Pericarps of mature fruit were analyzed for their
metabolite contents (Table 2). Twenty-one of the
major water-soluble metabolites were identified
and quantified by 1H-NMR spectroscopy. These
included 4 soluble sugars, 3 organic acids, 10 amino
acids and the glutamate (Glu) derivatives GABA and
pyroglutamate, choline and trigonelline, which all
have been previously identified in 1H-NMR spectra
(Mounet et al., 2007). The levels of soluble
carbohydrates were not significantly different in
fruit pericarp of control and HT plants. Together
with the similar fruit sizes, this result indicates that
the supply of carbohydrates was not affected by
the treatment. The levels of organic acids, mainly
citrate and malate, and of most amino acids were
also not significantly different between control and
treated plants. This was confirmed by performing a
principal component analysis of the data according
to Mounet et al. (2007). The first and second
components explained 82% and 12% of total
variability, respectively, but did not discriminate
between HT and control fruits (not shown). Mean
Glu levels were found to be lower in fruits from HT
plants (Table 2)