Effect of point freezing on ethylene and ethane production by sugar beet leaf disks

Wound-induced ethylene synthesis by subapical stem sections of etiolated Pisum saivum L., cv. Alaska seedlngs, as described by Saltveit and Dilley (Plant Physiol 1978 61: 447450), was half-saturated at 3.6% (v/v) 02 and saturated at about 10% 02. Corresponding values for CO2 production during the same period were 1.1% and 10% 02, respectively. Anaerobiosis stopped all ethylene evolution and delayed the characteristic pattern of wound ethylene synthesis. Exposing tissue to 3.5% CO2 in air in a flowthrough system reduced wound ethylene synthesis by 30%. Enhancing gas diffusivity by reducing the total pressure to 130 mm Hg almost doubled the rate of wound ethylene synthesis and this effect was negated by exposure to 250 #1 liter-1 propylene. Applied ethylene or propylene stopped wound ethylene synthesis during the period of application, but unlike N2, no lag period was observed upon flushing with air. It is concluded that the characteristic pattern of wound-induced ethylene synthesis resulted from negative feedback control by endogenous ethylene.No wound ethylene was produced for 2 hours after excision at 10 or 38 C. Low temperatures prolonged the lag period, but did not prevent induction of the wound response, since tissue held for 2 hours at 10 C produced wound ethylene immediately when warmed to 30 C. In contrast, temperatures above 36 C prevented induction of wound ethylene synthesis, since tissue cooled to 30 C after 1 hour at 40 C required 2 hours before ethylene production returned to normal levels. The activation energy between 15 and 36 C was 12.1 mole kilocalories degree-'.A rapidly induced, transitory increase in the rate of ethylene synthesis has been observed in a variety of excised tissues (1,24). The wound response was recently characterized in Pisum sativum L., cv. Alaska (24). In subapical stem tissue wound-induced ethylene production at 25 C increased linearly after a lag period of 26 min from 2.7 nl g-' hr-' to the first maximum of 11.3 nl g-' hr-' at 56 min. The rate of production then decreased to a minimum at 90 min, increased to a lower second maximum at 131 min, and then declined over a period of about 100 min to about 4 nl g-' hr-'. The magnitude of the response varied slightly from experiment to experiment, but the time sequence was constant for tissue excised from a given region of the pea seedling. In this study we examined the 02 and temperature dependency of woundinduced ethylene synthesis by etiolated 'Alaska' pea stem sections.Vegetative, ripening, and senescent tissue require 02 for ethylene synthesis (1,3, 6,13,21,29

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confidence: 56%

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confidence: 99%

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Rapidly Induced Wound Ethylene from Excised Segments of Etiolated Pisum sativum L., cv. Alaska

Saltveit¹,

Dilley²

1978

“…Both chemical stress-inducing agents as well as hormonally active substances can stimulate the rate ofethylene evolution (1). Ethane evolution has proven to be a reliable indicator ofthe degree ofphysiological injury of plants in response to a variety of chemical or environmental stresses (8). During the course of the experiments described herein, TDZ was found to have no consistent effect on the rate of ethane evolution from treated tissues (data not presented).…”

Section: Discussionmentioning

confidence: 81%

Effect of the Defoliant Thidiazuron on Ethylene Evolution from Mung Bean Hypocotyl Segments

