Transport in the Xylem

Bollard, E. G.

doi:10.1146/annurev.pp.11.060160.001041

Cited by 248 publications

(85 citation statements)

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“…Ca2+ is relatively immobile in cells (4), possibly because it has a high affinity for cell wall materials (25). During the course of 45Ca2+ uptake studies, we found that 45Ca2+ was readily extracted from the tissue homogenate by HCI (10-20 mM), but not by ethyl alcohol or H20.…”

Section: Methodsmentioning

confidence: 88%

Stimulation of Ethylene Production in the Mung Bean Hypocotyls by Cupric Ion, Calcium Ion, and Kinetin

Lau¹,

Yang²

1976

Plant Physiol.

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The synergistic stimulation of ethylene production by kinetin and Ca2l in hypocotyl segments of mung bean (Phaseolus aureus Roxb.) seedling was further studied. The requirement for Ca2l in this system was specific. Except for Sr", which mimicked the effect of Ca2", none of the following divalent cations, including Ba2+, Mg6", Cu2l, Hg2+, Co2+, Ni2+, Sn2+, and Zn2+, showed synergism with kinetin on ethylene production. Fe2+, however, showed a slight synergism with kinetin. Some of them (Hg2+, Co2l, and Ni2+) had a strong inhibitory effect, while others (Zn2+, Mg2+, Sn2+, and Ba2l) had a slight or no inhibitory effect on ethylene production in the absence or presence of kinetin.Cu2+ alone, depending on the concentration applied, stimulated ethylene production with a lag period of about 2 hours and had no synergism with kinetin on ethylene production. When Cu2+ was applied with Ca2l, a remarkable synergistic stimulation of ethylene production was observed.Tracer experiments indicated that Cu2l enhanced the uptake of 45Ca2+ into the tissues during the first few hours of incubation, and this increase of 45Ca2+ uptake paralleled the enhancement of ethylene production. When Ca2+ was applied together with kinetin plus Cu2+, both the ethylene production and the 45Ca2+ uptake were greatly increased over those from the segments treated with Cu2l or kinetin alone. The increase in ethylene production as a result of kinetin plus Ca2l plus Cu2+ treatment is equal to the combined increases caused by kinetin plus Ca2l and Cu2l plus Ca2l. A possible mechanism accounting for such cooperative effects of Cu2+, Ca2l, and kinetin 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 I cm below the hook, as previously described (14). Lots of 20 segments were incubated in 5 ml of a medium consisting of 50 mm potassium phosphate buffer, pH 6, 2% sucrose, various concentrations of different divalent cations, kinetin, or labeled 45Ca2+ (100 ,uCi, 50 ,umoles) as indicated, in a 50-mi Erlenmeyer flask. A plastic center well containing 0.2 ml of 40% KOH was hung in the flask to absorb CO2 evolved. The flasks were sealed with rubber serum caps and incubated in a shaker at 27 C in darkness.At time intervals indicated, 1-ml gas samples were withdrawn by hypodermic syringe, and ethylene was assayed with a gas chromatograph equipped with an alumina column and a flame ionization detector. The flasks were flushed with air and recapped for the next ethylene determination.For 45Ca2+ uptake studies, the hypocotyls, incubated for a given time interval, were washed with 10 changes of distilled H20, and then ground with a glass homogenizer in 9 ml of 80% ethyl alcohol. The debris was pelleted by centrifugation, and the supernatant was collected. The pellet was serially extracted three times with 5 ml of 20 mm HCI. The radioactivity in each extract and in the debris was determined with a ...

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Section: Methodsmentioning

confidence: 88%

Stimulation of Ethylene Production in the Mung Bean Hypocotyls by Cupric Ion, Calcium Ion, and Kinetin

Lau¹,

Yang²

1976

Plant Physiol.

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“…The experiments have been carried out wxiih numerous tree species of various size, in Prospect Hill (1). This corresponds to a freezing-point depression of not more than 0.20.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Low Temperature on Ascent of Sap in Trees

Zimmermann

1964

Plant Physiol.

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“…between 0-8 hr, Fig. 6), probably by interchange between xylem and phloem (Bollard 1960). Because of the high chloride concentrations already in the leaf cells of the developed organs, their ion uptake is likely to be slow (Briggs, Hope, and Robertson 1961) and retranslocation of recently arrived chloride might, therefore, be rapid.…”

Section: Chloridementioning

confidence: 99%

Plant Response to Saline Substrates V. Chloride Regulation in the Individual Organs of Hordeum Vulgare During Treatment with Sodium Chloride

Greenway¹,

Gunn²,

Pitman³

et al. 1965

Aust. Jnl. Of Bio. Sci.

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SummaryThis is a study on the regulation of chloride concentrations in H. vulgare at the early tillering stage, when grown on media of high sodium chloride concentration. 36CI was used during certain periods to determine retranslocation.Chloride, which had been absorbed either during the first 5 days, or between the fifth and tenth day of sodium chloride treatment, was not lost from the whole plant during subsequent periods, and this chloride moved to the shoot. Over the same period there was further chloride uptake from the medium.Developed leaves lost only small amounts of chloride by retranslocation and the concurrent intake far exceeded this loss. Evidence is presented that low concentrations in younger leaves are due to low mobility of chloride already taken up by older organs of the shoot, and not to a chloride exclusion by younger organs.It is concluded that chloride contents within the shoot of H. vulgare are regulated at two locations:(1) During transfer from the root to the shoot.(2) During translocation from older to younger organs.In growing organs, ion concentrations depend not only on the rates of ion uptake but also on relative growth rates, i.e. ion concentrations at anyone time are higher at low than at high relative growth rates.This interaction between growth and ion concentration is discussed in relation to ion imbalance, osmotic adjustments, and salt tolerance.

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Transport in the Xylem

Cited by 248 publications

References 0 publications

Stimulation of Ethylene Production in the Mung Bean Hypocotyls by Cupric Ion, Calcium Ion, and Kinetin

Stimulation of Ethylene Production in the Mung Bean Hypocotyls by Cupric Ion, Calcium Ion, and Kinetin

The Effect of Low Temperature on Ascent of Sap in Trees

Plant Response to Saline Substrates V. Chloride Regulation in the Individual Organs of Hordeum Vulgare During Treatment with Sodium Chloride

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