A History of the Potato - The Potato: Botany, Production and Uses - page 5

exercised by English landowners, provided the
impetus to grow the potato as a sustenance crop.
For the Irish, the crop was not counted as tax-
able production of the English estates.
In 1843, potato late blight surfaced in the
USA and later in Belgium, leading to crop failure
on a scale rarely seen before. By 1845, crop fail-
ure and famine occurred in Ireland and con-
tinued for an additional year. The germ theory of
diseases had yet to be developed, and the cause
of late blight became a target of endless conjec-
ture of plant scientists of the day (Bourke, 1993).
The environment was usually attributed the lar-
gest share of the causation of disease.
The Irish Potato Famine was one of the
worst catastrophes of the 19th century. During
2 years of severe food shortage, it inspired one of
the first national debates in England over the role
of the state in coming to the aid of the suffering
masses. The Irish were seen as a population out
of harmony with its resources and needing ad-
justment by natural (albeit genocidal) processes.
Arguments against helping the Irish included
the notion they were lazy, and the potato, which
required little care and investment, was a lazy
race's food. It was argued in Parliament that
famine food aid would simply make the recipi-
ents indolent and unable to sustain themselves.
Additionally, the 1840s was a decade of public
discourse on religious principles. Emerging from
this discussion was a declaration that the famine
was a visitation from God. Arguments to the
contrary were raised, but largely ignored.
Malthus's discourse on controlling the
growth of populations (overpopulation being
the expected mechanism for natural selection
and evolution toward a fitter population) pro-
vided a basis for popular support for the idea that
competition for space and sustaining resources
occurred not only among species of the natural
world but also among humans (Malthus, 1798).
In this mode of thought, the fittest would sur-
vive, and the Irish were simply a casualty of nat-
ural laws of survival and extinction.

1845. This event has been presumed to mark
a clear separation of potato bloodlines. One of
the most successful potato varieties, persisting
for over 100 years, is Russet Burbank. Russet
Burbank remains the first variety in production
in the USA.
The origin of Russet Burbank begins with
the introduction of Rough Purple Chili from the
Panamanian Consulate by Reverend Chauncey
Goodrich in 1850 (Goodrich, 1863a,b). The
Reverend took open-pollinated berries from his
plants and produced Garnet Chili. Later, other
breeders produced Early Rose, which was the
genetic mother of Burbank.
In the late 19th century, Early Rose was
crossed extensively in nearly all potato breeding
programs around the world. It is unclear which
traits Early Rose contributed to its progeny to
make it a universal ancestor; however, breeders
listed disease resistance among the most import-
ant traits they were seeking to incorporate into
new varieties. Lou Sweet selected a russeted vari-
ant of the Burbank potato, leading to the modern-
day variety, Russet Burbank (Dreyer, 1993).
From breeding efforts, the Early Rose be-
came the founding ancestor of nearly all potato
germplasm in Europe. One would presume
Rough Purple Chili brought with it resistance
to late blight, yet little evidence of this exists.
Using the marker for T-type cytoplasm, Ames
and Spooner (2008) analyzed the DNA of herb-
arium specimens in Europe. They determined
Chilean germplasm was extant in Europe before
the Irish Potato Famine, and after the famine,
the Andean cytoplasm persisted for decades, but
eventually disappeared ( Fig. 1.3 ) .
Evidence from the cytoplasm of heirloom
potatoes in the Canary Islands and India indi-
cates a mixture of Chilean and Andean cyto-
plasm in modern potatoes (Spooner et al ., 2005;
Ríos et al ., 2007). The disappearance of Andigena
cytoplasm could have occurred due to selection
for long-day adaptation, or due to the nuclear
genome entering an irrevocable state of male
sterility when crossed with the T-type cytoplasm
of the Chilean germplasm (Vilaró et al ., 1989).
As a relic of post-famine breeding efforts,
Russet Burbank shows a distinct and repeatable
level of resistance, which is described more prop-
erly as less susceptibility (Inglis et al ., 1996). For
the mid-1800s, and in comparison to the sus-
ceptibility of germplasm under wide cultivation
at that period in history, Russet Burbank and its

1.2 Potato Late Blight and Selecting

for Disease Resistance

The potato late blight epidemic started in
North America and culminated in the complete
destruction of the potato crop in Ireland in