摘要:

Using high resolution ion‐exchange chromatography and isoelectric focusing the heterogeneity of the daffodil (Narcissussp.) lectin in terms of isolectin composition was analyzed. A survey of about 30 cultivars and species ofNarcissusdemonstrates (i) that they all contain over 50 different lectin polypeptides and (ii) that there are pronounced inter‐ and intraspecies differences in the isolectin patterns. Analyses of lectin preparations isolated from different tissues at different developmental stages further indicate that the isolectin composition is tissue specific and developmentally regulated. Finally, affinity chromatography experiments suggest differences in affinity for a mannose‐Sepharose 4B column of different isole

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05858.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Seasonal changes in several forms of nitrogen were investigated in the evergreen chamaephytePachysandra terminalisSieb. et Zucc. growing in temperate evergreen coniferous forest. After plants sprouted new shoots, nitrogen accumulated largely as proteins in the leaves from summer to late autumn and, additionally, during a short spring period in the following year. Proteins accumulated in the overwintered leaves decreased markedly in summer, indicating that they were used for new shoot growth. A similar change was found in Fraction 1 protein. This is consistent with the seasonal changes in photosynthetic capacity and carboxylation efficiency observed in previous studies. The allocation of nitrogen to Fraction 1 protein increased in the spring, presumably to utilize better the relatively high light intensity at the forest floor before leaf expansion of the understory deciduous plants. In contrast to protein nitrogen, soluble nitrogen was present largely in stems and rhizomes. Aspargine was the major component of the amino acid pool in all organs throughout the year, especially in stems in summer. Since asparagine has the highest N:C ratio (2N:4C), an amino acid pool dominated by asparagine is economic in the use of carbon and advantageous for the carbon‐limited environment of the forest understor

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05859.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Rates of net photosynthesis (A), transpiration (E) and leaf conductance to water vapour transfer (gH2O) were measured on leaves ofLupinus angustifoliusL. cv. Ritson's andL. cosentiniiGuss. cv. Eregulla throughout development and on flag leaves of wheat (Triticum aestivumL. cvs Gutha, Gamenya and Warigal) after full expansion. Plants were grown in large containers of soil, in a naturally‐lit, temperature controlled glasshouse. Throughout most of their life, lupin leaves had higher photosynthetic rates and leaf conductances than found for wheat. During leaf ageing in lupins, photosynthesis and conductance changed proportionately such that leaf intercellular CO2concentration was maintained relatively constant at about 200 ppm. Under continuously cloudy conditions, leaf conductance at midday of lupins and wheat was higher than at similar photon flux densities at other times of day on cloudless days. On cloudy days the relationship between gH2O and photon flux density in lupins was very different from that derived from diurnal measurements on clear days. The potentially low water use efficiency under cloud, evident as decreases in the A/gH2O ratio, was rarely realised in practise due to a reduction in leaf‐to‐air water vapour concentration difference on cloudy days. The possible reasons for the high conductance on cloudy days are disc

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05860.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Free amino acid concentrations in needles of drought‐stressed and shaded seedlings of ponderosa pine(Pinus ponderosa Dougl.ex Laws.) were analyzed to determine the influence of low irradiance on a biochemical response to drought stress. A convenient method was developed for separating and quantitating amino acids in needle extracts using derivatization with dansyl chloride and reversed‐phase high‐performance liquid chromatography (HPLC). Twenty‐one amino acids were separated on an Ultrasphere ODS CIS column and detected with a fluorescence spectrophotometer. As little as 10 pmol of each were detected with good peak separation and reproducible retention times. The results of HPLC analysis showed that drought and shading induced an increase in total amino acid concentrations in needles; shading had the greater effect. Arginine and proline concentrations increased most in needles of drought‐stressed seedlings and remained high in unshaded seedlings recovering from drought 48 h after rewatering. Arginine and glutamine increased most in the shaded seedlings, which did not survive severe drought. The large increase in arginine in both drought‐stressed and severely shaded seedlings suggests that sequestering and storage of ammonia are important when stress reduces carb

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05861.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The effect of NaCl salinity at concentrations of 43–173 mM in nutrient solution on net gas exchange of attached cowpea [Vigna unguiculata (L.) Walp cv. California Black‐eye No. 5 (CB5)] leaves was investigated under both greenhouse and growth chamber conditions.There was a marked decrease in leaf conductance to water vapor after exposure to low salinity levels and a slighter decrease when salinity levels were higher. The decrease in net assimilation was much more gradual throughout the entire salinity range. The altered responses of net assimilation and leaf conductance to salinity were more evident at a high light intensity. A decrease in intercellular partial CO2pressure [p(CO2)] was found at the low and intermediate salinity levels but not at the high level. These findings suggest that CO, assimilation was mainly controlled by stomatal conductance and the fixation of CO, might have been increased due to stimulated biochemical activity or to higher chlorophyll concentration per unit leaf area. A decrease in assimilation was already found one day after salinization and pro‐ceeded up to 4 days when it was inhibited by 50% at 43 mM NaCl and up to 85% at 173 mM. The decrease in transpiration was larger than the decrease in net assimila‐tion, and both were attributed to osmotic stress. Partial recovery was found thereaf‐ter and new steady‐state rates, in the range of 55 to 100% of the control, were then obtained for salinity levels between 43 and 130 mM. Inhibition of net CO, assimila‐tion at this stage was attributed partly to a specific sodium effect and partly to plant water status. A linear relationship between leaf sodium content and net photosynthe‐sis was also evident at this stage. Net CO, assimilation recovered more completely than transpiration when salt stress was removed, but at 173 mM NaCl recove

