Schriften zu Genetischen Ressourcen - Genres

B. PICKERSGILL, M.I. CHACÓN SÁNCHEZ and D.G. DEBOUCK
rank of genus should no longer be named under the provisions of the International
Code of Botanical Nomenclature. It further states, in article 1, that at the level of species
or below, cultivated plants should be named in accordance with the Botanical
Code “if, and only insofar as, they are identifiable with botanical [i.e., wild] taxa in
those ranks.” Since a domesticated subspecies is, by definition, not identifiable with
any wild subspecies, use of ssp. vulgaris to distinguish domesticated from wild beans
seems to violate the intentions of the Cultivated Code. However the Cultivated Code
provides no alternative category for this purpose, leaving the vernacular phrases
“wild common bean” and “domesticated common bean” as the only solution. This aspect
of the Cultivated Code certainly seems to need either clarification or revision in
subsequent editions.
The independent domestications in Mesoamerica and South America could be represented
by the more lengthy vernacular phrases “Mesoamerican domesticated beans”
and “Andean domesticated beans”. However, this becomes very cumbersome when
extended to the independent domestications within Mesoamerica. The only formal
category available is that of cultivar-group, which we consider more appropriate for
the products of differentiation within the major lineages of domesticated beans.
Differentiation under human selection.
Human selection has developed striking but parallel ranges of seed types, growth
habits and ecological adaptations in Mesoamerican and Andean domesticated beans
(SINGH et al. 1991). SINGH et al. (1991) used the informal category “Race” for what
they regarded as distinct lineages among domesticated beans in each region. The
only category provided by the Cultivated Code is cultivar-group. Race Mesoamerica,
Race Durango, etc. would then become Mesoamerica Group, Durango Group, etc.
The Cultivated Code explicitly permits cultivars (and, presumably, landraces) to belong
to more than one cultivar-group simultaneously. Habit types would therefore appear
as Climbing Group, Bush Group, etc., and use types as Popping (or NuΖa)
Group, Snap Bean Group, Navy Group, etc. Insofar as the races of SINGH et al.
(1991) reflect evolutionary lineages, then once the race of an accession is known,
deductions and predictions can be made about its other features. For example, we
predict that beans belonging to any of the three Andean races will carry chloroplast
haplotype C, while beans belonging to Race Mesoamerica will probably carry haplotype
K. But cultivar-groups based on characters such as habit type or seed colour are
artificial constructs, designed for particular groups of users, and permit no prediction
about other characters of those cultivar-groups. For example, Dutch cultivars of snap
bean may carry phaseolin T, hence be of Andean origin, or phaseolin S, hence originate
from Mesoamerica (ZEVEN et al. 1999).
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