Agriculture Reference
In-Depth Information
4
Bintje
Piccolo
PM
3
3
2
2
1
1
0
Raw icrowaved
teamed
Boiled
Baked
Fig. 18.5.
Baby potatoes from three cultivars were cooked as shown and chlorogenic acid measured by
HPLC. Raw potatoes were the control.
Another study showed baked potatoes had simi-
lar antiproliferative and pro-apoptotic properties
to fresh potatoes, whereas chipping caused a re-
duction in bioactives (Madiwale
et al
., 2012).
Magic Molly, in Texas, Florida, and four loca-
tions in Alaska, including in the Arctic Circle,
and found total phenolics varied by 28%.
Chlorogenic acid was twofold higher in the po-
tatoes grown in the Arctic Circle versus Florida.
Anthocyanins were higher in potatoes grown in
Alaska (6.3-7.3 mg g
-1
) than in Texas or Florida
(4.4 mg g
-1
). Petunidin-
3-
coum-rutinoside-
5
glucoside was the most abundant anthocyanin,
ranging from 4.9 mg g
-
1
in Alaska to 2.3 mg g
-
1
in Magic Molly in Texas. Over a tenfold diffe-
rence between locations occurred in the expression
of some phenylpropanoid genes, and sizeable
differences were present in both early and late
phenylpropanoid genes.
Environmental effects on
phenylpropanoids
Phenylpropanoid expression in plants is well
known to be influenced by environment (Dixon
and Paiva, 1995), which is not surprising given
that one of their primary roles is to allow the
plant to cope better with stresses, including
drought, disease, and photooxidative stress. Thus,
it is expected that tuber phenylpropanoid profiles
will vary by location and year, in addition to geno-
type. Anthocyanins were found to be higher in
potatoes grown at higher altitudes in Colorado
than in the same cultivars grown in Texas (Reyes
et al
., 2004; Reddivari
et al
., 2007a). Analysis of
the total antioxidants and total phenolics in the
same cultivars grown in nine different states
showed that environment had a significant effect,
but the majority of the variation was due to geno-
type (Nzaramba
et al
., 2013). An up to ~35% dif-
ference in total phenolics was observed among
the same
11
potato cultivars grown in Canada in
2008 and 2009, with a mean difference of 16%
(Hu
et al
., 2012). We grew the purple cultivar,
18.8 Carotenoids
Carotenoids are synthesized in plastids from iso-
prenoids and function to help plants resist
photo- and oxidative stress and influence scent
and flavor (Dellapenna and Pogson, 2006; Caz-
zonelli and Pogson, 2010). Phytoene biosyn-
thesis is a rate-limiting step in carotenogenesis,
and
PSY
(phytoene synthase) expression can be
induced by light, photoperiod, drought, and
temperature (Cazzonelli and Pogson, 2010).
PSY1
expression in tubers was correlated nega-
tively with carotenoids, which might indicate
