摘要:

Birch (Betula pendulaRoth.) was investigated under steady‐state nutrition and growth at different incident photon flux densities (PFD) and different relative addition rates of nitrogen. PFD had a strong influence on the relative growth rate at optimum nutrition and on the nitrogen productivity (growth rate per unit of nitrogen) but little effect on the formal relationships between nitrogen and growth, i.e. PFD and nitrogen nutrition are orthogonal growth factors. At a given suboptimum nitrogen (the same distance from optimum), increased PFD increased the relative growth rate and, therefore, the relative uptake rate and the required relative addition rate in accordance with the theoretical equality between these three parameters at steady‐state nutrition. Correspondingly, at a given suboptimum relative addition rate, increased PFD decreased nitrogen status (larger distance from optimum) at an unchanged relative growth rate. Nutrient uptake rate, dry matter content, and partitioning of biomass and nutrients are strongly influenced by nitrogen status. PFD influences these characteristics, but only to an extent corresponding to its effect on the nitrogen status. The influence of PDF on the relative growth rate at optimum and on nitrogen productivity is well described by hyperbolic relationships, similar to reported PFD/photosynthesis relationships. These expressions for plant growth as well as the productivities of leaf area and quantum appear to be valuable characteristics of plant responses to light and nutrition. Although the calculated PFD/growth relationships indicate saturation at high values of PFD, a more realistic estimate of PFD at which saturation occurs is about 30 mol m−2day−1, where the highest relative growth rate and nitrogen productivity were experimentally determined. No significant effect was observed because of day length differences between the present and previous expe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05970.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

We have estimated the amount of inside‐out plasma membrane (PM) vesicles in microsomal fractions from wheat (Triticum aestivumL. cv. Drabant) and maize (Zea maysL.) roots; non‐latent activities of the PM markers vanadate‐inhibited K+, Mg2+‐ATPase (ΔVO4‐ATPase) and glucan synthase II (GS II, EC 2.4.1.34) were used as markers for inside‐out PM vesicles, latent activities as markers for right‐side‐out PM vesicles, and specific staining with silicotungstic acid (STA) as a general marker for the PM. Separation of presumptive inside‐out PM vesicles from right‐side‐out ones was achieved by counter‐current‐distribution (CCD) in an aqueous polymer two‐phase system. Most of the GS II activity was latent and was found in material partitioning into the upper phase; a distribution which correlated well with that of STA‐stained vesicles. Thus, most of the PM vesicles had a right‐side‐out orientation. ΔVO4‐ATPase, on the other hand, had a dual distribution (particularly pronounced in wheat) and was recovered both in material partitioning into the lower phase and into the upper phase. This indicates that ΔVO4‐ATPase activity was present also in membranes other than the PM. Additional evidence for this interpretation came from sucrose gradient centrifugation of wheat root material. This produced two peaks of ΔVO4‐ATPase activity with the membranes partitioning into the lower phase, none of which coincided with the peak obtained with right‐side‐out PM vesicles. Taken together, these results indicate that only very few inside‐out PM vesicles are present in the microsomal fraction, and that ΔVO4‐ATPase as a marker for the PM, in contrast to GS II, may give quite misleading results with some plant materials. This stresses the need to use well‐defined preparations of scaled, inside‐out PM vesicles in solute uptake studies. The distribution of Ca2+‐inhibited ATPase, on the other hand, agreed well with those of GS II and STA‐stained vesicles both after CCD and sucrose gradient centrifugation, which suggests that Ca2+inhibition may be a more sp

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05971.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Cell wall lytic activity was detected inChlorella ellipsoideaGernick IAM C‐27 using the [14C]‐labeled cell wall as substrate. The highest activity was obtained at pH 8. and the solubilized product was a polysaccharide of high molecular weight. The lytic activity appeared to be a protease and did not hydrolyse glycosidic bonds of the cell wall polysaccharides. The activity probably solubilizes the cell wall by cleaving the peptide bonds that interconnect the polysaccharides of the cell w

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05972.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Protoplasts ofVitis rotundifoliaMichx. cv. Summit were isolated from mesophyll of axenic shoot cultures under different enzyme concentrations and digestion times. Viability and plating efficiency were assessed and related to the cortical microtubule network, visualized using immunofluorescence. Higher concentrations of enzyme isolation medium significantly decreased protoplast viability and plating efficiency. However, the cortical microtubule network appeared stable, at all concentrations with dense, continuous microtubule strands in both random and parallel arrays. In contrast, longer vs shorter enzyme incubation duration resulted in significantly lower plating efficiency, which was correlated with changes in cortical microtubule organization. With longer incubation, the frequency of parallel microtubule strands decreased; microtubule organization showed increasing disruption, microtubule strands were shortened, fragmented and exhibited only a weak fluorescence labeling. Both high enzyme concentration and prolonged incubation periods negatively affected protoplast regenerability, but in different ways. Microtubule organization was sensitive to duration of incubation, but not to enzyme concentration. It is concluded that the presence of a well‐developed cortical microtubule network does not gurantee regeneration. Other factors related to isolation appear to be involve

