摘要:

Birch (Betula pendulaRoth.) was investigated under steady state nutrition and growth at different relative addition rates of phosphorus (Rp). Phosphorus deficiency symptoms appeared on the leaves when the internal phosphorus concentration decreased, but disappeared again under steady state nutrition, independent of the stress level. The increased root/shoot ratio and the exploratory type of root systems developed during the adjustment stage remained under steady state conditions. At nonoptimum and close to optimum relative addition rates, independent of the rate, the phosphorus concentration of the culture solution did not exceed 2 μmol dm−3and was generally<1 μmol dm−3immediately after phosphorus additions. The phosphorus concentration just before additions was generally<0.5 μmol dm−3. The nutrition/growth relationships were similar to those for nitrogen, with relative growth rate (Rg) closely related to the Rpapplied and with a strong linear relationship between internal phosphorus concentration and Rg. Regression was much steeper than that for nitrogen. The slope of the optimum nutrition was attained at a lower phosphorus weight proportion to nitrogen (8–10 P: 100 N) than previously estimated (= 13 P: 100 N), but a higher relative phosphorus requirement was observed under stress conditions. Birch seedlings had a strong tendency to consume phosphorus in excess of immediate requirements with a small effect on growth above optimum. This resulted in rapidly decreasing phosphorus productivity (Pp, growth rate per unit of phosphorus) with increasing internal phosphorus concentrations abo

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05827.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

NADH‐ferricyanide oxido‐reductase (EC 1,6,99,3) of purified plasma membrane vesicles isolated by aqueous two‐phase partition from segments of etiolated soybean [Glycine max(L.) Merr. cv. Williams] hypocotyls was used as a measure of plasma membrane redox activity. Elongation growth of hypocotyl segments floated on the solutions was determined in parallel.Cis‐platinum (II) diammine dichloride (cis‐platin), adriamycin andp‐nitrophenylacetate, agents known to inhibit cell proliferation and plasma membrane redox activities in mammalian cells inhibited both NADH‐ferricyanide oxido‐reductase of the isolated membrane vesicles and elongation growth of intact hypocotyl segments. Auxin(2,4‐dichlorophenoxyacetic acid)‐induced growth of the isolated segments was inhibited preferentially at drug concentrations where control growth was affected only slightly. The findings suggest a connection between plasma membrane redox reactions and the control of elongati

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05828.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Changes in chlorophyll fluorescence emission from maize (Zea maysL. cv. Northern Belle) seedlings chilled at 1.5°C in the dark for 3–30 h were compared with the ability of plants to resume growth in the immediate post‐chilling period and with the development of visible symptoms of injury to the leaves. During chilling, the maximal rate of increase of the induced chlorophyll fluorescence rise. FR, was measured on secondary leaf tissue. FRdecreased exponentially, at approximately the same rate in plants grown and chilled in hydroponic pots, in leaves detached from similar plants and in plants that were removed from the hydroponic pots and laid on wet filter paper adjacent to the detached leaves. The half‐fall time for FRin the 3 treatments was 7.8 ± 1.3 h, 8.6 ± 0.6 h and 8.8 ± 1.0 h, respectively. Following seedling removal from 1.5°C and return to 25/15°C, relative growth rates were determined from daily measurements of plant fresh weight gain. Compared with non‐chilled seedlings, plants chilled for 3 h and longer showed depressed rates of growth. Inhibition of growth in the immediate post‐chilling period (0–27 h) was linearly related to the duration of the chilling period and had a high positive correlation with the decrease in chlorophyll fluorescence (linearly related to log FR) sustained during the chilling exposure. Visible symptoms of chilling injury developed during the post‐chilling period on seedlings chilled for longer than 3 h. The decrease in log FRduring chilling was also linearly correlated with the severity of visual symptoms of chilling injury expressed in the post‐chilling period. It is concluded that the extent of chilling injury in maize can be rapidly and non‐destructively assessed from measurements of c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05829.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Embryos ofPicea abies(L.) Karst were pulse‐treated with water or cytokinin for 2 h and then cultured on medium lacking cytokinin. Adventitious buds developed on cytokinin‐treated embryos, but not on water‐treated embryos. The general appearance and the surface morphology were similar on water and BA (benzyladenine)‐treated embryos after 3 days. The epidermal cells were elongating after 6 days on water‐treated embryos, while they were dividing on cytokinin‐treated embryos. Furthermore, the cells surrounding the stomata had started to proliferate on BA‐treated embryos. This was the first micromorphological sign of bud initiation. During the second week prominent meristemoids developed from these cells. A stoma was observed on the top of each meristemoid. The variation in developmental pattern of meristemoids among different embryos as well as within each embryo was small. However, during the subsequent development of bud primordia and buds, the morphological variation was significant. The meristemoids continued to develop into cone‐shaped bud primordia, which successively changed shape during the transition to adventitious buds. The epidermal cells divided and the epidermis did not rupture during the formation of adventitious bud primordia. The epidermis was identified as the protoderm of the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05830.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

During the senescence of detached first leaves of oat (Avena sativaL. cv. Victory) seedlings (grown in continuous light) the protein is hydrolyzed and the proteases increase, but the expected simple relation between these two factors is not always realized. The present experiments examine the timing, the influence of light and darkness and the action of the protein synthesis inhibitors cycloheximide (CHI) and cordycepin. Transfer from dark to light delays the breakdown of both chlorophyll (Chl) and protein, but some residual proteolysis is ascribed to the enzyme initially present. Transfer to CHI resembles transfer to light, while the action of cordyceptin is similar but much weaker. Repeated determinations of the acid protease, which is the most active one and the first to appear, show that this enzyme is formed in the light about as rapidly as in the dark, though with different kinetics. In spite of this there is little proteolysis in light in the first 5 days. One possible explanation of that could be that protein is rapidly resynthesized in light, but treatment with [14C]‐leucine shows that such resynthesis is no faster in light than in darkness. It is therefore concluded that the protease initially does not have access to its substrates and, as a corollary, that the senescence process must be controlled by the gradual impairment of the vacuolar membrane, allowing protease to enter the cytosol and attack the proteins there and in the organelles. This concept is supported by many observations on the timing and on the known changes in membrane permeability during senescenc

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05831.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Crude mitochondria isolated from Jerusalem artichoke (Helianthus tuberosusL.) tubers were purified on a 23% (v/v) continuous Percoll gradient. Microbodies and damaged mitochondria banded on top of the gradient, whereas the purified mitochondria handed close to the bottom. The purified mitochondria showed improved membrane integrities, specific enzyme activities and respiratory properties (higher rate, respiratory control, ADP/O ratio) than the crude mitochondria. Purified mitochondria could he stored for 24 h on ice in a phosphate buffer with only small loss of activity.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05832.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Effects of different N/P ratios on several root parameters and on net P uptake were studied in winter wheat,Triticum aestivumcv. Starke II, grown in water culture. In the First experiment N/P ratios of (0/4, 2/3, 4/2, 6/1 and 8/0) were used, and plants were harvested at age 3, 5, 8, 11 and 14 days. In the second experiment N/P ratios of 6/1, 10/1, 15/1, 17/1, 20/1 and 25/1 were applied at two different N,P levels. Root length and number were determined using a digitizer connected to a computer. In the first experiment. the 6/1 N/P ratio gave the largest plants at day 14, and growth decreased with decreasing N/P ratio, The same pattern was found fur lateral root length and root number (seminal and lateral). In the second experiment the root weights decreased with increasing N/P ratio within each level. Lateral root number and overall length decreased with increasing N/P ratio at both levels as did the average lateral root length at the high N,P level. At the low N.P level, average lateral root length was about the same at all N/P ratios. Increasing the N/P ratio increased net uptake of P at the low N,P level, but decreased net P uptake at the high N,P level. Net P uptake increased with increasing P concentration in the roots and then decreased with further increase in P concentration. Net P uptake based on calculated root length [m (g root)−1] showed no significant deviation from weight‐based uptake plots. The effect of N and P on root structure is discussed as well as the interaction of N and P in P uptake. The relevance of a proper basis for expressing root activity is stres

