摘要:

Growth of the heterotrophic seedlings ofDactylorhiza majalis(Rchb.f.) Hunt&Summerh. (Orchidaceae) in vitro with a symbiotic fungus (Rhizoctoniasp.) is density‐dependent, even at densities that are not high enough to exploit the growth medium fully. Competition was two‐sided; increasing density among seedlings did not increase size inequality between them. The slowly growing and smaller seedlings are normally more likely to die than the bigger ones, but mortality was not increased by higher density within the studied range. Growth depression by neighbouring seedlings is independent of their physical distance but varies with the total number of seedlings sharing the same culture dish and the same mycelium.Therefore, if the growth‐promoting effects of different fungi or treatments are to be compared in future work, the density of planting in the culture dishes should be compa

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05379.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Cell wall proteins were extracted from maize coleoptiles,Zea maysL. B37 x MO 17, with high concentrations of LiCl. Ion‐exchange, chromatofocusing and gel‐filtration chromatography were employed extensively to purify exo‐β‐glucanase activity from the extract. The purified enzyme functioned as an exo‐(1→3)‐β‐glucanase (E.C. 3.2.1.58) and as a glucosidase (E.C. 3.2.1.21) capable of extensive hydrolysis of the nativeZeawall (1→3), (1→4)‐β‐d‐glucan, yielding glucose as the final product. The exoglucanase also enhances elongation of maize coleoptile sections in both the presence

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05380.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Coleoptile cell wall proteins fromZea maysL. hybrid B 37 × Mo 17 were extracted and fractionated. Three enzymes identified in that extract were examined to determine their role in cell wall hydrolysis with a goal of evaluating the extent to which they participated in autohydrolytic reactions. Two separate proteins were identified as endo‐ and exo‐glucanases. Incubation of these enzymes with heat inactivated cell walls, liberates products derived from the constitutive (1→3), (1→4)‐β‐d‐glucan. The release of sugars from walls resembles that of cell wall autolysis. A third cell wall protein degraded polysaccharides in a more general manner, releasing carbohydrates containing xylose, arabinose, galactose and glucose. Polyclonal antibodies raised against the exoglucanase protein suppressed autolytic reactions of iso

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05381.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Prolamellar bodies were isolated from dark‐grown leaves of 6.5‐day‐old wheat (Triticum aestivumL. cv. Walde). The prolamellar bodies were immobilized in agarose beads to get a material suitable for studies on pigment and protein release, and to protect the membranes from mechanical breakage. The beads were treated with detergents and salt solutions of different ionic strengths and the eluates collected. Protochlorophyllide in the eluate was determined by fluorescence spectroscopy. Dot‐blot tests were used to estimate the amount of released NADPH‐protochlorophyllide oxidoreductase (E.C. 1.6.99.1.). Changes in ultrastructure of the treated prolamellar bodies were analysed. Release of both membrane constituents increased by treatment with detergents. With 0.2% (w/v) Triton X‐100, 60% of the fluorescence from the immobilized prolamellar bodies was eluted within 30 min. Salt solutions with increasing ionic strength increased the release from 3 to 7%. The detergent treatment resulted in a complete (Triton X‐100) or partial ([3‐(3‐cholamidopropyl)‐dimethylammonio]‐1‐propanesulfonate, CHAPS; 1‐octyl β‐d‐glucopyranoside, octylglucoside) loss of the highly regular structure of the prolamellar bodies. Immunogold labelling of ultrathin sections revealed the absence of NADPH‐protochlorophyllide oxidoreductase when the regular structure was dissolved into single membranes. The regular appearance of the prolamellar bodies was altered by treatment with 0.1MCaCl3and 0.1MKSCN, respectively, but not with 0.1MKCl. Immunogold labelling showed that that enzyme was still present in the prolamellar bodies after these treatments. Despite the ultrastructural changes, the spectral properties were unchanged. Thus we conclude that NADPH‐protochlorophyllide oxidoreductase is firmly attached to the prolamellar body membranes and that the regular ultrastructure of the prolamellar body is partly c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05382.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Effect of gibberellic acid (GA3) on leaf sheath elongation in a normal (cv. Møystad) and a gibberellin(GA)‐insensitive (cv. Siete Cerros) genotype of wheat (Triticum aestivumL.) were studied at 18 and 12°C under short (SD, 12 h) or long (LD, 24 h) photoperiod. Leaf sheath length in cv. Møystad was signficantly increased by exogenous GA3both under SD and LD. LD alone stimulated leaf sheath elongation and the combined effect of LD and GA3was additive, and there was no statistically signficant interaction between photoperiod and GA3concentrations. Leaf sheath length in cv. Siete Cerros was not significantly affected by GA3under any conditions. However, there was a highly significant stimulation of leaf sheath elongation by LD in cv. Siete Cerros as well. These results indicate that stimulation of elongation growth in wheat leaves by LD is not mediated by gibbere

