Schriften zu Genetischen Ressourcen - Genres

Necessity of development of systematics of cultivated plants
T. SMEKALOVA
VAVILOV was one of the first to declare the necessity of complex investigations of
species. However, the possibilities of systematics of cultivated plants have increased
considerably since that time. Along with classical morphological, anatomical, and
biological methods, new methods such as electron microscopy, biochemistry, and
genetics, are now at the disposal researchers. These allow elaboration of controversial
items in systematics in more detail. The enlargement of capabilities for use of
original materials in breeding programmes for different crops brings with it the necessity
of further development of systematics to a new, up-to-date level, including the
use of recent achievements in several fields of biological sciences.
On the other hand, the creation of a network of national and international genebanks
demands special, stringent requirements for the correct systematisation (classification
and nomenclature) of the material kept, and for the observation of the international
nomenclature rules. Practical experience shows that neglecting these rules will
inevitably lead to errors, which result in loss of material. For example, some American
genebanks, when accessioning germplasm, use only the genus and species
names together with a system of “descriptors”, which represents characters by coding
them as numerical symbols (scores):
A – Seed colour: (white – 0; red – 1; yellow – 2; etc).
B – Seed shape: (oval – 0; oblong – 1; round – 2; etc).
D – Leaf hairiness: (yes – 0; no – 1; etc).
The nomenclatural combination is often reduced to the Latin name of the genus, for
example, oats – Avena spp.
An obvious imperfection of this registration system lies in the danger of merely mechanical
mixing-up of figures, and in this case, any error is difficult to recognise immediately,
and one error would lead to others. We can see an example of this kind of
mistake on the cover of the “Report of a Working Group on Avena” (MAGGIONI et al.
1998), which shows a picture of an accession named ‘Creole’ (France) with yellow
seeds, but actually this variety has black seeds. Furthermore, if a genebank curator
is not very experienced, he may have difficulties with the coding of a character (e.g.,
oval vs. elongate; oval vs. roundish, etc.).
Taxonomic disagreements are a great obstacle for the work of both genebanks and
the systematics of cultivated plants as a whole. The underlying reason for such disagreements
are different views on the circumscription, structure and criteria of species
and intraspecific taxa. As MAYR (1973) noted, “In taxonomy we have almost unlimited
differences of opinions on different problems”. Thus, different experts have
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