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including decreases in respiratory activity,
anthocyanin synthesis and chlorophyll
degradation (Martínez et al. , 1994).
Additionally, GA treatment delays softening
in persimmon fruit (Ben-Arie et al. , 1996).
Historically, ethylene has been con-
sidered the most crucial factor for ripening
initiation and the ripening process, par-
ticularly in climacteric fruits. Even today,
this perception remains unchanged.
However, fruit ripening would not proceed
normally without the effect of other
phytohormones, such as ABA, BR, auxin
and GA. The evidence reviewed here
indicates that the ripening process is
regulated by the coordinated actions of
multiple phytohormones in a complex
relationship in both climacteric and non-
climacteric fruits.
et al. , 2009). Isolated alleles modifi ed
the function of this enzyme at the
transcriptional level by a DNA insertion in
the 5 c fl anking region or null mutation, or
at the activation level by a single-
nucleotide polymorphism in the coding
region. Wang et al. (2009) indicated that
the ethylene production level and shelf-life
in apple are determined by the com-
bination of allelotypes of MdACS1 and
MdACS3 .
In Chinese pear ( Pyrus bretschneideri ),
the alleles PbACS1A and PbACS1B caused
by a single-nucleotide polymorphism and
sequence insertion in the promoter region
were observed (Yamane et al. , 2007). The
homozygous PbACS1A and heterozygous
PbACS1B lines exhibited climacteric
characteristics, whereas the homozygous
PbACS1B line showed non-climacteric
characteristics. Based on restriction frag-
ment length polymorphism analysis in
Japanese pears, Itai et al. (1999) indicated
that the fruit cultivars that produce higher
levels of ethylene possess an additional
PPACS1 allele, those that produce
moderate levels of ethylene possess an
additional PPACS2 allele and non-
climacteric-type fruit did not have
additional versions of these alleles. The
involvement of the ACO allele in con-
trolling ethylene production levels was
demonstrated in melon fruit using re-
striction fragment length polymorphism
analysis: the A 0 allele was related to a high
level of ethylene production, whereas the
B 0 allele was related to a low level of
ethylene production (Zheng et al. , 2002).
Périn et al. (2002) generated a melon
with climacteric characteristics by crossing
a typical climacteric-type Charentais melon
( C. melo var. cantalupensis cv. Vedrantais)
with a non-climacteric melon, PI161375 ( C.
melo var. chinensis ). A genetic analysis
indicated that the climacteric character-
istics described by fruit abscission and
ethylene production were controlled by
two independent loci ( Al-3 and Al-4 ).
Similarly, a cross between the climacteric-
type Charentais and the non-climacteric-
type Honeydew ( C. melo var. inodorus )
melon led to the generation of a climacteric
1.5 Distinctions Between Climacteric
and Non-climacteric Ripening
The cumulative experimental evidence
published to date has obscured the dis-
tinctions between climacteric and non-
climacteric ripening. For example, there
are a number of species in which the fruits
of different varieties and cultivars exhibit
both climacteric and non-climacteric
behaviours (Barry and Giovannoni, 2007).
In particular, apple (Wang et al. , 2009),
Japanese pear (Downs et al. , 1991; Itai et
al. , 1999), Chinese pear (Yamane et al. ,
2007) and melon (Zheng and Wolff, 2000)
have numerous natural variations related
to ripening, ethylene production and shelf-
life.
The storage properties of apple fruit
( Malus domestica ) vary substantially
depending on the variety. Certain varieties
can be stored for up to a year under
optimal conditions, whereas others rapidly
deteriorate. This shelf-life characteristic is
closely related to the level of ethylene
production (Gussman et al. , 1993). Several
allelic forms of the MdACS1 and MdACS3
genes that encode the ripening-related
ACS, which is a limiting enzyme for the
production of ethylene, were identifi ed in
apple fruit (Sunako et al. , 1999; Wang
 
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