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05862.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Single‐node leaf‐bud cuttings ofSchefflera arboricolaHayata andStephanotis floribundaBrongn. were set and root formation, onset of axillary bud growth and plant height were measured. An increase in the number of roots in Schefflera, which was achieved with increasing cutting position on the stock plant (measured from top to base) or with increasing stem length below the node, accelerated the onset of axillary bud growth and resulted in an increase in plant height. Increasing the number of roots per cutting inStephanotisthrough an increase in basal temperature also accelerated bud and shoot growth. Positional effects on root formation inStephanotisshowed no relationship with axillary bud growth and plant height. A positive relationship between number of roots per cutting and axillary bud growth was found among clones ofStephanotis. In general the results suggest that, with some exceptions, the onset of axillary bud growth is accelerated in cuttings as a result of accelerated root formation and a higher number of roots per cutt

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05863.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The patterns of incorporation of [l‐14C]‐acetate into the glycerolipid fatty acids of leaves of olive plants (Olea europeaL. cv. Chétoui) suggested a specific pathway for a‐linolenic acid biosynthesis. The results confirmed the involvement of phosphati‐dylcholine in galactolipid metabolism, and seemed to exclude the role of that mole‐cule as a substrate for desaturation of oleate to linoleate. The two oleate desaturation steps seemed to occur rapidly on the diacylgalactosylglycerol molecule for biosynthesis of galactolipid linolenate. In addition, the results indicated a slow sequen‐tial desaturation of oleate to linolenate via linoleate in the phospholipid molecules (phosphatidylcholine, phosphatidylethanolamine and phosphati

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05864.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In three high‐latitude populations of red fescue 15 to 21 weeks of primary induction at 6°C/8 h short day (SD) conditions were required for optimum flowering in subsequent long days (LD) at 15 to 18°C. The optimum temperature for SD induction was 9°C, the critical temperature being 15°C. In two of the populations only marginal induction took place in LD at 6 and 9°C, in a third population from 69°30′N latitude induction was equally effective in SD and LD at these temperatures. After primary induction in SD a transition to LD was required for initiation of inflorescence primordia, 12 to 16 LD cycles (24 h) being required for full secondary induction at 18°C. Marginal LD secondary induction caused a high proportion of viviparous proliferation even in fully seminiferous populations. The populations varied also in morphological characters, highlighting the genetic and taxonomic variability within theF. ru

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05865.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Chlorella saccharophila can utilize the amino acids arginine, glutamate. ornithine and proline as sole sources of nitrogen for growth. By comparison C. autotrophica utilized only arginine and ornithine. Following osmotic shock of Chlorella autotrophica from 50 to 150% artificial seawater rapid synthesis of proline (the main osmoregulatory solute in this alga) occurred in cells grown on arginine or citrulline. However, little proline synthesis occurred in ornithine‐grown cells. Distribution of radiolabelled carbon from [14C]‐arginine assimilation following osmotic shock of C. autotrophica agrees with the following pathway of arginine utilization: arginine→citrulline→ornithine→glutamate semialdehyde→pyrroline‐5‐carboxylate→proline. These 4 steps are catalysed by arginine deiminase (EC 3.5.3.6), citrullinase (EC 3.5.1.20), ornithine transaminase (EC 2.6.1.13) and pyrroline‐5‐carboxylate reductase (EC 1.5.1.2), respectively. Of these 4 enzymes, only arginine deiminase and pyrroline‐5‐carboxylate reductase were detected in the crude extract of the 2 Chlorella species. Arginine deiminase did not require specific cations for optimal activity. The deimi‐nase showed maximal activity at pH 8.0 and followed Michaelis‐Menten kinetics with an apparent Kmfor L‐arginine of 0.085 mMfor theC. autotrophicaenzyme and 0.097 mMfor that of C.saccharophila.The activity of arginine deiminase was not influen‐ced by growing C.saccharophilaon arginine. Ornithine competitively inhibited arginine deiminase with an apparent K, of 2.4 mMfor theC. autotrophicaenzyme, and 3.8 mMfor that ofC. saccharophila. Arginine utilization byChlorellais discussed in re

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05866.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The nitrate reducing capacity of pure cultures ofCenococcum geophilum(Sow.) Ferd.&Winge,Paxillus involutes(Batsch: Fr.) Fr. (strains 1 and 2),Piloderma croceumErikss.&Hjortst.,Suillus variegatus(Fr.) O. Kuntze (strains 1 and 2) and an ectendomycorrhizal (E‐strain) fungus was measured using an in vivo nitrate reductase (EC 1.6.6.3) assay. Differences between species and strains were established. The nitrate concentration of the culture medium influenced the nitrate reductase activities of the E‐strain fungus and one strain ofS. variegatus.The nitrate reductase activity of certain species and strains was a function of nitrate concentration. Addition of ammonium to the growth medium did not have any significant effect on the in vivo or in vitro nitrate reductase activity. The in vivo nitrate reductase activity in the mycelia ofC. geophilumand the E‐strain fungus decreased during 28 day growth in modified Melin‐Norkrans medium. For mycelia ofPaxillus involutus, Piloderma croceumandS. variegatusgrown on agar the in vitro assays showed higher nitrate reductase activity than the in vivo

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1990.tb05867.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY