摘要:

Ectomycorrhizal seedlings of Scots pine (Pinus sylvestrisL. cv.), inoculated with the fungusSuillus bovinus(L. ex Fr.) O. Kuntze, and non‐mycorrhizal controls were grown in growth units with a circulating culture solution. Steady‐state nutrition and constant relative growth rates were achieved by means of varied relative nutrient addition rates and free access of nutrients. Typical mycorrhizas always formed within a short period of time after inoculation. The nutrition/growth relationships were in principle similar to previous studies under steady‐state conditions: there were close linear relationships between relative addition rate, relative growth rate and internal nitrogen concentration, i.e. an equilibrium established between nutrients added and taken up. This occurred when infected and uninfected seedlings were grown separately. When grown together in the same growth unit, there are indications that the fungus influenced the exudation pattern of the uninfected seedlings. More carbon was thus provided to the unspecified microflora in the cultivation system, and it was able to grow and withhold nitrogen from the seedlings. The mycorrhizal infection did not increase the specific uptake capacity of the roots, and the fungus constituted a sink for carbon. However, the nitrogen productivity (growth rate per unit of nitrogen per unit of time) was similar for mycorrhizal and non‐mycorrhizal seedlings, so that there might be mechanisms which compensate for the carb

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03399.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The free space uptake and influx of Ni2+(63Ni2+) was characterized in excised roots of 7‐day‐old, dark‐grown barley (Hordeum vulgareL. cv. Møyar). Most of the Ni2+(63Ni2+) present in the roots after a typical experiment was removed by washing in CaCl2+, unlabelled NiCl2or EDTA solutions. The amount of loosely bound Ni2+increased during the first few minutes in the uptake solution, and then remained constant. A small fraction was tightly bound, probably mainly in the cell walls. Binding, both loose and tight, increased with concentration, as did influx. However, the lower the external Ni2+concentration, the larger was the proportion of Ni2+tightly bound compared with the total amount of Ni2+taken up. Ni2+influx was lowered by 85% with 2,4‐dinitrophenol, which may indicate that Ni2+is actively absorbed across the pla

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03400.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The effects of exogenous ornithine, arginine and polyamines added to media leading to root, callus or bud initiation ofDatura innoxiaMill. leaf explants growing in vitro were examined. Ornithine and arginine decarboxylase activities (ODC, EC 4.1.1.17; ADC, EC 4.1.1.19) as well as endogenous polyamine levels were also determined during the course of in vivo differentiation of the leaves and their subsequent in vitro dedifferentiation under rooting, callusing, or budding conditions. Decarboxylase activities were determined by measuring the14CO2released and the polyamines were quantified after dansylation by thin‐layer chromatography. In vivo, ODC and ADC activities decreased from shoots to young to old leaves. In vitro, synergistic effects between ornithine and indole‐3‐acetic acid on rhizogenesis were detected, while arginine was not effective. Exogenous putrescine also acted synergistically with auxin by promoting root growth. A close relationship was found between rhizogenesis, ODC activity and increase in endogenous putrescine and spermidine levels. ODC increased during the induction and time course of cell dedifferentiation and seemed to support these events, while ADC seemed to support only the later events involving redifferenti

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03401.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The very basal, highly immature regions of dissected young leaves ofTriticum aestivumL. cv. Kite formed adventitious roots on a nutrient medium supplemented with comparatively low concentrations (0.16 to 0.63 μM) of 2,4‐dichlorophenoxyacetic acid (2,4‐D). Higher concentrations (up to 640 μM) had to be applied to stimulate growth from more mature regions higher up the leaf. Yet, already at 2.5 μMroots were less distinct and more callus‐like, and eventually (at 10 to 640 μM) only a subculturable callus of apparently suppressed, slowly proliferating root primordia developed. Furthermore, at the most basal, highly immature regions growth was significantly retarded when the auxin concentration was raised. The leaf culture system appears to reflect the dual action of 2,4‐D known from herbicide research, namely growth stimulation from differentiating (or differentiated) cells, but growth suppression at or in the vicinity of apical meristems. Correspondingly, when the callus of apparently suppressed, slowly proliferating root primordia was transferred to media without 2,4‐D or with low concentrations (0.16–2.5 μM) rapid proliferation commenced, leading to profuse root outgrowth. The system demonstrates the ambiguous role which this auxin appears to have, at least in whea

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03402.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

We investigated the effect of 24‐epibrassinolide (BR) on the cytokinin‐bioassay based on growth of isolated radish (Raphanus sativusL. cv. Tondo Rosso Quarantino) cotyledons. BR stimulated growth of the cotyledons by about 50% when applied at saturating concentrations (3 μM). This effect was much lower than that of saturating concentrations of benzyladenine (BA) which was about 150% at 10 μMBA. The effects of saturating concentrations of BR and BA were additive. BR, but not BA, stimulated H+‐secretion by the cotyledons (measured as acidification of the incubation medium) slightly but reproducibly. These results indicate that the modes of action of the two phytoregulators are at least partially different.BR‐induced stimulation of H+‐secretion was of similar amplitude to that induced by a concentration of fusicoccin (30 nM) such as to stimulate growth to the same extent as BR. These results suggest that BR‐induced stimulation of radish cotyledon growth might depend, at least in part, on BR‐induced acidification of the wall space, similar to that observed on Azuki bean epicotyls

