Natural Diversity and Genetic Control of Fruit Sensory Quality - Fruit Ripening: Physiology, Signalling and Genomics - page 245

from genome sequences. These discoveries
will greatly facilitate breeding for im-
proved fruit quality. To date, tomato plants
have been transformed with many genes
whose function is more or less related to
fruit quality, leading to variations in fruit
quality profi les, but none of these studies
has been used in cultivar development
since the modifi cation of the poly-
galacturonase gene for the modifi cation of
fruit texture (Kramer and Redenbaugh,
1994). Consumer concern about genetically
modifi ed crops, particularly in Europe,
hampers the use of such plants and
highlights the need for natural variation.
With genome sequences available in
several species (tomato, peach, apple,
grape and melon), many additional can-
didate genes will be identifi ed. High-
throughput technologies of genomics,
proteomics and metabolomics enable the
simultaneous quantifi cation of the
products of these genes during develop-
ment (Fei et al. , 2004; Alba et al. , 2005;
Baxter et al. , 2005; Carrari et al. , 2006;
Faurobert et al. , 2007), in different plant
tissues (Lemaire-Chamley et al. , 2005) or in
different genotypes (Schauer et al. , 2006;
Prudent et al. , 2009; Zanor et al. , 2009).
These studies will provide necessary data
for hypothesis testing to rapidly elucidate

the genes underlying favourable QTLs or
mutations and subsequently incorporate
them into cultivars.
Thousands of SNPs are being discovered
thanks to the new sequencing technologies
that can be used for genome mapping,
MAS, and positional cloning. Once a target
gene has been characterized, it will be
important to fi nd new allelic variants
within the large germplasm collections. An
increased knowledge of gene function and
regulation, as well as the development of
more precise and effi cient marker-assisted
selection, will help to avoid introgression
of large segments and undesirable loci into
elite lines. Mutational and transgenic tools,
such as mutation libraries in a uniform
genetic background (Menda et al. , 2004),
and techniques to screen for genetic
lesions in specifi c genes (Comai and
Henikoff, 2006; Rothan and Causse, 2007)
will aid in the description of desirable
alleles. Thanks to a wealth of novel tools
and techniques, to its vast natural
polymorphism at intra- and interspecifi c
levels, and to consumer demands for
nutritious foods, tomato will retain its
status as a valuable model crop for fruit
development, but major progress is also
rapidly needed in other fruit crops for the
satisfaction of consumers.

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