bluuebunny/crossref_metadata_2025 huggingface dataset:
Partial characterization of a major family of proteins in turions of Hydrilla verticillata
Authors: Ryan Frederick J.
Published: May 2006

Electrophoretograms of turions of dioecious Hydrilla verticillata (L. f.) Royle, run under non‐denaturing conditions, had a major complex protein band at Rf0.45 (7.5% acrylamide). Extracts of monoecious plants under similar conditions had major bands at Rf 0.43 and 0.45. The polypeptides which comprise these bands were partially purified and characterized. The major protein fraction in extracts of dioecious turions had a molecular mass of 58 kDa on gel permeation chromatography. Electrophoresis of this fraction under denaturing conditions in the presence of sodium dodecyl sulfate indicated principal bands with molecular masses of 58 and 57 kDa. Extracts from turions of the monoecious biotype had major bands at 59 and 55 kDa after electrophoresis under denaturing conditions.

Antisera were raised against the proteins from the dioecious turion at Rf 0.45 after electrophoresis under non‐denaturing conditions. When blots of gels run under non‐denaturing conditions were probed with these antisera, a complex band was seen at Rf 0.45 for extracts of the dioecious biotype, while bands were observed at Rf 0.43 and 0.45 for the monoecious extracts. After electrophoresis under denaturing conditions, immunoreactive bands were noted at 58 and 57 kDa or 59 and 55 kDa in extracts of dioecious and monoecious turions, respectively.

Extracts of leaves and stems of H. verticillata had detectable amounts of immunoreactive proteins, regardless of photoperiod, hence turion production. Related plants with the aquatic habit had immunoreactive proteins in their leaves and organs of perennation [Elodea canadensis Michx., Elodea nuttallii (Planch.) St. John, and Egeria densa Planch., Potamogeton nodosus Poir. and P. pectinatus L.], but the presence of these proteins was not noted in other plants (Zea mays L., Allium cepa L., Spinacia oleracea L., Lemna gibba L., or Solanum tuberosum L.).
Effect of moderate salinity on patterns of potassium, sodium and chloride accumulation in cells near the root tip of barley: Role of differentiating metaxylem vessels
Authors: Huang Cheng X. , Van Steveninck Reinhard F. M.
Published: May 2006

X‐Ray microanalysis of fully hydrated, bulk‐frozen samples was used to measure concentrations of potassium, sodium and chloride in various cell types along seminal roots of barley (Hordeum vulgare L. cv. California Mariout) seedlings (1 to 150 mm from the tip). In the cytoplasm of all meristematic cells 1 mm from the root tip, the average concentrations of potassium and chloride were ca 200 and 15 mM, respectively. The potassium level was also high in the vacuoles of incipient xylem elements and did not drop to significantly lower values until 10 mm from the tip in protoxylem, 50 mm in early metaxylem and 150 mm in late metaxylem (LMX). Light microscopy observations (Nomarski optics) of hand‐cut sections showed the presence of cytoplasmic strands and also the presence of intact cross walls in LMX up to a distance of 100 mm. Both quantitative analysis of ion contents and structural observations suggested that LMX elements act as a large transitional sink of accumulated ions and therefore may not function as a main pathway of transport until perforation of the end wall takes place 100–150 mm from the root tip. Treatment with 50 mM NaCl resulted in higher concentrations of sodium and chloride in LMX elements than in the surrounding cells, suggesting that living xylem elements, which develop a large central vacuole at an early stage of root differentiation, may assist in alleviating salinity stress in the meristematic region of barley root tips. Further, it is proposed that reabsorption of sodium and chloride from the LMX, especially before the disappearance of the cross walls, may provide a means of salinity tolerance.
Excretion of ions (Cd2+, Li+, Na+ and Cl−) by Tamarix aphylla
Authors: Hagemeyer Jürgen , Waisel Yoav
Published: May 2006

Excretion of minerals by the NaCl‐resistant and comparatively cadmium‐resistant tree Tamarix aphylla (L.) Karst, was investigated. Cd2+ was excreted by plants exposed for 1–10 days to 9 or 45 μM Cd2+ solutions. Excretion of this toxic ion increased considerably with time but was less than 5% of the quantities that had been accumulated in the shoots. Excretion of Na+ and Cl− was positively correlated with NaCl concentration (1.5, 10, 50 mM) of the medium. The Na+/Cl− ratios of the excrete were positively correlated with the concentration of the treatment solution. Ca2+ excretion decreased with increasing NaCl concentrations of the solution. Excretion of K+ and Mg2+ was only little affected by NaCl. Excretion of Li+ occurred whenever this element was supplied in the uptake solution; daily excretion rates of Li+ increased with time. The ecological significance of excretion is discussed in relation to the low selectivity of the mechanism in T. aphylla.
The effect of an elevated atmospheric CO2 concentration on growth, photosynthesis and respiration of Plantago major
Authors: Poorter Hendrik , Pot Sander , Lambers Hans
Published: May 2006