Suttle

1984

The effect of the defoliant thidiazuron (N-phenyl-N'1,2,3-thiadiazo1-5- (2,18), it is important to understand the biochemical mechanism(s) by which TDZ enhances its production. Etiolated mung bean hypocotyls have been used extensively as a model system for evaluating the effects ofmany compounds that either enhance ' Mention of trademark or proprietary product does not constitute a guarantee or warranty of the product by the United States Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.2 Abbreviations: TDZ, thidiazuron; AVG, aminoethoxyvinylglycine; PCIB, 2-p-chlorophenoxy-2-methyl propionic acid; ACC, I-aminocyclopropane-l-carboxylic acid; AIBA, a-aminoisobutyric acid; AOA, aminooxyacetic acid.or reduce the rate of ethylene production. As a first step toward understanding/defining the physiological basis(es) of the defoliating activity of TDZ, its effect on ethylene evolution was examined. This paper describes the effects of TDZ on ethylene evolution from mung bean hypocotyls and attempts to define the biochemical basis for this interaction. A preliminary report of this research has been presented (22). MATERIALS AND METHODSPlant Material and Experimental Procedure. Mung bean (Vigna radiata L. Wilczek) seeds were surface-sterilized by soaking in 1% (v/v) NaOCI (1:5 dilution of commercial bleach) for 5 min. The seeds were then rinsed in running distilled H20 for 4 h and were sown in flats containing vermiculite. Etiolated seedlings were raised in an incubator (25 ± 1C) for 6 d. Hypocotyl segments (1.5 cm) were prepared by excising a portion of the hypocotyl immediately below the closed hook. All manipulations were conducted under a low fluence, green safelight in a darkroom.All experiments described in this paper were repeated at least three times. Whenever possible, each treatment within an experiment was replicated (n = 3). Due to the nature of some of the experiments, replication within an experiment was not feasible. Data from a typical experiment are presented.Chemicals. Technical-grade TDZ was a gift from E. Pieters of Nor-Am Agricultural Products, Inc. Stock solutions of thidiazuron were prepared in DMSO. A DMSO concentration of 0.1% (v/v) was used in all studies (including controls). AVG was a gift from Dr. R. W. Bagley of HLR Sciences, Inc. AOA, chloramphenicol, a-amino-isobutyric acid, BSA, DL-DTT, Hepes, pyridoxal-5-phosphate, sucrose, and PCIB were purchased from Sigma Chemical Co. ACC and Mes were purchased from Calbiochem. (NH4)2 SO4 was purchased from Schwartz-Mann. Dose-Response Studies. Excised hypocotyl segments were placed in 25 ml flasks that contained 4 ml of treatment solution (10 segments/flask). The treatment solution consisted of 10 mM Mes/KOH buffer (pH 5.7) containing 2% (w/v) sucrose, 5 mM CaCl2, 50 gg/ml chloramphenicol ± various concentrations of TDZ. The flasks were sealed and were incubated in the dark (25C) for 24 h. At that time the headspace was sampled and the ethylene content determined by GC usi...

“…This has been noted for plant tissues subjected to salinity (3), wounding (4), freezing (4), and drought (21) …”

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confidence: 68%

Chilling-Induced Lipid Degradation in Cucumber (Cucumis sativa L. cv Hybrid C) Fruit

Parkin

Kuo²

1989

Chilling at 4°C in the dark induced lipid degradation in cucumber (Cucumis sativa L.) fruit upon rewarming at 14°C. Rates of ethane evolution by fruits rewarmed after 3 days of chilling were up to four-fold higher than those evolved by unchilled (140C) fruits (0.02-0.05 picomoles gram fresh weight-1 hour-'). This potentiation of lipid peroxidation occurred prior to irreversible injury (requiring 3 to 7 days of chilling) as indicated by increases in ethylene evolution and visual observations. Decreases in unsaturation of peel tissue glycolipids were observed in fruits rewarmed after 3 days of chilling, indicating the plastids to be the site of the early phases of chilling-induced peroxidation. Losses in unsaturation of tissue phospholipids were first observed only after chilling for 7 days. Phospholipase D activity appeared to be potentiated in fruits rewarmed after 7 days of chilling as indicated by a decrease in phosphatidylcholine (and secondarily phosphatidylethanolamine) with a corresponding increase in phosphatidic acid. These results indicate that lipid peroxidation may have a role in conferring chilling injury.examined as a primary response to chilling stress (in the absence of illumination), there is indirect evidence in the literature that suggests it may have a role in the development of chilling injury. The application of antioxidants to cucumber and pepper fruits delayed or reduced the severity of low temperature injury (26). Chilling also evokes a decrease in catalase activity in cucumber seedlings (18). These studies indicate that antioxidant defenses may be compromised in some CS plants exposed to low temperatures. In the special case where chilling is accompanied by illumination, photooxidation of cellular membranes is believed to play a role in the development of CI (22,28,29).We propose that lipid peroxidation may have a role in the development of CI, and undertook a study to provide an initial evaluation of this new hypothesis. Cucumber fruits were used as a model since the visual manifestations ofchilling injury in this tissue are well-defined (25, 26). There is also a lack of studies on CI in fruit tissues compared to whole plants, leaves, and other organs. Fruits were chilled in the absence of light to eliminate the contribution ofphotooxidative processes in the development of injury.Several theories have been advanced to account for the nature of CO.2 The primary lesion has been proposed to involve bulk membrane lipid phase transitions (12), unfavorable and direct low temperature effects on proteins and enzymes (7), the presence of high-melting membrane lipid species (15), and a redistribution of cellular calcium (13). Although data are available to support each of these theories, none appears to be universally accepted as the primary determinant of CI. The existence of a universal mechanism of CI is questionable and alternatively, several of the aforementioned factors may be required to confer low temperature sensitivity. There is also the possibility that some other unidentified ...