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05383.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abscisic acid (ABA) and wheat germ agglutinin content of immature wheat grains and embryos was determined by immunoassay throughout the development of a field‐grown wheat crop (Triticum aestivumcv. Timmo). Wheat germ agglutinin accumulation in the embryo was not preceded by an increase in endogenous abscisic acid amount or concentration in either embryos or grains. At a later stage in development the endogenous concentration of abscisic acid in both embryos and grains was found to be two orders of magnitude lower than the endogenous levels required to inhibit precocious germination and promote wheat germ agglutinin accumulation in excised embryos cultured in vitro. These findings are discussed in the context of the control of embryo development in vivo by both ABA and the water status of the grain and embry

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05384.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The possibility of modulating shoot growth charaeteristics of seedlings of two inbred lines ofPlantago majorL., differing in relative growth rate (RGR), by exogenously applied 6‐benzylaminopurine (BA), α‐naphthalene acetic acid (NAA), (gibberellic acid (GA3) and (2‐chloroethyl)‐trimethyl‐ammonium chloride (CCC) was investigated. BA completely inhibited growth of the shoot at a concentration of 1 mM, while lower concentrations had no effect. NAA reduced growth of the shoot at 10 üM, while 1 mMcompletely inhibited growth. Addition of 10 μMGA3or higher stimulated shoot fresh weight up to 20% and leaf area up to 30% for the slow growing inbred line (W9), but less for the fast growing line (A4). Application of 1 mMCCC, an inhibitor of gibberellin metabolism, reduced growth of both inbred lines, but to a larger extent in the fast growing seedlings.The lower shoot growth of W9 was associated with a lower specific leaf area (SLA) and a higher dry matter percentage of the shoot, as compared with A4. NAA reduced growth by reducing SLA and increasing leaf thickness, but the percentage dry matter of the leaves was unaffected. Stimulation of the shoot growth by GA3application was associated with higher SLA and lower dry matter percentage. Application of CCC had opposite effects on SLA and dry matter percentage as compared with GA3. GA seems to be involved in the regulation of at least part of the genetic difference in RGR inPl

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05385.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Germinated wheat seeds (Triticum aestivumL. cv. Barqai) that had been subjected to short hydrostatic pressure treatments (0.3–1.2 MPa) changed their normal metabolism into one which is characterized by a high ethanol production, a low O2consumption and a low CO2evolution. Alcoholic fermentation could account for ca half of the CO2evolved from the pressurized seeds. The level of acetaldehyde was low, though significantly higher in the pressurized seeds than in the controls. Subjection of wheat seeds to osmotic stress under aerobic conditions lowered their O2uptake and CO2evolution but did not induce ethanol production. Exposure of pressurized seeds to NaCl stress did not alter their ethanol production beyond that which had been induced by pressure. Ethanol production by pressurized seeds increased following either the addition of sucrose or by excision of the embryos from the endosperms. More electrolytes leaked into the embedding solution from pressurized seeds than from control seeds. Exogenous ethanol was toxic to wheat seeds at concentrations as low as 343 mM. The effects of hydrostatic pressure and of the consequently induced ethanol production on the mortality of flooded seeds is discusse

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05386.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Irradiation of cultured rose (Rosa damascenaMill. cv. Gloire de Guilan) cells with ultraviolet light caused of loss of K+, which occurred with sigmoid kinetics. The kinetics of loss of K+were not changed when the extracellular concentration of K+was held constant during the period of efflux. Furthermore, the rate of loss of K+was approximately the same even though the K+concentration in the medium was increased from 0.1 to 10 mM. The kinetics of uptake of the lipophilic methyltriphenylphosphonium cation, an indicator of the plasma membrane potential, were linear throughout the period of K+efflux, suggesting that the starting and stopping of K+efflux do not reflect a passive response to changes in the membrane potential of the cells. The results are interpreted in terms of activation and inactivation of an efflux channel or pump for K+.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05387.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Changes in ribosome population, RNA species and DNA composition in flower buds of apples (Malus pumilaMill. cvs Ralls and White winter pearmain) were investigated during breaking of dormancy and development. After bursting of flower buds, total ribosomes increased approximately 4‐fold, and the polyribosomal fraction increased from 66% to 94% of total ribosomes. The newly synthesized ribosomes were identified by incorporation of radioactive precursor. The observed decrease in specific radioactivity of the monoribosomes is caused by the recruitment of monoribo‐somes into polyribosomes after breaking of dormancy.In both cultivars, the 25S and 18S rRNA peaks increased to a high level on April 8. The peaks of low molecular weight RNA were apparently increased after initial swelling of the flower buds. The DNA of flower buds was separated into three bands by electrophoresis. The median band is the main band of nuclear DNAs. The ahead band and the slow‐moving band are satellite components of nuclear DNAs, and they obviously rose after initial swelling of the flower buds. On April 8, when the flower buds had opened, two other small DNA bands could be detected. These results suggest that the changes in level of different ribosome populations, RNA species and DNA composition are related to dormancy breaking development of apple flower

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05388.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY