Gum Formation by Methyl Jasmonate in Tulip Shoots is Stimulated by Ethylene

The promotive effect of methyl jasmonate (JA-Me) on the induction of gum in tulip shoots (Tulipa gesneriana L. cvs. Gudoshnik and Apeldoorn) was studied in the presence of ethylene. Gum formation in the stem and the basal part of the leaves was induced by JA-Me (1% w/w in lanolin) and stimulated strongly by the simultaneous application of 1 or 5 mm 1-aminocyclopropane-1-carboxylic acid (ACC). JA-Me at a concentration of 0.1% did not induce gum, but that together with ACC at a concentration of 1 or 5 mm induced it substantially. Although JA-Me stimulated ethylene production substantially in the stem of intact tulips, ethephon (1% w/w) or ACC (1 or 5 mm) did not induce gum formation in tulip shoots. JA-Me induced gum formation in tulip shoots even in the presence of aminooxyacetic acid or cobalt ions. Moreover, gum formation was also observed in the cut shoot applied with JA-Me as a solution at concentrations of 0.23 mm or more. These results strongly suggest that JA-Me is required for gum formation in tulip shoots, and ethylene probably makes the tissues of shoots sensitive to JA-Me. Received March 23, 1998; accepted June 10, 1998     

Effects of Methyl Jasmonate on Anthocyanin Accumulation, Ethylene Production, and CO2 Evolution in Uncooled and Cooled Tulip Bulbs

Effects of methyl jasmonate (JA-Me) on anthocyanin accumulation, ethylene production, and CO₂ evolution in uncooled and cooled tulips (Tulipa gesneriana L. cvs. Apeldoorn and Gudoshnik) were studied. JA-Me stimulated anthocyanin accumulation in stems and leaves from uncooled and cooled bulbs of both cultivars. The highest level of anthocyanin accumulation was observed in leaves from cooled bulbs treated with 200 μL/liter JA-Me. In sprouting bulbs treated with 100 μL/liter and higher concentrations of JA-Me, the ethylene production began to increase at 3 days after treatment, being extremely greater in uncooled bulbs than in cooled ones. JA-Me also stimulated CO₂ evolution in both cultivars, depending on its concentrations. CO₂ evolution in sprouting bulbs was not affected by cooling treatment. These results suggest that anthocyanin accumulation by JA-Me in tulip leaves is not related to ethylene production stimulated by JA-Me. Received October 10, 1997; accepted November 17, 1997     

Effect of methyl jasmonate on gummosis in petioles of culinary rhubarb (<Emphasis Type="Italic">Rheum rhabarbarum</Emphasis> L.) and the determination of sugar composition of the gum

This study aimed to know the key chemical compound influencing gummosis in petioles of intact growing culinary rhubarb (Rheum rhabarbarum L.) with special emphasis on its sugar composition. The application of methyl jasmonate (JA-Me, 0.5 and 1% in lanolin, w/w) in the middle of intact petiole of growing rhubarb substantially induced gummosis in the entire petioles, below and above the treatment, within several days. JA-Me at 0.5% in lanolin greatly stimulated ethylene production in intact petiole of growing rhubarb, on the 3rd day after JA-Me treatment, ethylene level being increased five times or more. However, an ethylene-releasing compound, ethephon (2-chloroethylphosphonic acid, 1 and 2% in lanolin, w/w) alone had no effect on gummosis. Analysis of gum polysaccharides by a gel permeation chromatography with a Tosho TSK-gel G5000PW gel permeation column revealed that almost all of rhubarb gum polysaccharides were eluted near the void in this gel chromatography system, suggesting that molecular mass of rhubarb gum polysaccharides are more than 500 kDa, while precise mass has not been decided in this study. Analysis of gum sugar composition after hydrolysis revealed that rhubarb gums is rich in galactose (ca. 30%), arabinose (ca. 20%), and galacturonic acid (15–20%), although other sugars also existed in small quantities. These results suggest that the key chemical compound of gummosis in petioles of rhubarb is jasmonates rather than ethylene, and gum polysaccharides consist of not only pectic arabinogalactans but also homogalacturonans.     

Methyl jasmonate stimulates the formation and the accumulation of anthocyanin in <Emphasis Type="Italic">Kalanchoe blossfeldiana</Emphasis>

Methyl jasmonate (JA-Me) at concentrations of 0.1, 0.5 and 1.0 % (w/w) greatly stimulated anthocyanins accumulation in shoots of young plants of Kalanchoe blossfeldiana when it was applied around the stem as a lanolin paste. Stimulatory effect of JA-Me was evidently observed as early as two days after treatment. Anthocyanins were formed in the main and lateral shoots, including petioles, both below and above portions of the treatment. When leaves were removed from the plant, almost no anthocyanin formation was observed. It should be mentioned that leaves are necessary for the anthocyanin accumulation in stems induced by JA-Me.     

Jasmonates are essential factors inducing gummosis in tulips: mode of action of jasmonates focusing on sugar metabolism

The purpose of this study was to know the mechanism of jasmonates to induce gummosis in tulip (Tulipa gesneriana L. cv. Apeldoorn) shoots, especially on the focus of sugar metabolism. Gummosis in the first internode of tulip plants was induced by the application of methyl jasmonate (JA-Me, 1% w/w in lanolin) and jasmonic acid (JA, 1% w/w in lanolin) 5 days after application and strongly stimulated by the simultaneous application of ethylene-releasing compound, ethephon (2-chloroethylphosphonic acid, 1% w/w in lanolin), although ethephon alone had little effect. JA-Me stimulated ethylene production of the first internodes of tulips, ethylene production increasing up to more than 5 times at day 1 and day 3 after the application. On the other hand, application of ethephon did not increase endogenous levels of jasmonates in tulip stems. Analysis of composition of tulip gums revealed that they were consisted of glucuronoarabinoxylan with an average molecular weight of ca. 700 kDa. JA-Me strongly decreased the total amount of soluble sugars in tulip stems even in 1 day after application, being ca. 50% of initial values 5 days after application, but ethephon did not. However, both JA-Me and ethephon had almost no effect on the neutral sugar compositions of soluble sugars mainly consisting of glucose, mannose and xylose in ratio of 20:2:1 and traces of arabinose. Both JA-Me and ethephon applied exogenously stimulated senescence of tulip shoots shown by the loss of chlorophyll. These results strongly suggest that the essential factor of gummosis in tulips is jasmonates affecting the sugar metabolism in tulip shoots. The mode of action of jasmonates to induce gummosis of tulip shoots is discussed in relation to ethylene production, sugar metabolism and senescence.     

Identification of jasmonic acid and its methyl ester as gum-inducing factors in tulips

The purpose of this study was to identify endogenous factors that induce gummosis and to show their role in gummosis in tulip (Tulipa gesneriana L. cv. Apeldoorn) stems. Using procedures to detect endogenous factors that induce gum in the stem of tulips, jasmonic acid (JA) and methyl jasmonate (JA-Me) were successfully identified using gas–liquid chromatography–mass spectrometry. Total amounts of JA and JA-Me designated as jasmonates in tulip stems were also estimated at about 70–80 ng/g fresh weight, using deuterium-labeled jasmonates as internal standards. The application of JA and JA-Me as lanolin pastes substantially induced gums in tulip stems with ethylene production. The application of ethephon, an ethylene-generating compound, however, induced no gummosis although it slightly affected jasmonate content in tulip stems. These results strongly suggest that JA and JA-Me are endogenous factors that induce gummosis in tulip stems.     

Inhibitory Effects of Methyl Jasmonate on the Germination and Ethylene Production in Cocklebur Seeds

Methyl jasmonate (JA-Me) inhibited the germination of cocklebur (Xanthium pennsylvanicum Wallr.) seeds. The inhibition of the germination of cocklebur seeds treated with JA-Me at concentrations less than 300 μm was nullified by ethylene applied exogenously, although the inhibitory effect of 1,000 μm JA-Me was not recovered completely even by high concentrations of ethylene (10,000 μL/liter). JA-Me inhibited ethylene production before seed germination. The level of 1-aminocyclopropane-1-carboxylic acid (ACC) in the cotyledonary tissues treated with JA-Me decreased but not the level of 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC). JA-Me inhibited the conversion of ACC to ethylene in the tissues. These results suggested that JA-Me inhibits ethylene production by prevention of ACC oxidation in addition to ACC synthesis. We believe that the inhibition of ethylene production by JA-Me results in the retardation of the germination of cocklebur seeds. Received June 4, 1997; accepted October 23, 1997     

Gummosis in grape hyacinth (Muscari armeniacum) bulbs: hormonal regulation and chemical composition of gums

The purpose of this study was to investigate the hormonal regulation of gummosis in grape hyacinth (Muscari armeniacum) bulbs, focusing especially on the chemical composition of the gums. The application of ethephon (2-chloroethylphosphonic acid), an ethylene-releasing compound, at 1% and 2% (w/w) in lanolin as well as ethylene induced gummosis in the bulbs within several days. Methyl jasmonate (JA-Me, 0.1–2% in lanolin) alone had no effect on gummosis. However, simultaneous application of JA-Me and ethephon led to extreme stimulation of ethephon-induced gummosis. Ethephon-induced gummosis in the bulbs depended on the maturation stage of the bulbs, increasing from April to July, but decreasing from August to September. Regardless of the presence of JA-Me, the application of ethephon to the inflorescence axis of grape hyacinths did not induce gummosis. Gel permeation chromatography analysis revealed that gums were homogenous polysaccharides with an average molecular mass of ca. 8.3 kDa. Analysis of the sugar composition of the gums after hydrolysis revealed that the molar ratio of Rha:Ara:Gal:GalA:GlcA was 25:10:40:7:15. These results suggest that principal factors of gummosis as well as the chemical composition of gums differ between species of bulbous plants.     

Ethephon-Induced Gummosis in Sour Cherry (Prunus cerasus L.) : I. Effect on Xylem Function and Shoot Water Status

Ethephon, (2-chloroethyl)phosphonic acid, was sprayed at concentrations up to 69.2 millimolar to enhance gum formation in 1-year-old shoots of mature Prunus cerasus L. cv Montmorency trees. Gum accumulation caused rupturing of the shoot periderm, followed by gum extrusion. Lower ethephon concentrations were required to induce gum formation in spring and early summer (1.7-3.5 millimolar) then in late summer and fall (13.8-69.2 millimolar). The number of functional vessels, shoot hydraulic conductance, and water potential of both leaf and internode tissue decreased as gum content of shoots increased. Nontreated control shoots also contained small quantities of gum. There was no difference in neutral sugar composition of gum exuded by the tree, obtained from aqueous shoot extracts, or flushed from the vessels of shoots, whether induced by ethephon or not. Severe decrease in shoot and leaf water potential was associated with shoot die-back. Recovery of xylem function may occur where gummosis is less severe. Discrepancy between measured and predicted hydraulic conductance increased as shoot gum content increased, suggesting that decrease in number of functional vessels alone was not sufficient to explain the effects of gum on loss of shoot hydraulic conductance. Increased gum content in those vessels remaining functional would increase vessel sap viscosity and further reduce hydraulic conductance. The viscosities necessary to account for discrepancy between measured and predicted hydraulic conductance were calculated. Gum concentration less than 1.0% (w/v) would produce these viscosities.     

The effect of methyl jasmonate and abscisic acid on differentiation of benzyladenine-induced bulblets inMuscari bulbs

Methyl jasmonate (JA-Me) at a concentration of 0.5% in lanolin paste totally inhibited bulblets formation induced by benzyladenine in intactMuscari bulbs. Lower concentrations of JA-Me delayed development and growth of bulblets induced by benzyladenine. It seems that methyl jasmonate acts as a powerful inhibitor of cell division induced by cytokinin in used test. In comparison with methyl jasmonate, abscisic acid did not show an inhibitory effect on bulblets formation induced by benzyladenine, even in a higher concentration.     

Relationship between stimulatory effect of methyl jasmonate on ethylene production and 1-aminocyclopropane-1-carboxylic acid content in tomatoes

The effect of methyl jasmonate (JA-Me) applied in concentration 1.0 % in lanolin paste to detached tomato fruits at the mature green, advanced mature green and light red stages on the ethylene production and l-aminocyclopropane-l-carboxylic acid (ACC) content was investigated at different times after treatment. JA-Me stimulated ethylene production in all stages of ripening, but the level of ACC increased or decreased in comparison with control depending on the stage of ripening. Higher level of ACC in JA-Me treated tissue was found in mature green stage and fully ripened tomatoes-treated at advanced green stage; lower one in light red stage — treated at advanced green stage and fully ripened stage - treated at light red stage.     

Transport of [1-14C]-indole-3-acetic acid in Abies balsamea shoots ringed with Ethrel

The terminal (1-year-old) shoot of dormant, 2-year-old Abies balsamea (L.) Mill. seedlings was ringed with 0 or 10 mg Ethrel g^-1 lanolin. After 5 weeks of culture under environmental conditions favorable for growth, some of the treated shoots were harvested to measure tracheid number by microscopy and ethylene evolution by gas chromatography-flame ionization detection. The remaining shoots were used to measure basipetal IAA transport in the cambial region by decapitating the shoot apex, applying a pulse of [1-¹⁴C]-IAA to the cut surface, and monitoring the subsequent distribution of radioactivity. Ringing with 10 mg Ethrel g^-1 lanolin, compared with lanolin alone, stimulated cambial region ethylene evolution about 26-fold at, and 3-fold above and below the ringing site, but promoted tracheid production at the ringing site only. Ethrel ringing also increased the velocity, after 26 h transport, at which the front of the [1-¹⁴C]-IAA pulse moved below the ringing site. After 72 h of [1-¹⁴C]-IAA transport, when only immobilized radioactivity was present, the amount of radioactivity recovered in shoots ringed with 10 mg Ethrel g^-1 lanolin was higher than with lanolin alone at the ringing site but lower below it. No difference was observed above the ringing site. The distribution of radioactivity was the same in shoots ringed with lanolin alone and in unringed shoots. The results support the hypothesis that an abnormally high cambial region concentration of ethylene derived from Ethrel ringing inhibits the capacity of basipetal IAA transport at the ringing site, resulting in a local accumulation of IAA that stimulates tracheid production.     

Reproductive Biology of Selaginella: I. Determination of Megasporangia by 2-Chloroethylphosphonic Acid, an Ethylene-releasing Compound

Control clumps of Selaginella wallacei Heiron., sprayed with distilled water with Tween 20, produced a high proportion of microsporangia. Similar clumps sprayed with 2-chlorethyl-phosphonic acid, and ethylene-releasing compound (Ethephon), at 7.65 and 76.5 mg/liter produced almost exclusively megasporangia. Treatment of Selaginella pallescens (Presl) Spring with Ethephon at 34 mg/liter caused the production of megasporangia in the microsporangiate files of the strobili. The possibility that ethylene may be involved in the regulation of heterospory in Selaginella is discussed.     

Ethylene in relation to compression wood formation in Abies balsamea shoots

 The terminal (1-year-old) shoot of dormant, 2-year-old balsam fir [Abies balsamea (L.) Mill.] seedlings was either left vertically oriented or tilted to an angle of 60° from the vertical (tilting experiment), or was ringed with N-1-naphthylphthalamic acid (NPA), an inhibitor of indole-3-acetic acid transport, at a concentration of 0, 1 or 10 mg g⁻¹ lanolin (NPA experiment). After 6 weeks of growth, ethylene evolution from the cambial region was measured by gas chromatography – flame ionization detection, and tracheid production and compression wood formation were determined by microscopy. In vertical seedlings of the tilting experiment and in 0 mg g⁻¹-treated seedlings of the NPA experiment, compression wood was not formed and neither ethylene evolution nor tracheid production varied longitudinally or circumferentially within the stem. Tilting induced compression wood formation and increased ethylene evolution and tracheid production on the lower side of the stem, while decreasing tracheid production on the upper side. Compression wood formation was induced and tracheid production and ethylene evolution were stimulated at and above the point where 1 or 10 mg NPA g⁻¹ was applied, whereas below this point compression wood was not formed and tracheid production was inhibited. In both tilting and NPA experiments, there was a positive correlation between ethylene evolution and tracheid production when data from all seedlings were analyzed, but not when data from seedlings forming compression wood were excluded. The results indicate that cambial region ethylene evolution is enhanced when compression wood is being formed, and that the enhancement is related to compression wood formation per se rather than the associated increase in tracheid production. Received: 19 February 1998 / Accepted: 26 October 1998     

POST-POLLINATION PHENOMENA IN ORCHID FLOWERS. IV. EFFECTS OF ETHYLENE

Treatment of Cymbidium (Orchidaceae) flowers with 10/μl/liter ethylene for up to 78 hr induces anthocyanin formation in both gynostemia (columns) and labella (lips). After that, pigment levels decrease. During 24-hr exposures, ethylene concentrations of 0.1, 1, and 10μl/ liter cause increased anthocyanin levels in both lips and columns. Ethylene also brings about color changes in the calli and wilting of the perianth, but it does not cause straightening of gynostemia and stigmatic closure. Emasculation effects are similar to those of ethylene, whereas pollination and NAA induce anthocyanin formation and closing of stigmas, as well as swelling and loss of curvature in gynostemia. The effects of ethylene are correlated with its action in other systems.     

Changes of Respiration Rate, Ethylene Evolution, and Abscisic Acid Content in Developing Inflorescence and Young Fruit of Olive (Olea europaea L. cv. Konservolia)

Simultaneous measurements of respiration, ethylene production, and abscisic acid (ABA) concentrations, as well as the growth parameters length, fresh weight (FW), and dry weight (DW) of olive (Olea europaea L. cv. Konservolia) inflorescence were carried out at short intervals (3–7 days) during the period from bud burst until the 3rd week after full bloom (AFB), when young fruit reached 8 mm in length. The axis of inflorescence elongated remarkably during the 3rd week after bud burst (ABB), massive bract shedding occurred during the 4th week ABB, full bloom (FB) was observed 7 weeks ABB, and massive floral organ abscission 1 week AFB. The results showed a continuous increase in inflorescence FW and DW from bud burst until 4 days before FB. Respiration rate, ethylene production, and levels of ABA were relatively high during the first 3 weeks ABB. After this period, respiration and ethylene followed a similar pattern of changes, inversely to that of ABA concentration. An accumulation of inflorescence ABA 6 and 4 days before FB was associated with the minimum values of respiration and ethylene production on the same dates. The sharp decrease in the ABA concentration during FB and 3 days later was followed by a high rise in ethylene and an increase in respiration rate, which both rose further 1 week AFB. The results suggest a possible correlation of ABA with the early stage of floral abscission, whereas ethylene production seems to be correlated with the terminal separatory activity in olive inflorescence abscission processes. Received May 28, 1998; accepted November 17, 1998     

The effect of methyl jasmonate on ethylene and l-aminocyclopropane-1-carboxylic acid production in apple fruits

Methyl jasmonate (JA-Me) at concentration of 0.5 % and 1.0 % in lanolin paste applied to the surface of postclimacteric apples cultivars McIntosh, Spartan, and Cortland inhibited ethylene production in slices of cortex with a skin cut to a depth of about 2 mm. The level of 1-aminocyclopropane-l-carboxylic acid (ACC) was decreased in tissues of apples treated with methyl jasmonate. Methyl jasmonate stimulated ethylene production in preclimacteric apples cv. McIntosh.     

In Vitro Propagation of Salt-Tolerant Wild Rice Relative, Porteresia coarctata Tateoka

Micropropagation of Porteresia coarctata Tateoka, a wild relative of rice with useful genetic traits of salinity and submergence tolerance, was achieved through nodal segment culture. Woody Plant (WP) medium supplemented with benzyladenine (5.5 μm) and kinetin (2.3 μm) gave the greatest response to initiation and multiplication. The multiplication rate of 11 shoots/explant with an average shoot length of 3.5 cm was observed after 8 weeks of culture period. The rooting response was observed simultaneously in the multiplication media, but subsequent establishment was poor. When the in vitro raised shoots were transferred to optimal 1/2 WP and 1/2 MS media with 10.7 μmα-naphthaleneacetic acid, the rooting response was enhanced. Such rooted plants were hardened successfully under field conditions. Received March 8, 1998; accepted October 12, 1998