摘要:

AbstractMore “diffusible” auxin is received from nonsterile than from sterile corn coleoptile tips. An artificial reinfection of sterile coleoptiles with epiphytic, IAA‐producing bacteria strains does, a superinfection of nonsterile coleoptiles does not increase the auxin amount. The difference between sterile and nonsterile tips persists if diffusion from the coleoptile surface is excluded by covering the surface with a paraffin layer. The greater the distance from the apex, the higher becomes the superiority of nonsterile tips. An artificial bacterial contamination of the contact face between tip and receiver agar block, or addition of glucose and tryptophan to the agar block, do not influence the received auxin amount. Consequently the additional, bacteria‐produced auxin delivered by the nonsterile tip is not produced at the cut surface or in the agar but is present in the tissues of the coleopt

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06395.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractStem cuttings ofPopulus nigrawere treated with 10 and 100 mg/1 each of IAA., IBA, 2,4‐D and NAA at one month intervals and observations were recorded for the morphophysiological status of the branches, their starch content and their rooting response. — The first phase characterized by delayed, short and scarce roots and the high starch content of cuttings coincided with the onset of winter dormancy in November lasting through February. It was followed by a phase of vigorous rooting and low starch content of cuttings coinciding with the renovation of growth activity in February lasting through October, except in April and May when rooting was more or less completely nullified. — The poor rooting in winter was caused by low activity of hydrolyzing enzymes not mobilizing starch into soluble sugars; and profuse rooting during active growth period by high activity of hydrolyzing enzymes caused by endogenous auxin, resulting in mobilization of reserved food materials necessary for the initiation and development of roots. The low rooting in April and May is ascribed to the fact that bulk of the mobilized food was used up in the growth of sprouted branches leaving very little for rooting when these cuttings were planted. — The seasonal changes in the effectiveness of exogenously applied auxins also appear to be related with the level of endogenous auxin. In June endogenous auxin was high due to high meristematic activity, the exogenously applied auxins raising it to supra‐optimal levels that were inhibitory. On the other hand, in October exogenously applied auxins enhanced rooting by raising it to an optimal level as the production of endogenous auxin had been decreasing gradually due to lowering temperatures. — The results demonstrate that auxin effect on differential rooting with season in this plant is determined by the physio‐morphological status of the branches that govern the production of endogenous auxin and is mediated primarily through its effect on mobilization of reserve food materials caused by enhanced activity of hydro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06396.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractA mechanism is postulated to explain the immobility of boron in plants,i.e., the absence of any significant retranslocation of this element from one leaf to another. It is shown that boron readily enters the bark and is translocated within the bark. Since it has also been shown that boron remains water‐soluble in plants, the immobility cannot be explained through a chemical fixation, lack of entry into phloem, or absence of phloem transport. Rather, boron enters the phloem in leaf margins where concentrations are high, is transported in these conduits, is lost therefrom where the xylem concentration is low,i.e.in basal areas of the leaf and in petiole, is transported back in the xylem and accumulates in terminal place of the transpiration stream. A high local mobility of boron, together with the essentially unidirectional flow of the transpiration stream, thus cause a cyclic movement of B and prevent the efflux of this nutrient; this explains the immobility over long distance

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06397.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractAvena coleoptile sections were exposed to nonlethal concentrations of peroxyacetyl nitrate (PAN). The sections were then incubated in solutions of 50 mMglucose plus 2.5 mMpoassium phosphate with various concentrations of 2,4‐dichlorophenoxycetic acid (2,4‐D). Growth after 4 hours was measured. A corresponding series of experiments was carried out with glucose‐14C (U) in the subsequent incubation medium and the effect of the 2,4‐D treatments on14C incorporation into various cell wall components was determined. Growth in the PAN‐treated sections, although still partially inhibited, was greater at auxin levels normally superoptimal for growth than at the former optimum. Incorporation into all cell wall fractions was similar to growth in the case of control treated tissue. Most of the cell wall constituents, but particularly cellulose and less soluble noncellulosic polysaccharides, tended to show higher incorporation at the levels where PAN‐treated growth was also higher. It was concluded that effects by PAN on cell wall metabolism in growing tissue are similar to the effects on growth and that the mechanism of alleviation of growth inhibition is probably through decreased inhibition of wall

