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genes between DefH9- and INO-
transformed plants, suggesting similar
effects of these promoters on gene expres-
sion (see Plate 11). This strongly supports
the hypothesis that the Arabidopsis
thaliana AtINO promoter induces ovule-
specifi c expression in tomato. Functional
analysis of the differently regulated genes
using MapMan software showed several
transcriptomic differences in pathways
involved in minor carbohydrate metab-
olism, DNA synthesis, transcription
factors, secondary metabolism and hor-
mones. Key differentially regulated genes
were also related to transport: a cation
exchanger, two sugar transporters and the
nitrate transporter NRT1-3. Important
transcriptional effects were observed in
ethylene- and indole-3-acetic acid (IAA)-
related pathways.
Possible interactions between auxin and
ethylene pathways (biosynthesis, metab-
olism and perception) are also of interest.
Ethylene-responsive element binding pro-
teins (EREBPs) are both transcriptional
activators and repressors (Fujimoto
et al.
,
2000), and represent an important gene
family involved in fruit qualitative aspects.
As some EREBPs induce ripening and
others are repressed, EREBPs may affect
fruit ripening using antagonistic
mechanisms (Fei
et al.
, 2004). Seedless
fruit is associated with a longer shelf-life
than seeded fruit because seeds produce
hormones that cause senescence.
Gene set enrichment analysis showed
that IAA-responsive genes were down-
regulated in all transgenic fruits compared
with seedless or seeded controls, implying
that IAA and RolB downregulate other
auxin-associated genes independently of
seeds. It is possible that these regulators
induce parthenocarpy in a similar way to
the normal downregulation of SlARF7
ovary transcripts after pollination in
tomato (
Solanum lycopersicum
) (de Jong
et
al.
, 2009).
For metabolomic analysis, the con-
centrations of >400 metabolites were
evaluated in transgenic and control fruits.
The large-scale data were compared to
identify differences and similarities among
transgenic seedless fruits and seeded
control fruits at the breaker stage. Few
metabolomic changes were induced by IAA
or RolB: principal component analyses
could not separate the transgenic and
control lines (Martinelli
et al.
, 2009). Thus,
these gene/promotor combinations could
induce parthenocarpy in tomato without
large changes to the transcriptome or
metabolome.
18.7 Functional Genomics to Study Fruit
Development and Ripening in
Olive
Olive (
Olea europaea
L.) is an evergreen
species commonly grown in the Mediter-
ranean basin. The oil extracted from the
fruit is a predominant component of the
'Mediterranean diet', which has docu-
mented heart- and cancer-protective
benefi ts. These derive from the lipid
composition and from biologically active
molecules that accumulate during olive
fruit development. The oil can reach up to
30% of the total fruit fresh weight at full
ripening and is highly present in the
mesocarp and at lower levels in seeds. Oil
increase reaches a plateau in pulp after
veraison. A marked triacylglycerol
accumulation in seed and pulp occurs
after endocarp lignifi cation, when about 40
mg of oil per fruit per week can be
synthesized. The fatty acid profi le of the
oil accumulating in the fruit is important
in relation to its nutritional properties.
The main fatty acid is oleic acid (C18:1),
which represents about 75% of total fatty
acids, followed by linoleic (C18:2),
palmitic (C16:0), stearic (C18:0) and
linolenic (C18:3) acids. It is known that
important metabolites accumulate during
olive fruit development. These are
chlorophylls, carotenoids, polyphenols,
sterols and terpenoids, all important from
an olive oil qualitative, technological and
nutritional perspective. Information
regarding the genetic regulation of these
metabolic processes in olive is still very
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