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05833.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Plasmalemma‐rich microsomal vesicles were prepared from whole leaf and acid‐washed epidermal tissue ofVicia fabaL. cv. Osnabrücker Markt by aqueous two‐phase partitioning in dextran T‐500 and polyethylenglycol 1350 aqueous phases. These vesicles were tightly sealed and predominantly right‐side out, and contained a K+‐stimulated, mg2+‐dependent and vanadate‐sensitive ATPase. The enzyme from both tissues exhibited nearly identical properties: pH optimum 6.4,Kmfor ATP 0.60 mM(whole leaf) and 0.67 mM(epidermis). Vmax‐480 nmol (mg protein)1min1(whole leaf) and 510 nmol (mg protein)1min1(epidermis), I50(Na3,VO4) 7.5 μM(whole leaf) and 15 μM(epidermis). The enzyme was not inhibited by NO3(50 mM)or sodium azide (I mM). DCCD (20 μM) reduced enzyme activity to 50% (whole leaf) and 58% (epidermis), gramicidin S (20 μM) to 36% (whole leaf) and 41%(epidermis). Ca2+inhibited the ATPase [I50, C2+: 0.5 mM(whole leaf) and 0.8 mM(epidermis)]. Ca2+inhibited the ATPase [I50, C2+0.5 mM(whole leaf) und 0.8 (epidermis)]. The vanadate‐sensitive ATPase from whole leaf and epidermal tissue was slightly but significantly stimulated by fusicoccin (FC) at a concentration (0.13 μM) promoting stomatal opening. The stimulation was not seen in the solubilized ATPase. Stomata of the cultivar used here were insensitive lo (±)ABA up to 2 μMlevel which is effective in most other cultivars and species. Likewise, at this concentration no effect of ABA on the activity of the epidermal ATPase was observed. The data are discussed with respect to the interaction of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05834.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

The detergent Tween‐20 solubilized preferentially portions of the marginal regions ofSpinacea oleraceaL. thylakoid membranes and, thus, opened the inside of the grana to the external media. Differential centrifugation. following Tween‐20 solubilization. enabled separate fractions of grana and stromal‐exposed membranes to be isolated. Analysis of Tween‐20 solubilized material, after pelleting all membrane material by centrifugation at 100 000 g, revealed polypeptides associated with the coupling factor (CF1) particles, cytochrome b6/f and photosystem II complexes, suggesting that the marginal membranes contain these proteins. Concomitantly, the 100 000 g pellet was depleted in cytochrome b6/f and P700, determined spectroscopically, Thus. our results reveal the margin to be a distinct membrane region, which does not contain the light‐harvesting centers of photosystem II (LHC II). The implication of these results, in terms of the energetic interaction of components of granal and stromalexposed membrane regions, is

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05835.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Klotz, M. G. and Erdei, L. 1988. Effect of tentoxin on K+transport in winter wheat seedlings of different K+‐status.The influence of the phytoeffective mycotoxin, tentoxin, [cyclo‐(L‐leucyl‐N‐methyltrans‐dehydronhenyl‐alanyl‐glycyl‐N‐methyl‐L‐alanyl)] (in K+uptake and on translocation of K+from roots to shoot was studied in 14‐day‐old winter wheat plants (Triticum aestivumL. cv. Martonvásári‐8) grown at different levels of K+supply. For comparison, the effects of 2,4‐dinilrophcnol and valinomycin were also investigated. In I‐h experiments I pMtentoxin reduced K+influx in the routs over the external K+concentration range 0.1 to 1 mM(low‐K+plants), whereas stimulation was observed al lower and higher K+concentrations. On the other hand, in plants grown at 0.3 mMK+, tentoxin stimulated the translocation of K+from roots to shoots in 5‐h experiments. Valinomycin affected K+transport only al high K+‐status (slight stimulation). In low‐K+plants 2,4‐dinitrophenol (DNP) caused drastic inhibition of K+uptake, but in high‐K+plants uptake was only slightly inhibited and translocation slightly stimulated, It is concluded that the opposite effects of tentoxin on K+uptake and translocation agree1 with the directions of the H+‐ATPases pumping H+towards the apoplast and located at the cortex plasmalemma and the xylem parenchyma plasma‐membrane, respectively. These effects should probably be attributed to the interaction between tentoxin and the K+‐carrier protein rathe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1988.tb05836.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY