Protein Synthesis in Relation to Ripening of Pome Fruits

Upon initiation of ripening in avocado fruit (Persea americana Mill. cv Hass) with 10 microliters/liter ethylene, polysome prevalence and associated poly(A)' mRNA increase approximately 3-fold early in the respiratory climacteric and drop off to preclimacteric levels at the peak of the respiratory climacteric. The increase in poly(A)' mRNA on polysomes early in the respiratory climacteric constitutes a generic increase in constitutive mRNAs. New gene expression associated with ripening is minimal but evident after 10 hours of ethylene treatment and continues to increase relative to constitutive gene expression throughout the climacteric. The respiratory climacteric can be temporally separated into two phases. The first phase is associated with a general increase in protein synthesis, whereas the second phase reflects new gene expression and accumulation of corresponding proteins which may be responsible for softening and other ripening characteristics. A major new message on polysomes that arises concomitantly with the respiratory cimacteric codes for an in vitro translation product of 53 kilodaltons which is immunoprecipitated by antiserum against avocado fruit cellulase.Cyanide at 500 microliters/liter fails to affect the change in polysome prevalance or new gene expression associated with the ethylene-evoked climacteric in avocado fruit. Treatment of fruit with 500 microliters/liter cyanide alone initiates a respiratory increase within 4 hours, ethylene biosynthesis within 18 hours, and new gene expression akin to that educed by ethylene within 20 hours of exposure to cyanide.Several fruits show an increase in protein synthesis during the early stages of fruit ripening (23). In particular, Richmond and Biale (17) reported that, in avocado, amino acid incorporation into protein increased very early in the respiratory climacteric and diminished to less than preclimacteric levels at the peak of respiration. Although an increase in protein synthesis in several climacteric fruits has been demonstrated, its importance to the ripening process has been questioned (23). Brady and O'Connell (4) exposed 6-mm thick cross sections of banana fruit to 5 AI

supporting

confidence: 80%

“…McGlasson et al (12) and Frenkel et al (8) found that they could inhibit ripening of thick banana slices and Bartlett pear fruit, respectively, with cycloheximide but not the respiratory climacteric. Quazi and Freebairn (16) found that bananas ripened normally under diminished 02 tension, while having a much reduced respiratory climacteric.…”

mentioning

confidence: 99%

Interrelationship of Gene Expression, Polysome Prevalence, and Respiration during Ripening of Ethylene and/or Cyanide-Treated Avocado Fruit

Tucker¹,

Laties²

1984

“…Three days after the ethylene was administered, i.e. day 9 (Fig. 6), no difference in production rate between the ethylene-treated and untreated fruits was discerned.…”

Section: Resultsmentioning

confidence: 94%

“…The method used was essentially that of Frenkel et al (9) with modifications to improve distribution and to ensure sterility. The fruit were surface-sterilized in diluted household bleach (final sodium hypochlorite concentration 1.3%, w/v) for 15 min then rinsed thoroughly.…”

Section: Methodsmentioning

confidence: 99%

Effects of Aminoethoxyvinylglycine and Countereffects of Ethylene on Ripening of Bartlett Pear Fruits