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03403.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Maize (Zea maysL., hybrid INRA 260) was grown in the greenhouse with mineral nutrition of different sulphate concentrations. Mature seeds from these plants were compared for their free amino acid and protein N forms. For the most S‐deficient sample, the Asx (asparagine + aspartic acid) content increased by 30% as compared with control, while methionine and cysteine decreased (by 25 and 30%, respectively), as well as glycine, lysine, histidine, arginine and tryptophan. In seeds lowest in S the non‐protein N to total N ratio was 77% higher than in the control. Free asparagine dominated in starved seeds (50 mol % of total free amino acids) and was ten‐fold more concentrated than in the control, where proline was the predominant free amino acid. Thus the Asx of non‐protein N reached 28% of the total mol Asx of the whole starved seed. Altered S nutrition had virtually no effect on the amino acid composition of the main protein fractions, but it significantly changed their ratios. Zeins, which are poor in S‐containing amino acids, showed 25% higher level than in seeds supplied with normal S. As a counterbalance, two glutelin subfractions rich in S‐containing amino acids, decreased by 36–71% under limiting S nutrition.It is concluded that the plant reacts against S deficiency by modifying its N metabolism. Significant accumulation occurred of free asparagine, which is the main form of N transportation. The biosynthesis of seed storage protein occurred through the accumulation of the highest possible protein quantity allowed by the available S‐containing amino acids, i.e. proteins low in S‐containing amino acids were preferent

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03404.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The distribution of nitrate reductase (NR, EC 1.6.6.1.) in the leaves of single‐stem tomato plants (Lycopersicon esculentumMill., cv. Vandenbergs Moneydor) was studied using an in vitro test. The activity decreased from young to old leaves. However, a low value (NR minimum) occurred in some leaves below the apex, usually in the almost completely expanded leaves, provided that the plants received sufficient nitrate to induce optimum NR activity in all the leaves. When insufficient nitrate was available there was NR in the young leaves only. The observed NR minimum coincided with a low value for soluble carbohydrates and amino acids. Since there was no extra export of labelled carbon from the leaves with the NR minimum, it is suggested that in the almost completely expanded leaves carbohydrates produced by photosynthesis are mainly used for the production of polysaccharides for new cell walls. Consequently, less are left for the production of keto acids, which can act as acceptors for reduced nitrogen. Therefore, less amino acids are produced, and this may result in a lowered protein synthesis, including a lowered synthesis of nitrate reductas

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03405.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Transverse electrical potentials were induced by 435.8 nm light, with lateral illumination of coleoptiles ofAvena sativaL. cv. Blenda. The potentials were recorded with the aid of the vibrating electrode technique, thus avoiding touching of the plants. The light dose was varied by changing the illumination time, the irradiance always being 3.9.10‐3W m‐2. The transverse potential varied in time after the start of illumination and the magnitude of it was dose‐dependent. Maximum voltages recorded were of the order of 15 mV, the illuminated side of the coleoptile then being negative with respect to the shaded side. Dose response curves were constructed and were very similar to dose response curves published in the literature for phototropic (blue light induced) curva

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03406.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

The effects of testa epidermal cracks on imbibition induced soybean (Glycine max[L.] Merr.) seed damage, as measured by the leakage of intracellular constituents, and on subsequent seedling survival were examined. Testa epidermal cracking increased with increasing seed surface area and this was caused by periods of dry seed hydration as short as 1 min followed by air drying. As compared to slow imbibition in germination paper, rapid imbibition of seeds caused by submersion in distilled H2O for 6 h at 25°C greatly increased the leakage of intracellular substances during imbibition and greatly decreased the survival of seeds with intact testae, testa epidermal cracks, and without testae. Seeds that were aerated during rapid hydration germinated as poorly and leached solutes as profusely as seeds not aerated. This indicates that anoxia is not a significant factor in rapid hydration effects on soybean seeds. Seeds with testa epidermal cracks had higher levels of leakage of intracellular substances and lower rates of seedling survival than seeds with intact testae. This was true regardless of rate of hydration. Testa tissues other than the epidermis had no effect on seedling survival after slow imbibition but greatly decreased seed leakage during rapid imbibition and increased subsequent survival. Studies with individual seeds indicated that the leakage of intracellular substances during rapid hydration is greatest from seeds that are killed or severely injured by imbibition or that are dead before imbibition, regardless of testa condition. These results indicate that soybean seed testa epidermis is extremely important in protecting the seed from injury by rapid and slow hydration and in maintaining seed viability

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03407.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY

摘要:

Long‐term effects of 1‐naphtaleneacetic acid (NAA), benzyladenine (BA), gibberellic acid (GA3), abscisic acid (ABA) and ethylene on K+levels, K+uptake and translocation to the shoot were studied in young wheat plants (Triticum aesticumL. cv. Martonvásári‐8) grown at different K+supplies. Na+levels and K+/Na+selectivity were also investigated. Both in shoots and roots, NAA, BA and ABA decreased K+and Na+levels more effectively in high‐K+plants than in low‐K+plants. GA, and ethylene did not influence K+and Na+levels. K+/Na+selectivity in roots of low‐K+plants was increased in favour of K+by BA, NAA and to a lesser extent by ABA. In high‐K+plants only BA increased the K+/Na+ratio, whereas the effects of the other hormones were the opposite (NAA) or less pronounced (ABA). K+(86Rb) uptake was inhibited by NAA and BA in low‐K+plants but not in high‐K+plants. K+(86Rb) uptake was inhibited throughout by 10 μMABA. K+(86Rb) translocation to the shoot was influenced by the hormones similarly to the uptake patterns, with the exception of ABA, which inhibited translocation in low‐K+plants but not in high‐K+plants. The results show that hormonal effects may quantitatively and qualitatively be modified by K+levels in the plant and that internal K+concentration may play a role in the mechanisms regulating the effects of NAA, BA and ABA but probably not in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1986.tb03408.x

出版商:Blackwell Publishing Ltd    

年代:1986

数据来源: WILEY