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05973.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Uptake of dissolved inorganic carbon (DIC) from a nutrient solution by willow roots was measured in light and darkness and the distribution in the plant of DIC taken up by the roots was determined. It was also studied whether the transport system could be activated by preincubation with dissolved inorganic carbon.Willow plants (Salixcv. Aquatica gigantea) grown in hydroponic culture media were preincubated for 2 days with or without 0.74 mM NaHCO3. After preincubation, either unlabelled or [14C]‐labelled NaHCO3was injected into the media and after 1, 5, 10 and 24 h either in light or in darkness the plants were harvested in pieces into liquid nitrogen, lyophilized and burned in a combustion chamber.14C was transported through the roots to the shoots and leaves both in light and in darkness, although incorporation of14C in darkness was only half of that in light at the end of the 24‐h feeding period. Both in light and in darkness the amount of14C increased in all parts of willow plants with time. In light the rate of labelling was highest into cuttings and shoots. In darkness more than half of the total label was detected in cuttings of both the non‐activated and the activated treatments.In the shoots the middle part was most strongly labelled after 5 and 10 h, but after 24 h14C moved towards the base of the shoot. In the leaves at all feeding times most radioactivity was incorporated into the young, fully open leaves on the upper part of the shoots. Preincubation of plants with unlabelled NaHCO3in growth media had no clear effect on the rate of DIC uptake either in light or in dar

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05974.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A mixture of tritiated and deuterated gibberellins (GAs) was injected into elongating shoots of Sitka spruce [Picea sitchensis(Bong.) Carr.] grafts grown under environmental conditions that were either inductive (heat and drought, HD) or non‐inductive (cool and wet, CW) for flowering. The metabolites were purified by high performance liquid chromatography (HPLC), detected by liquid scintillation counting of aliquots of collected fractions and identified by gas chromatography–mass spectrometry (GC‐MS). Deuterated GA9was converted to deuterated GA4, deuterated GA34, and deuterated GA1in both treatments. Deuterated GA4was metabolized to deuterated GA34and deuterated GA1in the CW material, but only deuterated GA1was detected in the HD material. The amount of detected metabolites was higher in the HD material, caused by a higher rate of metabolism and/or smaller losses of the metabolites during sample purification. GA1was converted to a polar unidentified metabolite in both treatments, but to a higher degree in the CW trea

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05975.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The effect of nitrogen on excretion and metabolism of glycolate inAnabaena cylindrica(CCAP 1403/2a) was studied. Glycidate, an inhibitor of glutamate:glyoxylate aminotransferase (EC 2.6.1.4), reduced the L‐methionine‐DL‐sulfoximine‐induced NH4+release by ca 40%, while net CO2fixation and C2H2reduction were not lowered. This indicates that at least a part of the glyoxylate synthesized inA. cylindricais metabolized via glycine to serine. Addition of NH4Cl or glutamate to the medium reduced the excretion of glycolate. At pH 9, under air, NH4Cl reduced the excretion by 10–30% and under high pO2 (0.03 kPa CO2in O2) by about 80–90%. At pH 7.5, under high pO2, NH4Cl and glulamate reduced the excretion by about 40 and 80%, respectively. Also, the presence of NH4Cl stimulated the animation of glyoxylate under such conditions as shown by an increased glycine pool and a decreased glutamate pool. We suggest that nitrogen regulates the capacity ofA. cylindricato retain and recycle glycolate intracellularly and that glutamate serves as an amino donor in the conversion of glyoxylate

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05976.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Detached ears of three winter wheat (Triticum aestivumL.) varieties were cultured in solution for 12 days with sucrose levels varying from 36.5 to 292mM. The dry weight and starch content of grains increased asymptotically with the sucrose level in the solution. At 4 days of culture, glucose phosphate isomerase (EC 5.3.1.9) activity grain−1was lower with 36.5mM than with higher sucrose levels in the medium; at 8 days, adenosinc diphosphoglucose pyrophosphorylase (EC 2.7.7.27) and (soluble plus bound) starch synthase (EC 2.4.1.21) activities grain−1were higher with 146 and 292mM sucrose than with 36.5 and 73mM sucrose. The multiple regression of starch content over these enzyme activities showed that starch synthase was relatively more important as an independent variable. The dry weight and starch content of grains were higher in the variety Maris Huntsman than in Splendeur and Hobbit. The water content of grains was lower in Splendeur than in the other two varieties. At 4 days the glucose phosphate isomerase, adenosine diphosphoglucose pyrophosphorylase and starch synthase activities grain−1were smaller in Splendeur than in Hobbit and Maris Huntsman and al 8 days they were higher in Maris Huntsman than in Hobbit and Splendeur. The varietal differences in starch content of grains were related to the activities of glucose phosphate isomerase and especially of starch syn

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05977.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Stem elongation growth in a slender line ofPisum sativumL. was much greater than in its two dwarf parental lines due to a greater rate of production of longer internodes. The cellular basis of the greater length of slender internodes was tissue specific. In the epidermis, greater cell length primarily accounted for the longer internodes of the slender plants, but in the outer cortex, greater cell number was the more important factor. The soluble and salt‐extractable peroxidase (EC 1.11.1.7) activities of expanding internodes were much lower in slender plants than in dwarf plants. The proportional effects of ethylene treatment on epicotyl length, diameter and orientation were similar in etiolated slender and dwarf seedling

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05978.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Leafy spurge (Euphorbia esulaL.), a serious perennial weed of temperature range and pasture lands, has continued to colonize despite various control strategies. The persistence of this species can be attributed in part to the presence of an extensive root system containing abundant organic reserves. These components, established towards the end of the growing season, are remobilized to support early spring growth. Carbohydrates comprise the bulk of reserve material with late fall incrents in free sugars being associated with reductions in starch content. Nitrogenous components undergo significant seasonal fluxes, with free amino acids and soluble proteins reaching maxima during late fall. Asparagine, glutamic acid, serine, ornithine, proline, arginine and aspartic acid all contribute significantly to the storage of nitrogen. Changes in nitrate content are associated with the overwintering process. These observations are indicative of the role that nitrogen plays in the overwintering strategy and regenerative capacity of leafy spurge roots.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05979.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY