The Effect of Low Temperature on Ethylene Production by Leaf Tissue of Phaseolus vulgaris L.

When leaf discs cut from primary leaves of Phaseolus vulgarisL. cv. Masterpiece plants grown at 25°C were incubated attemperatures below 25 °C, basal and wound ethylene productioncontinued at reduced rates. In both cases detectable levelsof ethylene were produced at 25 °C. When the rates of ethyleneproduction were plotted according to the Arrhenius equationa marked discontinuity was found at 11.4 °C which is consistentwith a membrane phase-transition at the critical chilling temperatureof the plant. Activation energies for the rate-limiting enzymereaction in ethylene production above and below the criticaltemperature have been calculated and the data interpreted asindicating the involvement of membrane-bound enzyme systemsin the biosynthesis of basal and wound ethylene. ethylene, temperature, Arrhenius plot, activation energy, Phaseolus vulgaris L., bean     

A Relationship between Membrane Permeability and Ethylene Production at High Temperature in Leaf Tissue of Phaseolus vulgaris L.

Leaf discs cut from primary leaves of Phaseolus vulgaris L cvMasterpiece were incubated at temperatures higher than the growthtemperature of 25 °C Both basal and wound ethylene productionincreased up to temperatures of 35–37 5 °C, thereafterdeclining rapidly There was no detectable ethylene productionat temperatures above 42 5 °C Exposure of leaf discs tohigh temperature for 60 mm resulted in a large production ofwound ethylene when they were returned to 25 °C The magnitudeof ethylene production was related to the initial incubationtemperature as was the length of the lag period before maximumproduction was achieved The results are discussed in relationto the requirement for continued membrane integrity for ethyleneproduction ethylene, temperature, membrane permeability, Phaseolus vulgaris L, dwarf bean     

Wound-Induced Ethylene Production and 1-Aminocyclopropane-1-carboxylic Acid Synthase in Mesocarp Tissue of Winter Squash Fruit

Discs (9 mm in diameter and 2 mm in thickness) sliced from mesocarpof winter squash fruit (Cucurbita maxima Duch.) upon incubationat 24°C produced ethylene at an increasing rate after alag period of 3 h. 1-Aminocydopropane-l-carboxylic acid (ACC)synthase activity also increased at a rapid rate after lag periodof less than 3 h, reaching a peak 14 h after incubation andthen declining sharply. The rise in ACC synthase activity precededa rapid increase in ACC formation and ethylene production. Inductionof ACC synthase by wounding in sliced discs was strongly suppressedby the application of cycloheximide, actinomycin D and cordycepin,suggesting that the rise in ACC synthase activity may resultfrom de novo synthesis of protein. ACC synthase extracted from wounded tissue of winter squashmesocarp required pyridoxal phosphate for its maximum activity.The optimum pH of the reaction was 8.5. Km value for S-adenosylmethioninewas 120 µM. The reaction was markedly inhibited by aminoethoxyvinylglycinewith Ki value being 2.7 µM. (Received March 23, 1983; Accepted May 23, 1983)     

Ethylene Biosynthesis and Cadmium Toxicity in Leaf Tissue of Beans (Phaseolus vulgaris L.)

Stress ethylene production in bean (Phaseolus vulgaris L., cv. Taylor's Horticultural) leaf tissue was stimulated by Cd²⁺ at concentrations above 1 micromolar. Cd²⁺-induced ethylene biosynthesis was dependent upon synthesis of 1-aminocyclopropane-1-carboxylic acid (ACC) by ACC synthase. Activity of ACC synthase and ethylene production rate peaked at 8 h of treatment. The subsequent decline in enzyme activity was most likely due to inactivation of the enzyme by Cd²⁺, which inhibited ACC synthase activity in vitro at concentrations as low as 0.1 micromolar. Decrease in ethylene production rate was accompanied by leakage of solutes and increasing inhibition of ACC-dependent ethylene production. Ca²⁺, present during a 2-hour preincubation, reduced the effect of Cd²⁺ on leakage and ACC conversion. This suggests that Cd²⁺ exerts its toxicity through membrane damage and inactivation of enzymes. The possibility of an indirect stimulation of ethylene biosynthesis through a wound signal from injured cells is discussed.     

In Vivo Nitrite Reduction in Leaf Tissue of Phaseolus vulgaris L

Experiments were performed to establish a procedure for in vivo measurement of nitrite utilization by leaf tissue of bean (Phaseolus vulgaris L. cv. Top Crop).     

Tissue Cultures of Phaseolus vulgaris L.

Abstract

Callus production and plant regeneration from different explants of Phaseolus vulgaris L. cv. Giza are reported. Calli cultures were induced from leaf, hypocotyl, embryo and root explants. Rapid growth of callus was achieved by leaf explants cultured on MS salts, B5 vitamins and supplemented with 2,4— dichlorophenoxyacetic acid (2, 4—D)+0.5 mg/l kinetin (kin). Addition of casein hydrolysate at 2 g/l to maintenance medium enhanced callus growth and hindered the early appearance of necrotic parts. This report also provides a detailed method for production of multiple shoots directly from the wounded edges of immature cotyledon explant via organogenesis on 1 mg/l benzyladenine (BA) or indirectly on 0.5 mg/l naphthaleneacetic acid (NAA)+2 mg/l BA. The regeneration of bean plants through the two ways described here (direct or indirect) may be of use in genetic improvement of bean.     

Changes in 1-Aminocyclopropane-1-carboxylic Acid Content and Ethylene Production in Hiproly Barley Callus during Differentiation

During differentiation after auxin withdrawal, the change in the ethylene production of Hiproly barley callus paralleled the change in 1-aminocyclopropane-1-carboxylic acid (ACC) content. The levels of ACC and ethylene production decreased rapidly, and then increased in Hiproly barley callus.

Aminooxyacetic acid (AOA) prevented the ACC and ethylene production of the callus. Moreover, aminoisobutyric acid (AIB) also inhibited the ethylene production, but did not prevent the ACC synthesis of the callus. On the other hand, methylglyoxal-bis(guanylhydrazone) (MGBG) greatly enhanced the ACC and ethylene production. Formation of adventitious roots in Hiproly barley callus was enhanced by the cultivation in the medium containing AIB or AOA. However, differentiation of the callus was strongly inhibited by MGBG.

Thus, prevention of ethylene production may be significant for differentiation of Hiproly barley callus.     

Some Characteristics of the System Converting 1-Aminocyclopropane-1-carboxylic Acid to Ethylene

The rate of C₂H₄ production in plant tissue appears to be limited by the level of endogenous 1-aminocyclopropane-1-carboxylic acid (ACC). Exogenous ACC stimulated C₂H₄ production considerably in plant tissues, but this required 10 to 100 times the endogenous concentrations of ACC before significant increases in C₂H₄ production were observed. This was partially due to poor penetration of ACC into the tissues. Conversion of ACC to C₂H₄ was inhibited by free radical scavengers, reducing agents, and copper chelators, but not by inhibitors of pyridoxal phosphate-mediated reactions. The system for converting ACC to C₂H₄ may be membrane-associated, for it did not survive treatment with surface-active agents and cold or osmotic shock reduced the capacity of the system to convert ACC to C₂H₄. The reaction rate was sensitive to temperatures above 29 and below 12 C, which suggests that the system may be associated with membrane-bound lipoproteins. The data presented support the possibility that the conversion of exogenous ACC to C₂H₄ proceeds via the natural physiological pathway.     

Ethylene Production and 1-Aminocyclopropane-1-Carboxylic Acid Conjugation in Thermoinhibited Cicer arietinum L. Seeds

The effect of supraoptimal temperatures (30°C, 35°C) on germination and ethylene production of Cicer arietinum (chick-pea) seeds was measured. Compared with a 25°C control, these temperatures inhibited both germination and ethylene production. The effect of supraoptimal temperatures could be alleviated by treating the seeds with ethylene. It was concluded that one effect of high temperature on germination was due to its negative effect on ethylene production. This inhibitory effect of high temperature was due to increased conjugation of 1-aminocyclopropane-1-carboxylic acid to 1-(malonylamino)cyclopropane-1-carboxylic acid and to an inhibition of ethylene-forming enzyme activity.     

Cytokinin Effects on Leaf Architecture in Phaseolus vulgaris L.

Treatment of expanding primary leaves of bean plants (Phaseolnsvulgaris L. cv. Limburgse vroege) with benzyladenine (BA) orkinetin at 0.5 mM for five consecutive days resulted in thickerleaves showing a significant decrease in intercellular air spacevolume. Compared with control plants, exposed mesophyll cellsurface area was lower per unit tissue volume, but unchangedwhen expressed per unit leaf surface area. Stomata of treatedplants were not fully closed in the dark and they did not openas wide as controls in the middle of the light period, suggestingthat the treatment resulted in impaired stomatal action. Allthe effects mentioned were more pronounced after treatment withBA, compared to kinetin. In spite of their magnitude, the observedchanges in leaf structure and function did not seem to havean important effect on total leaf diffusion resistance to carbondioxide during the course of the light period. Key words: Cytokinins, Leaf architecture     

Lateral Bud Growth in Phaseolus vulgaris L. and the Levels of Ethylene in the Bud and Adjacent Tissue

Ethephon and the ethylene inhibitors Ag⁺ and aminoethoxyvinylglycine (AVG) inhibited outgrowth of the axillary bud of thefirst trifoliate leaf in decapitated plants of Phaseolus vulgaris.Endogenous ethylene levels decreased in the stem upon decapitationalthough it is not conclusive that a causal relationship existsbetween this decrease and the release of axillary buds frominhibition. The proposition that auxin-induced ethylene is responsiblefor the suppression of axillary bud growth in the decapitatedplant when the apical shoot is replaced by auxin is not borneout in this study. Application of IAA directly to the axillarybud of intact plants gave rise to a transient increase in budgrowth. This growth increment was annulled when AVG was suppliedwith IAA to the bud despite the fact that the dosage of AVGused did not affect the normal slow growth rate of the bud ofthe intact plant or bud outgrowth resulting from shoot decapitation.     

Hypobaric Control of Ethylene-Induced Leaf Senescence in Intact Plants of Phaseolus vulgaris L

A controlled atmospheric-environment system (CAES) designed to sustain normal or hypobaric ambient growing conditions was developed, described, and evaluated for its effectiveness as a research tool capable of controlling ethylene-induced leaf senescence in intact plants of Phaseolus vulgaris L.

Senescence was prematurely-induced in primary leaves by treatment with 30 parts per million ethephon. Ethephon-derived endogenous ethylene reached peak levels within 6 hours at 26°C. Total endogenous ethylene levels then temporarily stabilized at approximately 1.75 microliters per liter from 6 to 24 hours. Thereafter, a progressive rise in ethylene resulted from leaf tissue metabolism and release. Throughout the study, the endogenous ethylene content of ethephon-treated leaves was greater than that of nontreated leaves.

Subjecting ethephon-treated leaves to atmospheres of 200 millibars, with O₂ and CO₂ compositions set to approximate normal atmospheric partial pressures, prevented chlorophyll loss. Alternately, subjecting ethephon-treated plants to 200 millibars of air only partially prevented chlorophyll loss. Hypobaric conditions (200 millibars), with O₂ and CO₂ at normal atmospheric availability, could be delayed until 48 hours after ethephon treatment and still prevent most leaf senescence. In conclusion, hypobaric conditions established and maintained within the CAES prevented ethylene-induced senescence (chlorosis) in intact plants, provided O₂ and CO₂ partial pressures were maintained at levels approximating normal ambient availability.

An unexpected increase in endogenous ethylene was detected within nontreated control leaves 48 hours subsequent to relocation from winter greenhouse conditions (latitude, 42°00″ N) to the CAES operating at normal ambient pressure. The longer photoperiod and/or higher temperature utilized within the CAES are hypothesized to influence ethylene metabolism directly and growth-promotive processes (e.g. response thresholds) indirectly.

     

Induction of 1-Aminocyclopropane-1-carboxylic Acid Synthase in Wounded Mesocarp Tissue of Winter Squash Fruit and the Effects of Ethylene

1-Aminocyclopropane-1-carboxylic acid (ACC) synthase activityincreased rapidly after wounding of mesocarp tissue of wintersquash fruit (Cucurbita maxima Duch.) and reached a peak at16 h after excision and then declined sharply. The rise in ACCsynthase activity was followed by increases in the endogenousACC content and the rate of ethylene production. The activityof ethylene forming enzyme (EFE) also increased rapidly in theexcised discs of mesocarp of winter squash fruit. ACC synthase activity was strongly inhibited by aminoethoxyvinylglycinewith a Ki value of 2.1 µM. Michaelis-Menten constant ofACC synthase for S-adenosylmethionine was 13.3 µM. Ethylene suppressed the induction of ACC synthase in the woundedmesocarp tissue. The suppression by ethylene increased withthe increasing concentrations of applied ethylene and the maximumeffect was obtained at about 100 µl 1^–1 ethylene,at which point the induction was suppressed by 54%. Ethylenedid not inhibit ACC synthase activity, nor did it suppress theinduction of EFE, but rather it slightly enhanced the latter. (Received August 24, 1984; Accepted October 29, 1984)     

Physiological Stress and Crystallites in Leaf Plastids of Phaseolus vulgaris L.

Crystalline inclusions were found in leaf plastids of Phaseolusvulgaris L. cultivar Limburg when excised plant parts were used.Removal of the root system induced crystalloid production afteran incubation period of optimal length. In agreement with thefindings of other authors physiological stress seems to be theunderlying condition of crystal formation in plastids.     

Regulation of Auxin-induced Ethylene Production in Mung Bean Hypocotyls: Role of 1-Aminocyclopropane-1-Carboxylic Acid

Ethylene production in mung bean hypocotyls was greatly increased by treatment with 1-aminocyclopropane-1-carboxylic acid (ACC), which was utilized as the ethylene precursor. Unlike auxin-stimulated ethylene production, ACC-dependent ethylene production was not inhibited by aminoethoxyvinylglycine, which is known to inhibit the conversion of S-adenosylmethionine to ACC. While the conversion of methionine to ethylene requires induction by auxin, the conversion of methionine to S-adenosylmethionine and the conversion of ACC to ethylene do not. It is proposed that the conversion of S-adenosylmethionine to ACC is the rate-limiting step in the biosynthesis of ethylene, and that auxin stimulates ethylene production by inducing the synthesis of the enzyme involved in this reaction.     

Leaf Growth in Phaseolus vulgaris: 2. Temperature Effects and the Light Factor

Results are reported for two experiments in which bean plantswere grown in a range of daylengths from i hour to continuousillumination at temperatures of 15^° C and 25^° C. Markeddifferences in total leaf area and in areas of individual leaveswere found, and these are related in a quadratic fashion withtotal radiation received per day. With high levels of radiationa decrease in leaf area was noted, and this is not explicablein terms of a simple nutritional hypothesis. There are pronouncedeffects of total radiation on specific leaf area but the mechanismby which these effects are brought about is not clear. The mostimportant influence of temperature on the expansion of the leafsurface appear to be: firstly, by controlling the rate at whichleaves unfold from the stem apex; and secondly, by controllingthe partition of dry matter between the leaves and the restof the plant. No effects of daylength on vegetative developmentwere found.     

The Rhythmic Leaf Movements after Regeneration of Partially Excised Pulvinus in Phaseolus vulgaris L.

Unlike the petiole or stem, the laminar pulvinus of the primaryleaves of Phaseolus vulgaris L. regenerated after a partialexcision. The histological and physiological aspects of theseregeneration processes have been studied. On the third day afterthe excision of the flexor (or extensor) region, the pulvinuswas regenerated. When the major part of the extensor was cutaway, the period and phase of the circadian leaf movements wereunchanged whereas the amplitude was greatly reduced. When theflexor region was excised, period, phase and amplitude weremaintained. Some changes could be seen in the ultradian movementsafter excision of flexor as well extensor regions. (Received August 31, 1988; Accepted March 30, 1989)     

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

The intact fruits of preclimacteric tomato (Lycopersicon esculentum Mill) or cantaloupe (Cucumis melo L.) produced very little ethylene and had low capability of converting 1-aminocyclopropane-1-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 (1 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.