Synergistic effect of calcium and kinetin on ethylene production by the mungbean hypocotyl

Lau, Oi‐Lim; Yang, Shang Fa

doi:10.1007/bf00390497

Cited by 36 publications

(25 citation statements)

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“…Bars indicate SE. studies found a 6 h lag period in kinetin-induced ethylene production in etiolated mung bean hypocotyl segments (7). Previous studies in this laboratory have found a readily measurable increase in ethylene production from etiolated mung bean hypocotyl segments within 2 h of TDZ treatment (13).…”

Section: Discussionmentioning

confidence: 64%

“…In cotton, TDZ was far more effective than the auxin 2,4-D in stimulating ethylene production while in sunflower the reverse was true. Cytokinins have been shown to enhance ethylene production in root (12), epicotyl (3), hypocotyl (7,13) and leaf tissues (2,9,14). In these cases the cytokinins studied were much less effective than auxins and the maximum stimulation observed was generally small (less than 10 x control).…”

Section: Discussionmentioning

confidence: 98%

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Cytokinin-Induced Ethylene Biosynthesis in Nonsenescing Cotton Leaves

Suttle

1986

Plant Physiol.

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The influence of cytokinins on ethylene production was examined using cotton leaf tissues. Treatment of intact cotton (Gossypium hirsutum L. cv LG 102) seedlings with both natural and synthetic cytokinins resulted in an increase in ethylene production by excised leaves. The effectiveness of the cytokinins tested was as follows: thidiazuron >> BA >> isopentyladenine 2 zeatin >> kinetin. Using 100 micromolar thidiazuron (TDZ), an initial increase in ethylene production was observed 7 to 8 hours posttreatment, reached a maximum by 24 hours and then declined. Inhibitors of I-aminocyclopropane-l-arboxylic acid (ACC) synthesis and its oxidation to ethylene reduced ethylene production 24 hours post-treatment; however, by 48 hours only inhibitors of ACC oxidation were effective. The increase in ethylene production was accompanied by a massive accumulation of ACC and its acid-labile conjugate. TDZ treatment resulted in a significant increase in the capacity of tissues to oxidize ACC to ethylene. Endogenous levels of methionine remained constant following TDZ treatment. It was concluded that the stimulation of ethylene production in cotton leaves following cytokinin treatment was the result of an increase in both the formation and oxidation of ACC.

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Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 98%

Cytokinin-Induced Ethylene Biosynthesis in Nonsenescing Cotton Leaves

Suttle

1986

Plant Physiol.

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“…We have demonstrated a synergistic stimulation of ethylene production by kinetin and Ca2` (12). Three mechanisms are possible to account for the interaction between kinetin and Ca2" ions: (a) Ca2+ affects the uptake and metabolism of kinetin, which is in turn responsible for ethylene production; (b) kinetin affects the uptake or transport of Ca2, ( 55,1975 Plant Physiol.…”

Section: Discussionmentioning

confidence: 95%

“…We have previously reported a large synergistic increase in ethylene production by mung bean (Phaseoluts aureus Roxb) hypocotyl segments when kinetin and Ca2+ were applied (12). The amount of ethylene produced was dependent on the concentrations of kinetin and Ca2+ ion applied.…”

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confidence: 96%

Interaction of Kinetin and Calcium in Relation to Their Effect on Stimulation of Ethylene Production

Lau¹,

Yang²

1975

Plant Physiol.

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Application of kinetin and Ca2+ caused a striking synergistic increase in ethylene production by mung bean (Phaseolus aureus Roxb) hypocotyl segments. The effect of kinetin on Ca2+ uptake and of Ca'+ on the uptake and metabolism of kinetin in relation to their effect on ethylene production was studied. Tracer experiments showed that kinetin greatly increased the uptake of 4"Ca2' after 6 hours of incubation. Reciprocallv, Ca2+ stimulated the uptake of kinetin-8-14C and remarkably enhanced the metabolism of kinetin-8-14C into several polar metabolites. Consequently, the quantity of free kinetin-8-'4C remaining in Ca2+-treated segments was much less than in control segments. A possible mechanism accounting for the synergism between kinetin and calcium on ethylene production is discussed.We have previously reported a large synergistic increase in ethylene production by mung bean (Phaseoluts aureus Roxb) hypocotyl segments when kinetin and Ca2+ were applied (12). The amount of ethylene produced was dependent on the concentrations of kinetin and Ca2+ ion applied. Analysis of the synergistic effect of kinetin and Ca2+ on ethylene production required examination of the effect of kinetin on the uptake of Ca>2 and the reciprocal effect of Ca+ on the uptake and metabolism of kinetin. This paper describes the stimulatory effect of kinetin on Ca2+ uptake and of Ca>2 on kinetin uptake and metabolism. A possible mechanism accounting for the synergism between kinetin and Ca2+ ion on ethylene production is discussed. MATERIALS AND METHODSSeeds of mung bean (Phaseolus aureus Roxb) were grown in vermiculite for 3.5 days in darkness at 24 C. Segments 2 cm long were cut from hypocotyls at a point 1 cm below the hook, as previously described (11). Lots of 20 segments were incubated in 5 ml of a medium consisting of 50 mM potassium phosphate buffer (pH 6), 2% sucrose, and a given concentration of labeled and unlabeled kinetin or Ca2+, as indicated, in a 50-ml Erlenmeyer flask. A plastic centerwell containing 0.2 ml of 40% KOH was hung in the flask to absorb the CO2 evolved. The flasks were sealed with rubber serum caps and incubated in a shaker at 27 C in darkness.At the time intervals indicated, 1 -ml gas samples were 1 This work was supported by National Science Foundation Grant GB-33907X.withdrawn by hypodermic syringe, and ethylene was assayed with a gas chromatograph equipped with an alumina column and a flame ionization detector. The flask was then flushed with air and recapped for the next determination.For uptake studies, the hypocotyls incubated with 4"Ca'+ (104 /Ci, 41.5 ,umoles) were washed with five changes of distilled H20. The tissue was then ground in a glass homogenizer in 4 ml of 95% ethanol. The debris was pelleted by centrifugation and the supernatant was collected. The pellet was serially extracted with 2 ml of H20; 2 ml, 3 ml, and 5 ml of 10 mM HCl; and lastly with 5 ml of 0.5 mM EDTA. The radioactivity of the incubation medium, of each extract, and of the debris was determined with a liquid scintillation ...

