Promotion by Ethylene of the Capability to Convert 1-Aminocyclopropane-1-carboxylic Acid to Ethylene in Preclimacteric Tomato and Cantaloupe Fruits

Abstract

The intact fruits of preclimacteric tomato (Lycopersicon escukntum Mill) or cantaloupe (Cucumis melo L.) produced very little ethylene and had low capability of converting 1-aminocyclopropane-l-carboxylic acid (ACC) to ethylene. When these unripe tomato or cantaloupe fruits were treated with ethylene for 16 hours there was no increase in ACC content or in ethylene production rate, but the tissue's capability to convert ACC to ethylene increased markedly. Such an effect was also observed in fruits of tomato mutants rin and nor, which do not undergo ripening and the climacteric increase in ethylene production during the senescence. The development of this ethylene-forming capability induced by ethylene increased with increasing ethylene concentration (from 0.1 to 100 microliters per liter) and duration (I to 24 hours), when ethylene was removed this capability remained high for sometime (more than 24 hours). Norbornadiene, a competitive inhibitor of ethylene action, effectively eliminated the promotive effect of ethylene in tomato fruit. These data indicate that the development of the capability to convert ACC to ethylene in preclimacteric tomato and cantaloupe fruits are sensitive to ethylene treatment and that when these fruits are exposed to exogenous ethylene, the increase in ethylene-forming enzyme precedes the increase in ACC synthase.Climacteric fruits are characterized by a surge in ethylene production at the onset of ripening and ethylene treatment is known to hasten such a process. This phenomenon is referred to as autocatalytic ethylene production (1). The pathway ofethylene biosynthesis has been demonstrated to be: Met4 --SAM -. ACC ethylene by Adams and Yang (2). Since preclimacteric (unripe) fruits lack both ACC synthase and EFE, a massive increase in ethylene production requires development of both enzymes (20). It has been shown that at the onset of ripening, ACC synthase activity increases which is accompanied by an increase in ACC content (3,8,10,18 from the field when the fruits weighing approximately 500 g were still green externally and internally, and the netting of the fruits was incompletely developed; they were stored overnight at 25°C before use. Only those fruits producing less than 0.2 nl g-' h-' ethylene were used in experiments. For ethylene treatments intact fruits (two or more) or discs, which were cut from pericarp tissue of tomato fruits with a cork borer (0.5 cm diameter) and placed on a moistened paper in a Petri dish, were enclosed in 8.6-L jars containing a cup of KOH solution for absorbing CO2 released from tissues. The appropriate amount of ethylene was introduced by syringe and the concentration of ethylene was verified by gas chromatography. In ethylene-free air treatments a cup of Hg(Cl04)2 solution was placed in the jar; this kept the ethylene concentration below 0.02 ul 1`during the treatment period. In NDE treatment, appropriate amount of NDE was injected with a syringe into a piece of paper hung in the jar to facilitate evaporation. The concentration of NDE ...

Differential regulation of the tomato ETR gene family throughout plant development

“…The presence of LeETR mRNAs prior to ripening suggests that one or more gene products may contribute to ripening-independent ethylene perception processes in immature fruit. Indeed, while treatment of immature fruit with exogenous ethylene fails to induce ripening, such ethylene-regulated targets as ACC oxidase are known to be activated (Liu et al, 1985). Although the NR mRNA content of immature fruit is comparable to maximal mRNA levels of LeETR1 and LeETR2 throughout fruit growth and ripening, the presence of NR mRNA in amounts far below those evident upon subsequent ripening-associated accumulation of this mRNA (Wilkinson et al, 1995) and its associated protein (H.J.…”

Ethylene-Promoted Conversion of 1-Aminocyclopropane-1-Carboxylic Acid to Ethylene in Peel of Apple at Various Stages of Fruit Development

“…5). Ethylenepromoted EFE activity in preclimacteric cantaloupe or tomato fruit also required the continuous presence of ethylene for maximal response (14).…”

“…The onset of autocatalytic ethylene production is accompanied by an increase in ACC content as well as an increase in ACC synthase activity and increased conversion of ACC to ethylene (26). Ethylene treatment ofpreclimacteric cantaloupe or tomato fruit for a short period promotes the ability of the tissue to convert ACC to ethylene without promoting ACC synthesis (14). Ethylene or propylene treatment ofapples promotes the development ofACC synthase activity (4,5).…”

Extraction and Partial Characterization of the Ethylene-Forming Enzyme from Apple Fruit

“…cv Golden Delicious) fruits were harvested from a local orchard and each fruit was monitored for its ethylene production rate at 25°C. Intact preclimacteric fruits producing less than 0.1 nL g-' h-' were treated with 70 ,uL/L exogenous ethylene for various periods to promote the development of in vivo EFE activity (9).…”