Rapid Growth Responses of Avena Coleoptile Segments to Lanthanum and Other Cations

Abstract

The rapid growth responses of oat (var. Victory) coleoptile segments treated with mr concentrations of the chlorides of La3+, Ca2+, K , and NH4+, respectively, have been measured. La`+ and Ca2+ initially depressed the endogenous elongation rate. In the case of La3+ a loknged stimulatory effect on the rate of elongation was produced by concentrations of 50 miflimolar down to 20 micromolar after an initial depression of elongation rate. The effect of K+ was slightiy stimulatory and showed a synergistic effect in combination with La3+. NH4+ produced an immediate rapid increase in elongation rate. La+ did not behave as a "super calcium" in its action upon the spontaneous growth response. The prolonged elongation of the LaU3-treated segments exhibiting the spontaneous growth response is apparently a newly observed effect. These rapid growth responses are interpreted as an interaction between anionic lipi-protein complexes in the plasmalemma and the respective ions. (8,27). MATERIALS AND METHODSUniform coleoptiles of A vena sativa L. var. Victory were grown as previously described (27). The seed oats were obtained from Svalof, Sweden. The harvest, cutting, and mounting of the coleoptile segments were conducted in dim green light. A 1-cm segment was cut 3 to 4 mm from the tip of each coleoptile. The coleoptiles were selected in pairs to ensure the greatest possible uniformity of biological material. Five of the segments, one ofeach pair selected, were threaded on a 0.30-mm-diameter plastic monofilament. Each of the filaments was placed in a high resolution growth-recording device similar to those described by Evans and Ray (7)

The influence of rare earth element fertilizer application on the distribution and bioaccumulation of rare earth elements in plants under field conditions

“…Zhu et al (1987) suggested that at low levels, REEs acted as nutrient with toxicity occurring at high concentrations. Other studies indicated that lanthanum caused rapid growth responses in Avena Coleoptil segment (Harmet, 1979).…”

Uptake and distribution of rare earth elements in rice seeds cultured in fertilizer solution of rare earth elements

“…Developed roots have a strong adsorptivity and encourage plant organs which are e ectively growing well above ground to attain high productivity. Many researchers (Harmet, 1979;Hanzely and Harmet, 1982;Guo et al, 1988;Gao, 1997) reported that REEs could stimulate the growth and development of plants, especially in plant roots. The above results demonstrated that the roots of rice could accumulate a much higher REE concentration than in the germs and the resting seeds, which is consistent with the literature (Li et al, 1998).…”

“…Nagahashi et al (1974) pointed out that Casparian strip acted as a barrier to the movement of lanthanum in the corn root. The rapid growth responses of oats treated with La 3 , Ca 2 , K and NH 4 were measured and it was found that La did not behave like super calcium in its action upon the spontaneous growth response (Harmet, 1979). The series interactions of trivalent lanthanide cations with the thylakoid membrane surface of spinach chloroplasts veri®ed that the added lanthanide cations were adsorbed onto the membrane surface to neutralize exposed segments of the membrane-embedded protein complex (Karukstis et al, 1995).…”

The role of calcium in exocytosis and endocytosis in plant cells

“…A consequence of the demand for calcium entry at secretory sites and calcium exit to tnaintain low cytoplasmic levels is that some circulation of calcium in the apoplast is to be expected. Expanding eells may well be net importers of ealeium (Harmet 1979, Moll and Jones 1981, Cunninghatne and Hall 1986. Cytochalasin inhibition occurs only after some auxin-induced elonga-tion has occurred (Cunninghame and Hall 1986, C. Preshaw and M. W. Steer unpubhshed data), suggesting that the initial elongation is independent of secretion.…”