Taxonomy - The Potato: Botany, Production and Uses - page 25

suggest an ultra bar-coding approach to exam-
ine variation below the species level systematic-
ally, assembling whole organellar genomes and
large (greater than 5 kb) contiguous portions of
the nuclear genome, and expanding the trad-
itional bar-coding regions to their full, many-
kilobase length, making it far more sensitive
than traditional DNA bar coding. So far, this has
not yet been applied to potato, and Spooner
(2009), looking at ordinary bar coding, even
claims that bar coding does not work in section
Petota and ascribed this to the complexity of the
group and not to the suspect nature of many wild
potato “species”. Bar coding aims at distinguish-
ing species, and in a group where the species sta-
tus of the entities that have been recognized is
debatable, the failure of bar coding does not reflect
on the approach but on the nature of the studied
group. Whether “ultra bar coding” might improve
the situation remains to be seen.
If, through the power of NGS, we could iden-
tify and characterize the genes actually coding for
the characters used in taxonomic classification
(e.g. leaf dissection, corolla shape), a high-resolution

phylogeny reconstruction could become possible,
with genes underlying key traits either agreeing
or disagreeing with the neutral markers usually
used for phylogeny reconstruction. Complete se-
quences will also be helpful to study synteny at
different levels; for example, giving information
on the sequences of the breakpoints involved in
chromosome segment rearrangements. Since
phenomena like inversions are rare events, they
can be phylogeny informative (Szinay et al ., 2012).
Undoubtedly, (next-generation) genome sequence
work can be instrumental for the development of
markers that might be useful to elucidate further
the phylogenetic relationships within section
Petota . Thus far, such new markers have not led to
new insights in the structure of this group of
Solanum species, and the availability of complete
genome sequences has not been exploited in other
ways for this purpose. Genome sequences are a
potential source of relevant comparisons, but so
far their use has been aimed mainly at plant breed-
ing strategies, like the isolation of disease-resistance
genes and the elucidation of tuberization (PGSC,
2011), rather than taxonomic applications.

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