Ripening Mutants - Fruit Ripening: Physiology, Signalling and Genomics - page 261

gene-silencing approaches, TILLING cur-
rently would be the method of choice for
functional analysis of ripening-related genes
and could be applied to a range of fl eshy
fruit-bearing species. The attractiveness of
TILLING lies in the potential to generate an
allelic series of mutants in a gene of interest,
enabling a range of substitution alleles to be
recovered and their effects on the
phenotype established. However, in general,
current population sizes and mutagenesis
rates are insuffi cient to generate on average
more than one or two mutant alleles per
gene in tomato and melon. Therefore,
additional efforts will be needed to increase
population sizes to increase the likelihood
of recovering multiple alleles and for the
TILLING platforms to become more widely
accessible.

This review has focused on research
using tomato as a model system, where it is
comparatively easier than in other fl eshy
fruit-bearing species to identify the
underlying genes responsible for mutant
phenotypes. However, as advances in next-
generation sequencing technology continue
to progress, it will be possible to directly
sequence multiple cultivars or individuals
from populations that have altered
ripening behaviours. Such approaches will
allow natural allelic variation in ripening
and other fruit quality traits to be explored
in a range of fruit crop species, thereby
uncovering more subtle phenotypes
associated with ripening genes, including
those that could be directly incorporated
into elite breeding germplasm to facilitate
crop improvement.

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