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06398.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effects of picloram (4‐amino 3,5,6‐trichloropicolinic acid) and several other chemicals on root permeability were studied. Initially, effects on cell permeability were investigated by measuring the betacyanin efflux from red beet (Beta vulgarisL.) root sections. Picloram solutions ranging from 10‐3Mto 10‐6Mhad no significant effect on betacyanin efflux when compared to controls. Similar results were found for 10‐4Mand 10‐5M2‐methoxy‐3,6‐dichlorobenzoic acid (dicamba), 10‐4M2,4‐dichlorophenoxyacetic acid (2,4‐D) and 10 μl/l of ethylene. Compounds that caused significant pigment leakage were 10‐4Mand 10‐5Mphenylmercuric acetate (PMA), 10‐3Mand 10‐4M2,4‐dinitrophenol (DNP), 10‐3Mand 10‐4M2,4,5–trichlorophenoxyacetic acid (2,4,5‐T) and 10‐3M2,4‐D.The effects of picloram on root permeability were also studied with bean plants (Phaseolus vulgarisL. cv. Black Valentine) grown in nutrient solution under controlled environmental conditions. Roots treated for 3 hours with 10‐5Mpicloram showed no significant electrolyte leakage as determined by conductivity measurements of the root‐bathing solution over a period of 52 hours. When bean plants were root‐trated for 3 hours with 10‐5M, and 10‐7Mpicloram and then decapitated, increased stem exudation by the treated plants as compared to controls was observed. Xylem exudate of the teated plants also showed increased electrolytic conductivity. The increased exudation rate accompanied by increased conductivity indicates that picloram has little effect on root cell membrane integrity, appears not to act as a metabolic inhibitor in the root system,

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06399.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractEthionine‐induced inhibition of elongation of Avena coleoptile segments has been measured in water and in indol‐3yl‐acetic acid. In the presence of 10 mML‐ethionine the inhibition amounts to about 70 %. It has been shown previously that the addition of adenosine triphosphate effectively counteracts this inhibition; optimal ATP concentrations are between 0.25 and 0.5 mM. Adenine, adenine sulfate, adenosine, guanine, S‐adenosylmethionine, and glutamic acid have now been shown to act similarly to ATP in reversing the ethionine‐induced inhibition of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06400.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractTylophora indicacallus tissue repeatedly subcultured every month on a series of different nutrient media in sequence regenerated roots, shoots and typical, bipolar embryosin vitrofrom unorganized callus parenchyma. The embryo‐like structures developed from somatic cells grew into normal plantlets when isolated and cultured on appropriate milieu of nutrients and hormones bypassing the normal sexual method of reproduction. Likewise, free cells in suspension also passed through embryonic stages reminiscent of development from fertilized eg

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06401.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe major ether‐soluble, growth‐stimulating substance detected by the Avena coleoptile straight‐growth test in extract from sprouting buds of Scots pine (Pinus silvestrisL.) was identified as indole‐3‐acetic acid by Rf values in 5 solvent systems and by its elution volume in ethanol on a Sephadex LH‐20 column. When the substance was applied to the growth solution of wheat roots in a special test the growth in length of the roots was at first inhibited, but growth was recovered after about 6 hours in the same manner as when small quantities of IAA were applied. The extracts also contained large amounts of growth inhibitors which interfered with the auxin response if they were

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06402.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractApical meristem culture ofEichhornia crassipeshas shown that for successful regeneration, the excised meristem dome must be associated with at least the youngest leaf primordium as part of the explant and a culture medium containing coconut milk (10 %, v/v), IAA (0.1 mg/l) and kinetin (1 mg/l) as growth supplements with 2 % sucrose as carbon source.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06403.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractRoot‐promoting substances were extracted from softwood cuttings ofSalix albaL. by centrifuging them with water or by shaking the ground freeze‐dried stems with water. Rooting substances were partitioned by paper chromatography or chemical fractionation and their rooting activity was tested by mung bean cuttings. Both extracts indicated three major root ‐promoting fractions at Rf 0‐0.1, 0.7‐0.8, and 0.3‐0.4 in a decreasing order of their activities when paper chromatographed with isopropanol:ammonia:water 8:1:1 v/v. The strongest one indicated an apparent synergistic rooting effect with indol‐3yl‐acetic acid (IAA) regardless of the extraction method. These results indicate that water can extract from freeze ‐dried sample the similar rooting substances found in the centrifugal diffusates. The Rf 0–0.1 fraction consisted of at least four fractions and the strongest one did not move from the starting line on the chromatogram when isopropanol:ammonia:water 8:1:1 was used. This starting line fraction was extremely strong in rooting activity and its highest concentration resulted in 8.7 times as many roots as controls. More thain additive rooting effect between IAA and the fraction was found only at the highest concentration. The fraction was very soluble in water but insoluble in chloroform or ethyl ether and only stimulated rooting of mung bean cuttings when it was applied within 3 days after cuttings were made. It had no effect in lengthening roots. The starting line fraction was further found to have four root‐promoting subfractions at Rf 0.05, 0.35, 0.65, and 0.85 when it was chromatographed in 60 % isopropanol. Among these four, the subfractions at Rf 0.65 and 0.35 were strongly root promotive and displayed more than additive root promotion with IAA at the highest c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1970.tb06404.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY