Agriculture Reference
In-Depth Information
S. tuberosum
, with eight cultivar groups: Ajanhui-
ri, Andigenum, Chaucha, Chilotanum, Curtilo-
bum, Juzepczukii, Phureja, and Stenotomum.
Arguments to use International Code of Nomen-
clature for Cultivated Plants (ICNCP) categories
rather than International Code of Botanical No-
menclature (ICBN) categories were discussed by
Spooner and Hetterscheid (2005), but Spooner
et al
. (2007b) classified the cultivated potatoes
again at the species level, with four species
(
S. ajanhuiri
,
S. juzepczukii
,
S. curtilobum
, and
S. tuberosum
). Within
S. tuberosum
, two cultivar
groups are recognized: Group Andigenum and
Group Chilotanum.
A very useful paper is that of Ovchinnikova
et al
. (2011), who compiled all the epithets asso-
ciated with the cultivated potato (many of which
have appeared only in the Russian literature)
and placed them in synonymy of the four species
names they accepted. They selected type speci-
mens (lectotypes) for as many of the validly pub-
lished names as possible, using—if available—
material cited by the original authors. They also
provided descriptions of the cultivated potato
species and cultivar groups, and a key, where the
“relatively modern varieties” within
S. tuberosum
were also included.
Spooner and collaborators on the Solanaceae
Source website made it unnecessary to establish
which species could be the actual progenitor of
the cultivated material. The complex has often
been found to be separated into a northern and a
southern group, and in phylogenetic studies the
cultivated material is usually associated with the
northern representatives of the complex, indi-
cating a Peruvian origin (Kardolus
et al
., 1998;
Spooner
et al
., 2005; Jacobs
et al
., 2008). The
AFLP data of Spooner
et al
. (2005) showed that
the cultivated potato material they investigated
grouped in one clade, nested within the clade of
the northern part of the
brevicaule
complex.
Since, in their view, that part of the
brevicaule
complex should be reduced to one species, they
consider the origin of the potato to be a single
domestication event. However, other studies
have pointed out that the presence of several
chloroplast haplotypes in the cultivated mater-
ial, many of which also occur in wild species,
suggest a number of successive domestication
events (Sukhotu
et al
., 2004; Sukhotu and
Hosaka, 2006). Hosaka (2003), also based on
chloroplast haplotypes, suggested that perhaps
other species, like
S. tarijense
, could have played
a role in the pedigree of the cultivated potato. In
any case, defining “single origin” as “derived
from one species” is not very informative about
the way the cultivated potato arose from the
brevicaule
complex, which would certainly have
involved multiple events and different progenitor
genotypes.
If the problem of the progenitor species
seems to be solved, there remain the questions as
to what constituted the first cultivated material
and how did our modern cultivated potato arise?
Hawkes (1990) presented the following account,
explaining the origin of the seven cultivated spe-
cies he recognized. The diploid
S. stenotomum
is
considered to be the most primitive cultigen, and
in its turn, the progenitor of all other cultivated
material, including the tetraploid
S. tuberosum
subsp.
andigenum
, the group of South American
landraces from which the modern cultivated potato,
S. tuberosum
subsp
. tuberosum
, was derived. Crosses
between
S. stenotomum
and
S. megistacrolobum
,
Solanum acaule
and
S. tuberosum
subsp
. andigenum
led to the diploid
S. ajanhuiri
and the triploids
S. juzepczukii
and
S. chaucha
, respectively. Crosses
between
S. juzepczukii
and
S. acaule
led to the
pentaploid
S. curtilobum
.
S. phureja
was derived
Problems/controversial issues
in the taxonomy of the potato
The taxonomic treatment of the South Ameri-
can landraces and their relationship to the wild
species has been the subject of many studies,
sometimes with contrasting results. We review
briefly controversies about the origin and further
development of the cultivated potato, whether
there is a single or multiple origin(s), the nature
of the material introduced into Europe before and
after the late blight epidemics of the 1840s, and
the modern views on how to subdivide the crop.
The origin and further development
of the cultivated potato
The situation about the origin of the cultivated
potato seems clear enough. Many studies have
pointed to the
brevicaule
complex as harboring
the closest relatives of the crop. Unfortunately,
the taxonomy of this complex was somewhat
confused, but the recent synonymy proposed by
