Unfortunately, the reasons of this variability have not
been well understood and therefore, fluorescence should not be used as infallible guides to
classification of questionable seeds. On the other hand, the debate about the test application
has come to a standstill presumably because the reason underlying fluorescence in
L. perenne has been misunderstood.
For any species specific test, compared genomes have to be diverse enough to create
distinct markers for each species. A noteworthy example of how genetic markers can distin-