Auxin Polarity in the Coleus Plant

Leopold, A. C.; Guernsey, Frances S.

doi:10.1086/335808

Cited by 66 publications

(10 citation statements)

References 7 publications

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“…The data presented here indicate that the effect of ethylene on the distribution of absorbed auxin is com- (16,18) are of interest to the present study because of the known increase in ethylene production with aging of tissue (10) and the finding here of an ethylene-induced decline in polar auxin transport. These observations suggest that ethylene in vivo may function in the control of auxin transport and thus as a senescence hormone.…”

Section: Discussionmentioning

confidence: 65%

Effects of Ethylene on Auxin Transport

1966

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Summary. The effect of ethylene on the uptake, distribution and polar transport of Cl4 from indole-3-acetic acid-2-C'4 and naphthalene acetic acid-i-C'4 in tissue sections was studied. Test species were cotton (Gossypiumn hirsutumit, L.) and cowpea (Vignla sinlellsis, Endl.). Generally, incubation of tissue or initact plants with ethylenie reduced the degree of polar auxin transport. Ethylene inhibited the movemiient of both auxins in stem tissue and IAA in petiole tissue of cotton. The effect of ethylene onl auxini mlovemelnt in cowpeas was more complex. Ethylene apparently inihibited transport in younlger petiole and stem tissue, but stimulated the process to a small but significant degree in basal petiole segments.Ethylene, in some experiments, reduced C14 (auxini) uptake. This reductioni was consistently smaller than the inhibition of transport. Effects upoll transport were observed when uptake was not different. Differenices in upltake declined as the period of inicubation with auxin was lengthened. but transport was inihibited for up to 23 hours.It is proposed that ethylemie may, through its effect on transport, cause localized shortages amid surpluses of auxiin whichi in tturn contrihute to symptonis now associate(l with the responise of senisitive species to ethylene.

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Section: Discussionmentioning

confidence: 65%

Effects of Ethylene on Auxin Transport

1966

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“…It is of interest to note that this difference does not increase with time as it does with larger volumes of solution (40 ml), higher IAA concentrations (1 mg/l), no buffer and no presoaking as used by Schneider (29). In the case of first internodes, growth seems to be completed after 18 hours (with low concentrations of IAA); if the sections are kept longer in the solutions, the controls grow more and more as time goes on, thus reducing the difference GIAA -G0 In consequence, if one wants to measure the IAA effect, at concentrations similar to those used here, one does not have to keep the sections in the solutions more than 20 hours. If one wants to measure inhibitors in relation to the controls without auxin, then the longer one waits, the larger will be the difference, because the controls will go on elongating for about two days.…”

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confidence: 99%

Studies on the Growth of Coleoptile and First Internode Sections. A New, Sensitive, Straight-Growth Test for Auxins

1956

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“…2). The response was also subsensitive in the slit pea test in data of Leopold andKlein (1952) -cf. Tab.…”

Section: Resultsmentioning

confidence: 93%

Dose responses of auxins

Nissen

1985

Physiologia Plantarum

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Published data for the most widely used bioassays for auxins as. well as other auxin‐induced responses, have been analyzed to determine whether the response is ultrasensitive, hyperbolic or subsensitive, i.e. whether the change from 10 to 90% of maximal response requires less than, equal to or more than an 81‐fold increase in external auxin concentration. Auxin‐dependent callus growth is most often ultrasensitive. Other responses, including the curvature of Avena coleoptiles, may show simple Mi‐chaelis‐Menten kinetics. In the majority of cases, however, the response is sub‐sensitive, often very markedly so. The finding of subsensitive responses is consistent with the proposal by A. J. Trewavas that plant development is regulated by changes in the sensitivity to plant growth substances. Detailed data for subsensitive dose responses, particularly auxin‐induced inhibition of root growth, can often be precisely represented by bi‐ or multiphasic isotherms, with the phases separated by sharp transitions. The relationship to auxin uptake and the relationship, if any, between carriers and receptors for auxins remain to be elucidated.

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Auxin Polarity in the Coleus Plant

Cited by 66 publications

References 7 publications

Effects of Ethylene on Auxin Transport

Effects of Ethylene on Auxin Transport

Studies on the Growth of Coleoptile and First Internode Sections. A New, Sensitive, Straight-Growth Test for Auxins

Dose responses of auxins

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