The effect of an elevated atmospheric CO2 concentration on growth, photosynthesis and root respiration of Plantago major L. ssp. major L. was investigated. Plants were grown in a nutrient solution in growth chambers at 350 and 700 μl I−1 CO2 during 7 weeks. The total dry weight of the Co2‐enriched plants at the end of this period was 50% higher than that of control plants. However, the relative growth rate (RGR) was stimulated only during the first half of the growing period. The transient nature of the stimulation of the RGR was not likely to be due to end‐product inhibition of photosynthesis. It is suggested that in P. major, a rosette plant, self‐shading causes a decline in photosynthesis and results in an increase in the shoot: root ratio and a decrease in RGR. CO2‐enriched plants grow faster and cosequently suffer more from self‐shading. Corrected for this ontogenetic drift, high CO2 concentrations stimulated the RGR of P. major throughout the entire experiment.
Effect of paclobutrazol on membrane lipids in apple seedlings
Authors: Wang S. Y. , Sun T. , Whitaker B. D. , Faust M.
Published: May 2006

The effect of paclobutrazol [(2RS, 3RS)‐1‐(4‐chlorophenyl)‐4,4‐dimethyl‐2‐(1,2, 4‐triazol‐1‐yl) pentan‐3‐ol] on the fatty acid composition of polar lipids and on the sterol content in apple (Malus domestica Borkh. cv. York Imperial) seedlings was determined. Polar lipids isolated from leaves, stems and roots included mono‐ and digalactosyldiglycerides and the phospholipids phosphatidylinositol, phosphatidylcholine, phosphatidylglycerol and phosphatidylethanolamine. The predominant fatty acids in membrane polar lipids were palmitic (C16:0), linolnic (C18:2) and linolenic (C18:3). The predominant sterol, both free and esterified, was β‐sitosterol. There were no significant alterations in the fatty‐acid composition of glyco‐ and phospholipids from paclobutrazol‐treated apple seedlings. In contrast, a significant decrease in the content of β‐sitosterol and campesterol occurred in treated tissues. The decline in sterol content continued with increasing duration of paclobutrazol treatment, and was most pronounced in the root tissue.
In vitro regeneration and genetic manipulation of grasses
Authors: Ozias‐Akins Peggy , Vasil Indra K.
Published: May 2006

Regeneration of plants from cultured cells is an important and essential component of plant biotechnology. Advances in the recovery of plants from cultured cells and protoplasts of grasses, and in genetic transformation provide challenging opportunities for the genetic manipulation and improvement of this most important group of food plants.
Nutrition and growth of birch seedlings at varied relative phosphorus addition rates
Authors: Ericsson Tom , Ingestad Torsten
Published: May 2006

Birch (Betula pendula Roth.) 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−3 and was generally < 1 μmol dm−3 immediately 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 Rp applied 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 above optimum.
Inhibition of plasma membrane redox activities and elongation growth of soybean
Authors: Morré D. James , Crane Frederick L. , Barr Rita , Penel Claude , Wu Lian‐Ying
Published: May 2006

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 and p‐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 elongation growth in plants.
Monitoring chilling injury: A comparison of chlorophyll fluorescence measurements, post‐chilling growth and visible symptoms of injury in Zea mays
Authors: Hetherington Suzan E. , Öquist Gunnar
Published: May 2006

Changes in chlorophyll fluorescence emission from maize (Zea mays L. 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. FR decreased 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 FR in 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 FR during 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 chlorophyll fluorescence.
Micromorphological studies of adventitious bud formation on Picea abies embryos treated with cytokinin
Authors: von Arnold S. , Alsterborg E. , Walles B.
Published: May 2006

Embryos of Picea 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 bud primordium.
The control of protein breakdown and synthesis in the senescence of oat leaves
Authors: Veierskov Bjarke , Thimann Kenneth V.
Published: May 2006

During the senescence of detached first leaves of oat (Avena sativa L. 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 senescence.
Purification, characterization and storage of mitochondria from Jerusalem artichoke tubers
Authors: Lidén Annika C. , Møller Ian M.
Published: May 2006

Crude mitochondria isolated from Jerusalem artichoke (Helianthus tuberosus L.) 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.
Root development in winter wheat grown at different N/P supply: Root length patterns and N‐P interactions in phosphate uptake
Authors: Adalsteinsson Sveinn , Jensén Paul
Published: May 2006

Effects of different N/P ratios on several root parameters and on net P uptake were studied in winter wheat, Triticum aestivum cv. 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 stressed.
ATPase activity in plasmalemma‐rich vesicles isolated by aqueous two‐phase partitioning from Vicia faba mesophyll and epidermis: Characterization and influence of abscisic acid and fusicoccin
Authors: Blum Wilfried , Key Göran , Weiler Elmar W.
Published: May 2006

Plasmalemma‐rich microsomal vesicles were prepared from whole leaf and acid‐washed epidermal tissue of Vicia faba L. 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, Km for ATP 0.60 mM(whole leaf) and 0.67 mM (epidermis). Vmax ‐480 nmol (mg protein)1 min1 (whole leaf) and 510 nmol (mg protein)1 min1 (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 μM level 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 FC and ABA with the ATPase.
The marginal regions of thylakoid membranes: A partial characterization by polyoxyethylene sorbitan monolaurate (Tween 20) solubilization of spinach thylakoids
Authors: Webber Andrew N. , Platt‐Aloia Kathryn A. , Heath Robert L. , Thomson William W.
Published: May 2006

The detergent Tween‐20 solubilized preferentially portions of the marginal regions of Spinacea oleracea L. 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 discussed.
Effect of tentoxin on K+transport in winter wheat seedlings of different K+‐status
Authors: Klotz Martin G. , Erdei László
Published: May 2006

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 aestivum L. 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 pM tentoxin 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 mM K+, 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 rather than to a direct influence of tentoxin on H+‐ATPase.
Deposition of callose in relation to abscission of citrus leaves
Authors: Jaffe Morecai J. , Goren Raphael
Published: May 2006

When leaves of Citrus sinensis (L.) Osbeck cv. Shamouti senesce, they become more susceptible to abscission and the proximal 2 mm of their lamina‐petiole abscission zones exhibit callose deposition. The degree of senescence, assayed with the DAR‐WIN image processor (Telewski et al. 1983), was positively correlated in a linear fashion with callose deposition. Explant of non‐senescing leaves were observed. Excision of the leaf at the stem‐petiole junction induced callose deposition throughout the petiole, but not in the lamina. Callose deposition began immediately upon excision and reached a maximum at 3 h. It then decreased slightly and remained at the same level for up to 5 days. Exogenous compounds that decrease callose deposition, e.g. laminarase and 2‐deoxy‐D‐glucose, inhibited the rate of abscission of explants. Compounds that promote callose deposition, e.g. uridine diphosphoglucose and mannose, increased the rate of abscission of explants. Exogenous callose, e.g. laminarin, increased the rate of abscission. It is not known how callose might be causally involved in promoting abscission.
Effects of applied NaCl on Opuntia humifusa
Authors: Silverman F. Paul , Young Donald R. , Nobel Park S.
Published: May 2006

Plant morphology in the field in Virginia, USA, and growth responses to applied NaCl in a glasshouse were determined for two populations of Opuntia humifusa (Rafinesque) Rafinesque, one from an inland site and the other from the marine strand, which differed in potential exposure to salinity. Cladode dimensions, plant height and rooting depth varied significantly between the populations. Application of NaCl in 50 mM increments up to 400 mM every 3 days for 6 weeks caused the cladodes to decrease up to 30% in thickness, the decrease being about 20% more at 50 to 150 mM NaCl for plants from the inland site than from the marine strand. Inhibition by 150 mM NaCl of the maximum rate of net CO2 uptake and of the total CO2 uptake over a 24‐h period was greater for the inland population. Growth, especially of roots, was inhibited by applied NaCl, with a decrease in biomass above 200 mM NaCl for plants from the inland site and not until 400 mM for those from the marine strand. Although the root Na+ level was the same for plants from the two populations, reaching a maximum of about 8 mg (g dry weight)−1 at 200 mM NaCl, the cladode Na+ level was two‐fold higher for plants from the marine strand than from the inland site. Thus, exclusion of Na+ from the cladodes is not the reason for the greater NaCl tolerance of O. humifusa from the marine strand, which is a habitat that can experience periodic episodes of high salinity.
Host range differentiation of spore‐positive and spore‐negative strain types of Frankia in stands of Alnus glutinosa and Alnus incana in Finland
Authors: van Dijk Cornells , Simmer Aria , Weber Assi
Published: May 2006

Host compatibility of different spore‐positive (Sp+)and spore‐negative (Sp−) strain types of Frankia from alder stands in Finland was studied in Modulation tests with hydrocultures of Alnus glutinosa (L.) Gaertner, A. incana (L.) Moench and A. nitida Endl. Root nodules and soil samples from stands of A. incana (Lammi forest and Hämeenlinna forest) were dominated by Sp + types of Frankia (coded AiSp+ and AiSp+ H. respectively), which caused effective root nodules in test plants of A. incana, but failed to induce nodules in A. nitida. In A. glutinosa Frankia strain types AiSp + and AiSp + H caused small, ineffective root nodules with sporangia (coded Ineff −), which were recognized by the absence or near absence of vesicles in the nodule tissue. Ineffective nodules without sporangia (coded Ineff −) were induced on A. glutinosa with soil samples collected at Lammi swamp. The spore‐negative strain type of Frankia was common in root nodules of A. glutinosa in Finland (Lammi swamp) and caused effective Sp− type root nodules (coded AgSp −) in hydrocultures of A. incana, A. glutinosa and A. nitida. A different Sp + strain type of Frankia. coded AgSp+ Finland, was occasionally found in stands of A. glutinosa. It was clearly distinguished from strain type AiSp + by the ability to produce effective nodules on both A. glutinosa and A. incana. The nodulation capacities of soil and nodule samples were calculated from the nodulation response in hydrocutlure and served as a measure for the population density of infective Frankia particles. Sp + nodules from both strain types had equal and high nodulation capacities with compatible host species. The nodulation capacities of Sp type root nodules from A. glutinosa were consistently low. High frequencies of Frankia AiSp+ and AiSp+ H were found in the soil environment of dominant AiSp + nodule populations on A. incana. The numbers of infective particles of this strain type were insignificant in the soil environment of nearby Sp − nodule populations on A. glutinosa and in the former field at Hämeen‐linna near the Sp+ nodule area in Hämeenlinna forest. Strain type AgSp− had low undulation capacity in the soil environment of both A. incana and A. glutinosa stands, Explanations for the strong associations between Frankia strain types AiSp+ and AiSp − H and A. incana and between strain type AgSp− and A. glutinosa are discussed in the light of host specificity and of some characteristics of population dynamics of both strain types. The possible need to adapt the concept of Frankia strain types Sp + and Sp − to strains with some variation in spore development was stressed by the low potentials of strain type AiSp + H to develop spores in symbioses with hydrocultures of A. incnna.
Endogenous elemental sulfur (S°) in dormant and aging α‐spores of Phomopsis viticola
Authors: Beffa Trello , Pezet Roger , Turian Gilbert
Published: May 2006

Endogenous elemental sulfur (S°) was measured in dormant α‐spores of Phomopsis viticola Sacc. (ATCC 44940) from young (25‐day‐old) and aging (105‐day‐old) cultures grown on malt extract agar medium enriched with [35S]‐MgSO4. Endogenous S° from the mitochondrial fraction, and the lipid and aqueous cytoplasmic fractions of young and aging α‐spores were purified by column chromatography followed by thin‐layer chromatography. The purity of mitochondrial pellets were checked by the catalase (EC 1.11.1.6) and acid phosphatase (EC 3.1.3.1) activities. Activities of the mitochondrial enzymes NAD+‐isocitrate dehydrogenase (EC 1.1.1.41) and cytochrome c oxidase (EC 1.9.3.1) were also measured to determine the distribution of the endogenous S° between mitochondria and cytoplasm.

In young dormant α‐spores, endogenous S° was mostly found in the cytoplasmic lipid reserves, which were mainly phospholipids. The mitochondrial fraction of these young α‐spores contained ca 10% of the total endogenous S°, whereas in aging α‐spores stored for 105 days the endogenous S° was mainly (ca 90%) localized in the mitochondrial fraction. This accumulation of S° in mitochondria of aging α‐spores was correlated with a sharp decrease in phospholipid reserves, endogenous and exogenous respiratory activities, ATP concentration, uptake of sulfate, and NAD+‐isocitrate dehydrogenase and cytochrome c oxidase activities. These metabolic changes were correlated with an irreversible loss of germination capacity which leads to the natural death of P. viticolaα‐spores.

