摘要:

The kinetics of root gravicurvature of intact maize (Zea maysL., cv. LG 11) seedlings can be separated into two steps. From 0 to 2 h, a rapid downward bending, enhanced by light, occurred. During the next 4 h (2 to 6 h) no further curvature appeared in the dark, whereas it continued in light. The final root gravicurvature was greater for light‐than dark‐treated seedlings. Growth was particulary inhibited during the first 2 h.When intact seedlings were placed horizontally and returned to the dark after a 4 h light pretreatment in a vertical position, only the second step (2 to 6 h) was changed. A negative gravitropism, associated with a stimulation of growth, appeared. Thus, when gravireaction took place in darkness, the final root gravicurvature was similar for the light‐pretreated intact seedlings and the dark control. Using apical root segments, this phase of negative gravicurvature was not observed although the stimulation of gravicurvature of light‐pretreated roots remained. Similar experiments were performed with seedlings having coleoptile or endosperm removed, after intact seedlings had been exposed to a light pretreatment, and gravireaction took place in the dark. Results indicated that these two organs could play an essential role in the development of gravicurvature and in the regulation of the light effects, respe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04133.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Purified plasma membranes were prepared from needles of Scots pine (Pinus sylvestris L., Provenance Sodra Ydre), and the behavior of a K+ stimulated Mg2+‐dependent ATPase was studied. The microsomal fraction (1000‐30 000 g) was used for partition in a dextranpolyethylene glycol two‐phase system. Both upper and lower phases were washed twice with new upper and lower phase, respectively, yielding the fractions U3 and L3. After staining with STA (silicotungstic acid) and examining with an electron microscope, an enrichment of the plasma membranes in the U, phase was seen. This fraction was also enriched in K+ stimulated Mg2+‐dependent ATPase. The ATPase was rather specific towards ATP compared to other nucleosides, and had a pH optimum between 6 and 7. The activity of this ATPase was followed during a frost hardening‐dehardening cycle and showed an increased activity towards the end of the hardening period, whereas the activity decreased to normal during the dehardeni

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04134.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Macromolecular synthesis of asexual spores of Aphanomyces astaci Schikora, strain is, was studied during the germination phase. Germination of the spores was completely inhibited by aclinomycin D (20 ug/ml) or cycloheximide (100 ug/ml) as was incorporation of labeled uridine and leucine, respectively. During spore germination protein synthesis was almost linear, whereas incorporation of [3Hl‐uridine and [3H1‐thymidine showed lag phases. Initial protein synthesis is therefore suggested to take place without concomitant RNA‐synthesis in this species. Germlings were not developmentally competent to sporulate before 8 h of germin

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04135.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The seeds (achenes) of Laportea bulbifera require a chilling to break their dormancy and are negatively photoblastic. Their germination is inhibited by both continuous blue light and continuous or prolonged far‐red radiation. The germination of de‐coated seeds, prepared by removing the fruit coats, however, was strongly inhibited by continuous far‐red, but not by continuous blue light. Photoreversible germination by a brief irradiation with red light occurred when the chilled seeds were exposed to prolonged far‐red light. These results suggest that far‐red light may regulate the germination of L. bulbifera seeds through the phytochrome system which exists in the regions other than fruit coats and that the blue light reaction may be governed by other photoreceptor

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04136.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Exudation of cations and of amino acids from detached oat seedling leaves (Avena sativaL. cv. Victory) floated on water or solutions was measured under varied conditions. A small amount of exudation in the first 4 h, greater in the dark than in white light, is followed, one to 8 days later, by a relatively great increase which approximately accompanies senescence. This second increase is delayed by kinetin and is accelerated by abscisic acid or methyl jasmonate. both of which accelerate senescence. A nitrogen atmosphere (in darkness) causes immediate large exudation, mainly of potassium ions, and this is effectively delayed by light. There are two exceptions to the parallel between exudation and senescence; n‐pentanol, which strongly delays senescence in darkness, nevertheless increases exudation both of potassium and of amino acids, probably due to a direct effect on the plasmalemma. Cycloheximide, which also delays senescence, increases the exudation somewhat. Kinetin prevents or delays exudation under all conditions. Thus, the permeability of the plasmalemma increases greatly along with other criteria of senescence, but this change is probably not the principal cause of the senescence syndrome. Some of the effects are considered to result from reduction in available energy and others from a direct influence on plasmalemma permeabilit

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04137.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The distribution of lectin in various tissues ofPhaseolus vulgarisL. (var. red) has been investigated with the use of a sensitive solid phase enzyme immunoassay. Plants were divided into roots, stems and leaves with a further dissection of the stem into internodes. Isolated tissues, from plants 3‐10 weeks old, were screened for their lectin content, and the development of the lectin over this period determined. Stems and roots contained significant amounts of lectin, whereas the leaves only exhibited very low levels. Furthermore, a pronounced and differential increase in the biosynthesis of the lectin was observed in stem sections between 6 and 10 weeks, where the third internode displayed the highest lectin leve

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04138.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The correlation between hypocotyl elongation, cell wall loosening and changes in cell wall polysaccharides was studied using intact lettuce seedlings grown in the dark or in light together with gibberellic acid (GA) and/or 5‐fluorodeoxyuridine (FUDR). The following results were obtained:1) The production of pectic, hemicellulosic and cellulosic polysaccharides look place in parallel with hypocotyl elongation, which was substantially affected by different growth conditions.2) The mole percentage sugar composition of pectic and hemicellulosic polysaccharides changed in response to dark, light, GA, or FUDR treatments.3) The amounts of xylose and glucose in hemicellulosic polysaccharides and those of galactosc, rhumnose and uronic acid in pectic polysaccharides increased in parallel with hypocotyl elongation.4) Statistical analysis of the quantitative relationship between sugars composing polysaccharides revealed that the uronic acid content changed in parallel with those of rhamnose and galactose in pectic polysaccharides, and the content of xylose varied in parallel with those of fucose and glucose.5) The content of hemicellulosic polysaccharides was correlated with cell wall loosening represented by a decrease in the minimum stress‐relaxation time. Changes in the stress‐relaxation time value were correlated with those in the content of araltinose and galactose in hemicellulosic polysaccharides.Based on these results, the relationship between hypocotyl elongation, changes in cell wall polysaccharides, and cell wall loosening is discussed with respect to the effect of GA and FUDR on hypocotyl elong

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04139.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Dark‐grown non‐dividing cells of Euglena gracilis Klebs var. bacillaris Cori were exposed to light for up to 72 h and thylakoid membrane fractions were isolated by sedimentation in sucrose step gradients at various stages of development. The membrane‐bound coupling factor (CF1)‐ATPase activity of these prothylakoids (0 h of light) and developing thylakoid membranes (12 to 72 h of light) was characterized by its cation specificity and sensitivity to inhibitors. The enzyme at all stages of development was activated by Mg2+ and to a lesser extent by Ca2+; Mn2+ was found to activate, as well as or better than Mg2 + at comparable concentrations. The activity of the enzyme was almost completely inhibited by dicyclohexylcarbodiimide (DCCD; 0.3 mM), but was insensitive to oligomycin, valinomycin and carbonyl cyanide P‐trifluoromethoxyphenylhydrazone (FCCP). Low concentrations of NH4CI gave a slight stimulation of enzyme activity, whereas high concentrations of the uncoupler were inhibitory. The specific activity of the membrane‐bound CF,‐ATPase was highest in prothylakoid membranes. Specific activity decreased on a thylakoid protein or chlorophyll basis during the first 12 h of development, and achieved a steady state level by 48 h following light induction. Estimates of total CF1‐ATPase activity per cell indicate that the time for major synthesis of the enzyme is between 12 and 3d h ol development. These results suggest that following an initial lag period in membrane development lasting about 12 h, there is a formation of CF1‐ATPase that accompanies further thylakoid mem

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04140.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In frost‐hardened spinach leaves (Spinucea oleracea L. ev. Vroeg Reuzenblad) an enhanced content of water‐soluble non‐protein sulfhydryl compounds was observed. The enhancement was due to higher levels of glutathione as well as to other non‐protein‐bound sulfhydryl compounds. In addition glutathione reductase activity was increased upon hardening. The affinity of the enzyme for oxidized glutathione was slightly lowered during hardening. The significance of glutathione accumulation during frost‐hardening is discussed. Exposure of spinach to NaCl‐stress did not affect the levels of glutathione and glutathione reductase of the leaves. In addition the kinetic properties of the enzyme remained unaltered by salinity. It is suggested that glutathione and glutathione reductase activity are not involved in adaptation of spinach to sali

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04141.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Protonemata of the mossFunaria hygrometricaSibth. (L.) show a strong pH dependence for auxin accumulation. IAA uptake is enhanced when the pH of the incubation medium is lowered from 7.6 to 4. In low light intensity grown protonemata (0.56 W m−2) a component of IAA uptake could be saturated by IAA; efflux of IAA could be inhibited by 2,3,5‐triiodobenzoic acid. This is explained by the presence of influx and efflux carriers for IAA. In protonemata grown at high light intensity (2.00‐2.30 W m−2) these carriers could not be shown to be present. These results are discussed with regard to the different physiological behavior of moss protonemata grown under different light con

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04142.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY