Climacteric and Non-climacteric Ripening - Fruit Ripening: Physiology, Signalling and Genomics - page 3

Climacteric peak

Firmness

Yellow
or red

Climacteric fruit

Hard

CO 2

Ethylene

Green Soft

Coloration

Firmness

Yellow
or red

Non-climacteric fruit

Hard

Coloration

CO 2

Ethylene

Green Soft

Days after anthesis

Maturation

Fig. 1.1. Typical ripening pattern in climacteric and non-climacteric fruits.

demonstrated in the Charentais melon
variety ( Cucumis melo cv. reticulatus F1
Alpha), in which the ripening process from
the pre-ripe to over-ripe stages occurs
within 24-48 h (Rose et al. , 1998). In
accordance with these dramatic changes,
the expression of numerous ripening-
related genes, including those involved in
cell-wall breakdown and carotenoid bio-
synthesis, is induced and increased at the
transcriptional and translational levels at
the onset of ripening (Picton et al. , 1993;
Gray et al. , 1994; Fei et al. , 2004).
Exposure to exogenous ethylene can
also induce a rapid increase in auto-
catalytic ethylene production in climac-
teric fruits, even at the pre-climacteric

stage, thereby accelerating the ripening
process. In contrast, treatment with
inhibitors of the action of ethylene can
suppress and delay fruit maturation
(Blankenship and Dole, 2003; Watkins,
2006, 2008). Similar results have been
shown in a number of transgenic tomatoes
in which ethylene production was reduced
by the antisense-induced repression of the
1-aminocyclopropane-1-carboxylic acid
(ACC) synthase (ACS) and ACC oxidase
(ACO) genes, which encode ethylene bio-
synthesis enzymes; in addition, ethylene
sensitivity was reduced by the modifi -
cation of ethylene receptor genes
(Hamilton et al. , 1990; Oeller et al. , 1991;
Picton et al. , 1993; Wilkinson et al. , 1995).