Agriculture Reference
In-Depth Information
genetic grapevine research will likely combine
both SNP and SSR assessments. Lijavetszky,
Cabezas, Ibanez, Rodriguez, and Martinez-
Zapater (2007) found that SNPs provide a lower
probability identity than microsatellites, so
higher numbers of markers are needed to
generate similar probability values. The advan-
tage of SNPs is they are easier to work with
than SSRs.
Chloroplast microsatellite studies are of par-
ticular interest, since the genetic material of
chloroplasts (small chlorophyll-containing
organelles that are the photosynthetic units of
plants) is transmitted from mother to daughter
without undergoing any variation. As a result of
its perceived conservative rate of propagation,
chloroplast DNA has proven extremely useful
in plant population biology studies examining
the migratory routes of species, as shown by
Weising and Gardner (1999) and Avise (2000).
Chloroplast-specifi c haplotypes, or chlorotypes,
have been found in indigenous germplasm
believed to be typical of the specifi c region. For
chloroplast SSR analysis, as many as nine poly-
morphic chloroplast microsatellite loci have
been used, such as cpSSR3, cpSSR5, and
cpSSR10 (Arroyo-Garcia, Ruiz-García, Bolling,
Ocete, López, Arnold, et al. 2006; Imazio,
Labra, Grassi, Scienza, and Failla 2006).
Enantio. These pairs of cultivars are unrelated,
and provide an example of how incorrect
ampelographic identifi cations can nullify prop-
erly conducted genetic testing—and of course,
the converse is also true. Accurately labeled
vine samples in reference collections all over
the world are a must, because genetic testing
via microsatellite analysis can only confi rm or
rebuke the ampelographic identifi cation pro-
posed. Nowadays, better nurseries test new
acquisitions, and offer to have the DNA of
planting material of newer varieties tested, an
increasingly interesting resource.
This rigor is necessary. Since genetic analy-
sis is performed on vineyard collection grape-
vine samples (from a university or another
source) that were originally identifi ed by an
ampelographer (and how experienced an
ampelographer is anybody's guess) or by the
farmer who originally planted it, subsequent
genetic testing is at the mercy of that original
identifi cation. If grapevine samples are mis-
identifi ed and mislabeled in varietal collec-
tions, then genetic test results will be hope-
lessly wrong and of no use. In the California
Refosco
example, a mistake was easy to make
since the
Refosco
s and Mondeuse Noire resem-
ble each other. The university collection sample
had been identifi ed ampelographically as a
“Refosco” and when it was later found that its
DNA matched that of Mondeuse Noire, it was
logical to conclude that Mondeuse Noire and
Refosco
were one and the same. However, when
DNA tests were performed on authentic
Refosco
varieties in Italy, the DNA of which is nothing
like that of Mondeuse Noire, it became appar-
ent that the California grapevine had been
misidentifi ed ampelographically, and had in
fact been Mondeuse Noire all along. This exam-
ple clearly demonstrates why tested, accurate
ampelographic collections are a must. What's
more, to refer to a generic “Refosco” is also
incorrect: since there are at least four different
Refosco
s known, one needs to specify clearly
which
Refosco
is being studied, for example,
Refosco del Peduncolo Rosso or Refosco Nos-
trano. Clearly, Mondeuse Noire could not have
HITS AND MISSES OF AMPELOLOGY
Through the combined efforts of the above
methodologies, we have apparently been able to
correctly identify many erroneously named cul-
tivars. Examples include Pignoletto, which was
proven identical to Grechetto di Todi (Filip-
petti, Intrieri, Silvestroni, and Thomas 1999),
and Bonarda in Argentina, shown to be identi-
cal to Corbeau (known as Charbono in Califor-
nia) (Martínez, Cavagnaro, Boursiquot, and
Aguero 2008). However, unless ampelographic
and genetic studies are performed with utmost
care, wrong attributions are common: well-
known mistakes made in the past include mis-
identifying California
Refosco
as Mondeuse
Noire, Cilegiolo as Aglianicone, and Casetta as
