Antioxidants and Bioactive Compounds in Fruits - Fruit Ripening: Physiology, Signalling and Genomics - page 116

increased yield and improved postharvest
characteristics (Dorais et al. , 2008). More
recently, breeding and biotechnological
programmes have had an increased
emphasis on increasing the accumulation
of: (i) carotenoids including lycopene and
xanthophylls in tomatoes (Tanaka and
Ohmiya, 2008; Farre et al. , 2011; Zhao and
Shewry, 2011); (ii) fl avonoids, proantho-
cyanidins and anthocyanins in tomatoes
(Willits et al. , 2005; Schijlen et al. , 2006;
Butelli et al. , 2008; Gonzali et al. , 2009;
Vogt, 2010), grape berries (Xie and Dixon,
2005; Ageorges et al. , 2006; Tanaka and
Ohmiya, 2008; Terrier et al. , 2009; Zhao
and Shewry, 2011) and other crops (Zhao
and Shewry, 2011); (iii) vitamin C in
different fruit crops (Davey et al. , 2006;
Lippman et al. , 2007; Stevens et al. , 2007;
Smirnoff, 2011; Bulley et al. , 2012); (iv)
folates (Almeida et al. , 2011; Hanson and
Gregory, 2011); (v) vitamin E (DellaPenna
and Mene-Safrane, 2011); and (vi) other
fruit bioactive molecules, like polyamines
(Mehta et al. , 2002; Nambeesan et al. ,
2010) and glucosinolates (Goldman, 2011).
However, in addition to increasing the
phytonutrient content in fruit, molecular
breeding projects need also to consider the
functionality and the bioavailability of the
individual components in humans in
combination with reducing the con-
centration of antinutritional compounds
such as phytic acid and calcium oxalate
(Goldman, 2011).

hybrids enriched with 'health-promoting
substances' is connected with the develop-
ment of molecular markers linked to
useful traits. It is also essential to exploit
all recourses and approaches as they
become available, including potential
systems/synthetic biology workfl ows
applied to the production of target bio-
active compounds in consumer-friendly
hosts such as fruit crops. The discovery
and use of tissue-specifi c promoters
known to control biosynthesis and
accumulation of bioactive compounds will
lead to the effi cient production of fruit and
vegetable varieties that possess enhanced
functional properties. The interplay
between genotype and environment can-
not be overlooked, so future investigations
to close this research gap may include the
following:

x Consideration of phytochemical char-
acteristics of new fruit cultivars in
addition to traditional breeding ob-
jectives of yield, market life and disease
tolerance. An emerging research area is
the investigation of phytochemical
profi les

of either traditional or

'forgotten' indigenous cultivars.
x Comparison of bioactive phytochemical
content of fruit crops with distinct
ripening profi les among their cultivars,
e.g. suppressed-climacteric and climac-
teric plums; melting, non-melting and
stony-hard peaches; European and
Japanese pears; citrus hybrids.
x Studies of the possible synergistic
effects among different classes of phyto-
chemicals during fruit ripening.
x Avoid general statements regarding
health-promoting properties of fruits.
Results need justifi cation, especially
with regard to actual bioavailability of
the phytochemicals within fruits.
x Detection, evaluation and interpretation
of fruit antioxidant capacity are advised
to be undertaken by more than one
method due to the complexity of the
different chemical compounds of the
fruit.

7.7 Conclusions and Perspectives

In order to fully exploit modern bio-
technological and/or molecular breeding
approaches, necessary prerequisites for
improving the nutritional and health-
promoting attributes of fruit include
knowledge of the biosynthetic pathways at
biochemical and molecular levels, as well
as the regulatory steps controlling the rate
of biosynthesis and the pool size of the
individual compounds. In our opinion, the
future for obtaining new cultivars and