During the first min of the breaking of dormancy, the young α‐spores possess a 7.3‐fold capacity to reduce exogenous S° with production of hydrogen sulfide, as compared to the aging α‐spores. In young α‐spores the production of hydrogen sulfide was almost totally inhibited by 40 μM antimycin A (92%), and strongly inhibited by 2mM azide (75%) and by 15 μM 2,4‐dinitrophenol (63%).

Our work suggests that endogenous S° plays a key role in the regulation of the dormancy and aging processes of α‐spores of P. viticola.
Callus formation from cotyledon protoplasts of Pinus oocarpa and Pinus patula
Authors: Lainé E. , David H. , David A.
Published: May 2006

Protoplasts were isolated from cotyledons of 11‐day‐old seedlings of Pinus oocarpa and P. patula ssp. tecunumanii. The best enzyme combination was Cellulase R10 + Pectolyase Y‐23, associated with bovine serum albumin. When cultured at a low density [1.25 × 103 to 5 × 103 protoplast (ml)−1] in a liquid medium, the cells divided. The medium contained glutamine and casein hydrolysate as nitrogen sources, and glucose as osmoticum. Rate of division was increased by supplementing the medium with l‐ornithine, putrescine and spermidine. However, the rate remained low, with an absolute division frequency of ca 1%. Dilution allowed colony proliferation and fragmentation, leading to the formation of numerous microcalli that could be transferred to various solid media for further growth.
Phosphate transport in potato cuttings: Effect of gibberellic acid and abscisic acid
Authors: Poder Danielle , Suleiman Sausan , Penot Michel
Published: May 2006

Apical cuttings of Solanum tuberosum L. cv. Sirtema were used al different stages of development to study long‐distance transport of phosphate. The effects of two hormones, gibberellic acid (GA3) and abscisic acid (ABA), on this process were also investigated. Before tuberization, phosphate (32P) supplied to a single leaf was transported preferentially in the young and growing parts of the plant: apical bud, young leaves and roots. After tuberization, the tuber became the principal site of phosphate accumulation. GA3 treatment (10−4 M) of the tuber as well as of the leaves led to reduced transport of 32P into the tuber. By contrast, treatment of the tuber with ABA (10−4M) did not change the 32P distribution within the plant, while foliar spray with ABA greatly increased the transport into the tuber. The opposite effects of the two hormones on phosphate accumulation by tubers are discussed with regard to their opposite effects on the tuberization process.
Free and conjugated desmethylsterol composition of Zea mays hybrids exposed to mild osmotic stress
Authors: Simonds Jean M. , Orcutt David M.
Published: May 2006

Five hybrids of Zea mays (A619 × H60, B73 × MO17, B73 × PA91, B73 × VA17. A632 × H96) were grown hydroponically at osmotic potentials of ‐0.1 (control), ‐0.4 and ‐0.6 MPa. Dry weights of hybrids B73 × VA17 and A632 × H96 decreased significantly at ‐0.4 and ‐0.6 MPa. Few changes were observed in the free sterol, steryl glycoside and steryl ester fractions. However, steryl esters of the roots and stems of osmotically treated plants declined in most of the hybrids. The stigmasterol to sitosterol ratio increased in all three steryl fractions in the roots of B73×VA17 and A632×H96 as a result of the osmotic treatments. B73×VA17 and A632×H96 also exhibited the greatest initial electrolyte leakage when leaf dises were subjected to osmotic stress. A632×H96 and possibly B73×VA17 were less tolerant to osmotic treatments than the other hybrids. Modification of sterols may reflect initial events that lead to the stabilization or destabilization of cellular membrances which in turn may affect the tolerance of plants to stressful environments.
Identification of tryptophan in leachate of oat hulls (Avena sativa) as a mediator of root growth regulation
Authors: Häggquist M.‐L. , Strid L. , Widell K.‐O. , Liljenberg C.
Published: May 2006

