Ripening, ethylene action

The ripening of nonclimacteric fruits is usually considered as a process that as a whole does not require ethylene. Nevertheless, endogenous ethylene is involved at some steps of development of these fruits. In general, chlorophyll degradation in nonclimacteric fruits is believed to be ethylene stimulated, whereas the synthesis of pigments can depend on ethylene action or not. ... 

Previous publications reported that ethanol treatment retarded ripening of several fruits, including whole tomatoes and tomato slices (Saltveit and Mencarelli 1988). Also, ethanol can slow down tomato ripening by inhibiting synthesis and action of ethylene,... 

Saltveit ME and Mencarelli F. 1988. Inhibition of ethylene synthesis and action in ripening tomato fruit by ethanol vapors. J Am Soc Hort Sci 113 572—576. 

Ethylene not only hastens the ripening of fruit but also tends to promote senescence in all parts of plants. Its signaling mechanisms are the best-known for any plant hormone.368 369 Tire synthesis and action of ethylene are discussed in Chapter 24, Section D,4. Ethylene is metabolized slowly in plants by oxidation to ethylene oxide. The latter is hydrolyzed to form ethylene glycol, which is metabolized further to C02 (Eq. 30-3). 

These variations in behavior indicate that harvesting melons at different stages of maturity causes subsequent biochemical events involved in amino acid accumulation to follow markedly different pathways. Recent work shows that melon fhiit harvested up to ten days before commercial maturity exhibits climacteric behavior with respect to ethylene production showing that at least this aspect of ripening is not completely inhibited by premature separation from the plant(P). However, the amount of ethylene produced is dependent on maturity at harvest and fruit harvested five days prematurely generated only about half of the amount of ethylene produced by fruit harvested two days before maturity. Also the lag time required to initiate ethylene production after harvest depended on maturity and was longer for prematurely harvested fruit. Changes in the content of the phytohormone abscisic acid were also correlated with that of ethylene. However whether the different maturity related metabolic responses observed above result from the action of these or other plant hormones awaits further study. 

In order to keep fruit fresh, the ripening is slowed down by cold storage (cf. 18.1.5) and/or with additives which inhibit the formation or action of ethylene. 

A significant reduction in respiration rate takes place as the oxygen level is reduced below 21%, especially below 10%. Besides, the production and action of ethylene (CjH ) that plays a central role in ripening of the fruits can be inhibited at low... 

Alexander L, Grierson D (2002) Ethylene biosynthesis and action in tomato a model for climacteric fruit ripening. J Exp Bot 53 2039-2055... 

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