Antioxidants and Bioactive Compounds in Fruits - Fruit Ripening: Physiology, Signalling and Genomics - page 113

element was detected in 17 out of 21 of
these gene promoters. However, no such
elements were detected in the promoters of
GPP, superoxide dismutase (SOD), chloro-
plastic iron SOD and ascorbate peroxidase.
ABA-, gibberellin-, heat shock-, wounding-,
fungal elicitor- and endosperm-responsive
elements were also detected in the
promoters (Ioannidi et al. , 2009).
Thus, manipulation of the light-
signalling apparatus in plants might be
useful for manipulation of fruit phyto-
chemicals (Azari et al. , 2010). More
information on progress using this valuable
approach, accentuating the outcome of
genetic and transgenic modulation of light-
signalling elements on the functional
properties of fruit, can be found in other
chapters in this volume covering the
individual phytonutrients.
Temperature regulates bioactive com-
pound pools in different fruits through the
general effect on metabolism (Dorais et al. ,
2008). However, a recent study suggested
that low temperature induces the expres-
sion of genes implicated in anthocyanin
biosynthesis and regulation in a number of
tree fruits (Xie et al. , 2012). This was done
by moderation of a molecular mechanism
in which the central role was played by the
cold-induced bHLH transcription factor
gene MdbHLH3 , and the resultant
activation of genes participating in antho-
cyanin accumulation and fruit coloration in
apples ( Malus domestica ) (Xie et al. , 2012).
In terms of AsA, among all of the genes
participating in its biosynthesis, oxidation
and recycling, only the expression of GPP
was induced by low temperature (Ioannidi
et al. , 2009). The GPP gene is believed to
play an important role during tomato
ripening, and apparently the same gene
was also upregulated by wounding and
ethylene but suppressed by high tem-
perature. Generally, AsA accumulation is
negatively regulated by high and positively
by low temperature, a phenomenon
coinciding with the expression profi le of
GPP. On the other hand, anoxia for 48 h
provoked an increase in AsA content in
tomatoes upon transfer to air, an
observation

induction of all AsA biosynthetic genes
(Ioannidi et al. , 2009). This response could
be tightly connected with the generation of
ROS under the above stress conditions
(Pucciariello et al. , 2012).

7.5.4 Cold storage

Cold storage is a common practice to
extend market life and maintain the
perceived quality of horticultural com-
modities. However, the effect of this 'stress
condition' on the phytochemical profi le of
fl esh fruits and vegetables is largely
unexplored. Preliminary data indicate that
the pronounced loss of fruit-keeping
quality during apple ripening at room tem-
perature after prolonged low-temperature
storage coincided with decreased content
of bioactive compounds (V. Goulas and
G.A. Manganaris, unpublished data). This
was not the case for plum fruit, where no
signifi cant loss of bioactive compounds
and antioxidant capacity of cold-stored
plums for an extended period was noticed
(Diaz-Mula et al. , 2009).
In papaya, chilling temperatures (1°C)
negatively affected the content of major
carotenoids, except for E -carotene, but
preserved or increased the ferulic and
caffeic acid levels compared with fruit
held at room temperature (25°C) (Rivera-
Pastrana et al. , 2010).
The phytochemical dynamics of each
fruit commodity should also be considered
based on the effect of extended cold storage
with special reference to the incidence of
cold-storage disorders. Such symptoms
vary by commodity and there are few
research reports regarding the relationship,
if any, between chilling injury symptoms
and fruit phytochemical profi le.

7.5.5 Postharvest application of signalling
molecules

Application of methyl jasmonate and
benzothiadiazole, a synthetic functional
analogue of salicyclic acid, was found to corresponding with the