pdf wkg Dav.14-14 - Davidsonia

Davidsonia 14:4
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traits being lost. It is imperative that this situation be remedied and that
there be a thorough and systematic examination of representative selections
from the remaining populations. The use of DNA genetic markers to
determine variability and relationship to important economic traits will
certainly be of value in this task (Daubeny, 2002; Finn and Knight, 2002).
While conservation of R. strigosus populations is important, there is recognition
that the species, along with two other Rubus species, R. spectablis Pursh.
and R. parviflorus Nutt., can be aggressive invaders of areas disturbed by
logging, burning, and site preparation activities and can impede reforestation
efforts by competing for nutrients, moisture, and light (Oleskevich et
al., 1996). It is obvious that there must be an appropriate balance between
conservation and eradication. It seems that it would be a relatively simple
matter to take representative plants from sites on which there is proposed
eradication.
The genetic base for modern day red raspberry breeding is being expanded
by the introduction of genes from the native North American red
raspberry. Efforts are also being made to introduce new genes from the
European red raspberry, the original genetic base, which is probably as narrow
as that of its North American counterpart (Jennings et al, 1991).
Already there has been some success with the introduction of genes from
related Rubus species into red raspberry breeding programmes (Daubeny,
2001). For example, the successful cultivar ‘Tulameen’ (Figure 18), released
from the PARC breeding programme in 1989, has genes from the black
raspberry, R. occidentalis L. (Daubeny and Kempler, 2003). These genes were
introduced into the red raspberry gene pool by the breeding programme at
the East Malling Research Station (now Horticulture Research International)
in the United Kingdom. It has taken four to six generations to recover
acceptable red raspberry qualities combined with black raspberry traits, such
as fruit firmness, extended shelf life and late ripening. In raspberry breeding,
a generation may be as long as seven to eight years, which means that the
original interspecific crosses were made in the 1950s. Other related species,
now appearing in the derivations of new cultivars, include R. spectabilis (Pacific
Coast salmonberry), R. arcticus L. (Arctic raspberry), R. odoratus L. (Eastern
North American purple flowering raspberry), and the Asiatic species, R.
coraneus Mig., R. cockburianus Hemsl., R. crataegifolius Bge. and R. phoenicolasius
Maxim. Each species has genes for useful plant traits, some of which are