Ness¹,

Romani²

1980

Pear fruits (Pyrss comnunis L. var. Bartlett) were treated with solutions containing aminoethoxyvinylglycine (AVG) using a modified vacuun infiltration method that introduced 43 milliliters solution per 100 grams tissue.At concentrations of 1 miimolar, AVG strongly inhibited ethylene production and delayed for 5 days the respiratory climacteric and accompanying ripening changes in skin color and flesh firmness. AVG was less effective in inhibiting the ripening of more mature fruits. Fruit infiltrated with 5 mHimolar AVG had not begun to ripen 12 days after initiation of ripening in the controls. When treated with ethylene the inhibited fruit exhibited a climacteric rise in respiration, softened, and became yeilow.Treatment of the AVG infiltrated fruits with ethyelne for 24 hours resulted in no recovery in endogenous ethylene production, but in a stimulation of protein synthesis measured as a 200% increase in leucine incorporation by excised tissue and a 74% increase in the percentage of ribosomes present as polysomes.Pears which have developed a "ripening capacity" will ripen in response to ethylene that is either applied or which has accumulated endogenously to a critical concentration. As they ripen, the fruit produce a large quantity of ethylene. The gas thus undoubtedly plays a role in the ripening of these and many other fruits, but it is not yet known how its production is triggered nor how it initiates the ripening process (1,11,16). In 1975, Lieberman et al. (12) showed that AVG3, a derivative of the antibiotic rhizobitoxine, strongly inhibited ethylene production by a variety of plant tissues. AVG and related compounds are recognized as potentially useful tools for probing both the biosynthesis ofethylene and its action. The specificity of inhibitors can, however, always be questioned. AVG is believed to block ethylene synthesis between S-adenosylmethionine and 1-aminocyclopropane-l-carboxylic acid (1, 5). It may interfer with other pyridoxal phosphate-dependent reactions (10) and may also inhibit tRNA charging (3).Wang and Mellenthin (20) infiltrated intact Anjou and Bartlett pears with solutions of AVG. They found that ethylene production was at least partially inhibited in both varieties. However, the ripening of Bartletts was not affected, whereas that of the Anjous was delayed by about 2 days. The present investigation relates an effective delay of Bartlett fruit ripening by AVG and the subsequent release of the inhibition by treatment with ethylene.

“…It is clear that fruit ripening is a complex of several processes which may be unrelated to one another once they have been initiated by ethylene in its role as the fruit ripening hormone (11,12,15). Although it has been thought that the respiratory increase in ripening fruits might be regarded as the summation of the energy requirements of other events in the ripening complex, recent work (5,6,18) (4. 14).…”

Section: Effect Of Ethylene Treatment On the Respiration Of Potatomentioning

confidence: 99%

Effects of Ethylene on Potato Tuber Respiration

Reid

Pratt

1972

Treatment of potato tubers (Solanum tuberosum L.) with ethylene gas causes a rapid rise in their respiration rate, reaching 5 to 10 times the rate of untreated tubers over 30 hours of treatment and then falling slowly. The response shows a lag of 8 hours, and more than 24 hours of exposure is required for maximum effect; the temperature optimum is near 25 C. In sensitivity to low concentrations and dependence on temperature, the phenomenon is similar to the effect of ethylene on the respiration of climacteric and nonclimacteric fruits. Treated potato tubers returned to air recover their sensitivity to ethylene more slowly than do nonclimacteric fruits (e.g., mature green oranges). It is proposed that the respiratory rise characteristic of ripening in climacteric fruits and of the wound response in plant tissues is induced by a rise in endogenous tissue ethylene.Ethylene is a plant hormone having diverse effects on a wide range of plant tissues. In spite of its apparent importance as a regulator of plant growth, the site and mechanisms of its actions have not yet been elucidated (10, 12). We recently described the remarkable effect of this substance on the respiration of intact potato tubers (14) and suggested the possible value of the phenomenon as a simple system for the study of the mode of action of ethylene. We report here a more detailed study of the respiratory response of potato tubers to ethylene gas and discuss the mechanisms that may be involved. MATERIALS AND METHODSMature (100 day) potato tubers (Solanum tuberosum L., cv. White Rose) were dug from the field, washed, and stored at 20 C until needed; all experiments except the temperature trial were conducted at this temperature. Commercially obtained tubers were found to be unsatisfactory because previous cold storage and careless handling may have had pronounced effects on their physiology. Mature green sweet oranges (Citrus sinensis Osbeck, seedling) were obtained from a local garden.Respiration measurements were made by placing individual specimens in 500-ml jars ventilated with a stream of air flowing at about 1.5 liter per hr and measuring the CO, content of the effluent air by gas chromatography. Ethylene was in-'This work was supported in part by research grant FD-00071 from the United States Public Health Service.2 On leave from Plant Diseases Division, D.S.I.R., Auckland, New Zealand. troduced into gas streams from a pressure cylinder through a reduction valve and appropriate capillary flowmeters, and the final concentration was verified with a gas chromatograph.When it was necessary to measure respiration in a static system, individual specimens were placed in 9-liter jars, and ethylene in appropriate amounts was added through a rubber septum. Samples of the jar atmosphere were taken through the septum for determination of the CO2 content. Changes in concentration resulting from sample removal were insignificant, and the jar volume was such that the concentration of CO2 seldom rose above 0.5%. RESULTS Effect of Ethylene Treatment on ...