Leachate of oat hulls (Avena sativa L. cv. Sang) inhibits root elongation and causes swollen roots and abundant root hair formation. The active substance was isolated by column chromatography and thin layer chromatography (TLC) systems. High performance liquid chromatography (HPLC) revealed 3 peaks, one of which corresponded to the substance responsible. The latter was identified as tryptophan by means of its UV spectrum, amino acid analysis, nuclear magnetic resonance spectrometry (NMR) and mass spectrometry (MS).
Photomodulation of mesocotyl elongation in maize seedlings: Is there a correlative relationship between phytochrome, auxin and cell wall extensibility?
Authors: Yahalom A. , Epel B. L. , Glinka Z.
Published: May 2006

Three h white light irradiation of etiolated maize seedlings (Zea mays L. cv. Jubilee) inhibited mesocotyl elongation and caused a sharp decrease in cell wall plastic extensibility as measured by the Instron technique. The plastic extensibility following white light irradiation (3 h) was photomodulated by phytochrome. Although the photomodulation of the plastic extensibility was correlated with growth during 20 h, no such correlation was observed at shorter times. The addition of indole‐3‐acetic acid to light‐inhibited intact seedlings, or seedlings from which the coleoptile and inner leaves were excised, resulted in a stimulation of growth. However, none of the IAA concentrations could reverse light inhibition. The possibility of a correlative relationship between phytochrome, auxin and cell wall extensibility is discussed.
Regulation of enzyme activity in plants by reversible phosphorylation
Authors: Budde Raymond J. A. , Chollet Raymond
Published: May 2006

This paper reviews the seven specific plant enzymes which have been shown or suggested, to date, to undergo reversible covalent modification by regulatory phosphorylation, including mitochondrial pyruvate dehydrogenase (EC 1.2.4.1), chloroplastic pyruvate, orthophosphate dikinase (EC 2.7.9.1) and ribulose bisphosphate carboxylase/oxygenase (EC 4.1.1.39), cytoplasmic phosphoenolpyruvate carboxylase (EC 4.1.1.31) and 6‐phosphofructo‐2‐kinase (EC 2.7.1.105), microsomal hydroxymethylglutaryl ‐ CoA reductase (EC 1.1.1.34), and quinate: NAD+ oxidoreductase (EC 1.1.1.24).
Penetration of blue nad UV radiation measured by fiber optics in spruce and fir needles
Authors: Bornman Janet F. , Vogelmann Thomas C.
Published: May 2006

The penetration of blue light (460 nm) and UV‐A (360 nm) radiation into needles of spruce (Picea engelmannii Parry ex. Engelm.) and fir [Abies lasiocarpa (Hook.) Nutt. var. Iasiocrpa] was examined. The distribution of collimated and scattered light in intact needles was measured by quartz fiber optic microprobes. Both blue light and UV‐A were attenuated more rapidly with depth in fir than in spruce, although the light profiles for the two light regimes were different; blue light penetrated to a greater depth than UV‐A, Removal of the epicuticular wax from the needle surface increased the amount of internal blue light slightly, but had little effect on the amount of UV‐A. The differences in light penetration in light penetration in spruce and fir may be caused bhy different pigmentation and leaf anatomy.
Fiber optic studies of light gradients and spectral regime within Lactuca sativa achenes
Authors: Widell Karl Olof , Vogelmann Thomas C.
Published: May 2006

Light gradients and spectral regime were measured in Lactuca sativa L. cv. Grand Rapids achenes using fiber optic microsensors. The distribution of scattered light across lettuce achenes was linear for 660 and 730 nm and non‐linear for 450 nm light. Spectra for scattered light within intact achenes also showed a non‐linear increase with wavelength. The preferential attenuation of blue light by the pericarp and seed explains in part the relative ineffectiveness of blue light with respect to red in triggering germination of lettuce. Calculated action spectra for phytochrome‐stimulated germination agree closely in the red with experimentally derived action spectra; however, there is little agreement within the blue.
The existence of ornithine decarboxylase‐antizyme complex in germinated barley seeds
Authors: Koromilas Antonis E. , Kyriakidis Dimitrios A.
Published: May 2006

Ornithine decarboxylase (ODC; EC 4.1.1.17) and its antizyme (Az), a protein non‐competitive inhibitor of ODC, form a complex in germinated barley (Hordeum vulgare L. cv. Georgia) seeds. The ODC‐Az complex is very stable, but dissociates by treatment with 10% ammonium sulfate. ODC‐Az complex is present in the cytosol, and it can also be extracted from germinated barley seed chromatin with 2 M NaCl.
Properties of reformed prolamellar bodies from illuminated and redarkened etiolated wheat plants
Authors: Minkov Ivan N. , Ryberg Margareta , Sundqvist Christer
Published: May 2006

Prolamellar bodies were isolated from etiolated leaves of wheat (Triticum aestivum L. cv. Walde, Weibull), which were illuminated for 4 h and then grown in darkness for 16 h. The inner etiochloroplast membranes were isolated by differential centrifugation, and prolamellar bodies and thylakoids were separated on a 10–50% continuous sucrose density gradient. The reformed prolamellar bodies contained phototransformable protochlorophyllide as the main pigment as shown by low temperature fluorescence spectra and high performance liquid chromatography. After illumination with 3 flashes of white light almost all of the protochlorophyllide was transformed to chlorophyllide. In the thylakoids, however, most of the protochlorophyllide was not phototransformed. The reformed prolamellar bodies and the thylakoids showed a fluorescence emission ratio 657/633 nm of 5.6 and 0.5, respectively. Both membrane systems contained also chlorophyllide and chlorophyll synthesized during the illumination. Polyacrylamide gel electrophoresis showed the main chlorophyllide oxidoreductasse.

Teransmission and scanning electron micrographs indicated that the reformed prolamellar bodies are mainly of the “narrow” type and that the prolamellar body fraction had only a minor contamination with thylakoid membranes.

The results obtained showed that reformed prolamellar bodies isolated from illuminated redarkened etiolated wheat leaves had features very similar to the prolamellar bodies isolated from etiolated leaves. This provides support for the idea that prolamellar bodies are an important natural membrane system which plays a dynamic role in the development of the etio‐chloroplasts in light.
Mineral and lipid composition of Glycine ‐ Glomus ‐ Bradyrhizobium symbioses
Authors: Pacoysky Raymond S. , Fuller Glenn
Published: May 2006

Soybean [Glyeine max (L.) Merr. cv. Amsoy 71] plants were inoculated with either the vesicular‐arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum. with a strain of Bradyrizobobium Japonicum. or with both endophytes in combintion. Noninoculated controlplantes were fertilized with levels of N and P previously found to compensate for nutrient input following infection by Bradyhizobium or Glomus Temporal differences in N and P assimilation in nodulated or mycorrhizal plants indicated that Glomus was most effective during early vegetative growth and Bradyrhizobion was active until the mid‐pod‐fill stage in soybean. In general. soybeans colonized by Glomus contained more Cu but less Mn and P than corresponding P‐fertilized plants. Soyubean roots infected with G. fasciculaum contained five unusual fatty acids: [16: 1 (11c): 8:3 (6c, 9c, 12c): 20:3 (8c, 11c, 14c): 20:4 (5c, 8c, 11c, 14c): 20:5 (5c, 8c, 11c, 14c, 17c)] that were absent in non‐infected roots. Fatty acid 16:1 (11c) comprised 43% of total fatty acids in Glomus‐infected roots at week 9 and 29% of total root fatty acids at week 15. This isomer of hexadecenoic acid was positively correlated with vesicle number (r = 0.92**). and 16:1 (11c) was probably the principalstorage fatty acid in fungal vesicles. These five unusual fatty acids were not found in the leaves. pods or seeds of either VAM or non‐VAM plants. Specific leaf area increased with time in nodulated soybeans. but these plants contained lessCu than corresponding N‐fertilized plants. Soybeans nodulated with Bradyrthizobium contained more total lipid and proportionately more fatty acid 16:0 than N‐fertilized plants. Infection by Glomus or Bradyrhizobium also altered the fatty acid composition of above‐ground plant parts, although these changes were subtle compared to the markedly different fatty acid found in Glomus‐infected roots. These findings suggest that seed quality may be altered due to the physiological changes resulting from infection by N2‐fixing bacteria and/or endomycorrhizal fungi. Observed differences in the plant nutrition of inoculated soybeans could not be replicated by fertilizer addition alone.
Ca2+‐dependent in vitro phosphorylation of soluble proteins from germinating wheat (Triticum turgidum) endosperm
Authors: Krishnan Hari B. , Pueppke Steven G.
Published: May 2006

A 40000 g supernatant fraction from extracts of germinating wheat (Triticum turgidum Desf. cv. Edmore) endosperm contains protein kinase activity that phosphorylates several endogenous proteins. In vitro incorporation of radiolabel from [32P]‐ATP into phosphoproteins was maximal in the presence of 1 mM CaCl2 and 5 mM MgCl2Ca2+ at micromolar concentrations greatly stimulated the phosphorylation of 49 and 47 kDa polypeptides and also inhibited the phosphorylation of a few specific polypeptides. The phosphorylation of the 49 and 47 kDa polypeptides was present at 2 days after seed germination and was maximal at 8 days. Quantitative protein changes were also detected during the seed germination, but differences could not be correlated with changes in protein phosphorylation. Phosphoamino acid analysis by two dimensional thin‐layer electrophoresis showed that the Ca2+‐dependent protein kinase phosphorylates a serine residue of the 47 kDa polypeptide. Ca2+‐dependent protein kinase phosphorylates a serine residue of the 47 KDa polypeptide. Ca2+ dependent protein phosphorylktion was inhibited by phenothiazine‐derived drugs. Addition of S‐adenosylmethionine to the in vitro phosphorylation reaction specifically inhibited the Ca2+‐dependent protein phosphorylation.
Nitrate and hydrogen peroxide metabolism in Medicago sativa nodules and possible effect on leghaemoglobin function
Authors: Becana M. , Aparicio‐Tejo P. , Sánchez‐Diaz M.
Published: May 2006

The effect of NO3 (0–20 mM for 7 days) upon NO3 and H2O2 metabolism in lucerne (medicago sativa L. ev. Aragón) nodules initiated by Rhizobium meliloti strain 102F51 has been examines. Ty;pical nitrate reductase, (NR) activities of bacteroids (EC 1.7.99.4) and cytosol (EC 1.6.6.1) of nodules not treated with NO3 were 60 and 45 nmol NO2 formed (mg protein)1h−1 respectively, Inductin of bacteroid NR took place in nodules exposed ot concentrations above 5 mM No3 whereas cytosol NR was induced at 5 mM No3 decreasint at greater NO3 concentrations. In resonse to NO3 additin, NO2 increasingly accumulated in the nodule cytosol at quantities commensurate with those needed to oxidise leghaemoglobin (Lb) in vitro. A comparison of patterns of NO2 accumulation and activities of NRs expressed on a nodule weight basis indicates that plant NR contributes decisively to NO2 production at the earlier phass of nodule senescence (5–10mM No3 while bacteroid NR becomes increasingly important in generating NO2 at nore advanced stages (10–20mM NO3). Specific superoxide dismutase (SOD; EC 1.15.1.1) and catalase (EC 1.11.1.6) activities of bacteroids remained constant during the NO3 induced senescence of nodules whereas SOD activity of cytosol increased 1.5‐fold and catalase activity ws inhibited by 20% at 20 mM NO3 substantial peroxidase (EC 1.11.1.7) activity was found in the plant but none in the bacteroid fraction of nodules. Peroxidase activity increased significantly only at 20 mM NO3 concomitantly with malondialdephyde content. concentrations. Free H2O2 interferes wihjt Lb function in vivo is suggested.
Autolysis of the cell wall. Its possible role in endogenous and IAA‐induced growth in epicotyls of Cicer arietinum
Authors: Seara Javier , Nicolás Gregorio , Labrador Emilio
Published: May 2006

Indoleacetic acid (IAA), a factor that induces growth in epicotyls of cicer arietinum L. cv. Castellana, increases the autolytic capacity of the cell walls by 50%, suggesting that autolysis is related to the processes of cell wall loosening that accompany growth. IAA promotes an increase in the specific activities of the enzymes involved in autolysis, mainly α‐galactosidase (EC 3.2.1.22). This relationship autolysis‐growth. was also observed in a study of the autolytic capacity of cell walls from regions of the epicotyl with different growth capacity. The sugars released and the level of enzymatic protein were higher in the subapical region that towards the base.
The effect of butyrate on cell cycle progression in Allium cepa root meristems
Authors: Lanzagorta J. M. Alicia , de la Torre Consuelo , Aller Patricio
Published: May 2006

Sodium butyrate at 4 mM and above blocked cell proliferation in root meristems of Allium cepa L. bulbs. Cytophotometric determinations in asynchronously growing cells, as well as cycle kinetics in synchronous binucleate cells. indicated that blocking took place at mid‐G1 and at, or close to, the S/G2 border. Cell progression through S phase and mitosis was little affected. The cell cycle blockage induced by 6 mM butyrate was reversible when the drug was applied for periods of time not exceeding 12 h. Butyrate did not affect nucleic acid and protein synthesis activities, though its action on the cell cycle ressembled that produced by translation inhibitors.