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“…Cytokinins are more effective in stimulating ethylene production in conjunction with auxin, particularly in young tissue (Fuchs and Lieberman, 1968;Aharoni et al, 1979). Lau and Yang (1974) reporteti that the stimulation of ethylene production by cytokinin in conjunction with auxin was different from the stimiilation by cytokinin plus Ca2+. In particular, the time couise for the production of ethylene differed under the two cmditions.…”

Section: Coupling Cytokinin Action To Ethylenementioning

confidence: 99%

Cytokinin Action Is Coupled to Ethylene in Its Effects on the Inhibition of Root and Hypocotyl Elongation in Arabidopsis thaliana Seedlings

1995

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and Ecker, 1990). Some of these features have been utilized in the isolation of mutants with altered responses to ethylene . Ethylene-resistant mutants (ein or etr mutants) were identified by selecting seedlings that fail to express the triple response in the presente of ethylene. Other mutants were identified that pr0duc-d a triple-response phenotype constitutively, i.e. when no ethylene was applied. These mutants have been grouped into two classes, ethylene overproducers (eto) and constitutive triple-response mutants (ctr), distinguished on the basis of whether the phenotype is suppressed by inhibitors Of ethYlene biosynthesis Or action (Guzmán and Eckerr l990). Through epistasis analysis of the mutants, ethylene-response genes have been ordered on an unbranched pathway . Interestingly, ein or etr mutants appear to have very little effect on the normal growth and development of light-grown Arabidopsis seedlings in the absence of supplied ethylene.We have examined the relationship between cytokinin and ethylene responses in Arabidopsis seedlings and have found that ethylene largely mediates a number of responses to exogenous cytokinin, such as the inhibition of root and hypocotyl elongation. Cytokinin stimulates ethylene production, which, in turn, inhibits root and darkgrown hypocotyl elongation. Because of that, the effects of cytokinin on root and hypocotyl elongation can be blocked, in part, by the action of ethylene inhibitors or by ethylene mutants. These results constitute genetic proof of the idea put forth by Lieberman (1979) that cytokinin is coupled to ethylene action in seedlings.Cytokinins have profound effects on seedling development in Arabidopsis thaliana. Benzyladenine (BA) inhibits root elongation in light-or dark-grown seedlings, and in dark-grown seedlings BA inhibits hypocotyl elongation and exaggerates the curvature of apical hooks. The latter are characteristic ethylene responses and, therefore, the possible involvement of ethylene in BA responses was examined in seedlings. It was found that the inhibitory effects of BA on root and hypocotyl elongation were partially blocked by the action of ethylene inhibitors or ethylene-resistant mutations (ein7-7 and ein2-7). Ethylene production was stimulated by submicromolar concentrations of BA and could account, in part, for the inhibition of root and hypocotyl elongation. It was demonstrated further that BA did not affect the sensitivity of seedlings to ethylene. Thus, the effect of cytokinin on root and hypocotyl elongation in Arabidopsis appears to be mediated largely by the production of ethylene. The coupling between cytokinin and ethylene responses is further SUPported by the discovery that the cytokinin-resistant mutant ckrl is resistant to ethylene and is allelic to the ethylene-resistant mutant ein2.The responses of seedlings to developmental and environmental cues have been useful in studying signal transduction pathways in plants. Arabidopsis thaliana seedlings respond to exogenously added or endogenous cytokinins, and in light-grown se...

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Synergistic effect of calcium and kinetin on ethylene production by the mungbean hypocotyl

Cited by 36 publications

References 9 publications

Cytokinin-Induced Ethylene Biosynthesis in Nonsenescing Cotton Leaves

Cytokinin-Induced Ethylene Biosynthesis in Nonsenescing Cotton Leaves

Interaction of Kinetin and Calcium in Relation to Their Effect on Stimulation of Ethylene Production

Cytokinin Action Is Coupled to Ethylene in Its Effects on the Inhibition of Root and Hypocotyl Elongation in Arabidopsis thaliana Seedlings

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