摘要:

Complete elimination of polyphenol oxidase activity in hypocotyls and leaves of developing mung bean (Vigna radiataL. Wilczek cv. Berkin) seedlings by tentoxin had no effect on the content of the ortho‐hydroxylated flavonoids delphinidin and rutin. Tentoxin completely eliminated polyphenol oxidase‐mediated ortho‐hydroxylation ofp‐coumaric acid to caffeic acid. Despite this, tentoxin had no effect on caffeic acid derivative contents in the seedlings. High performance liquid chromatography profiles indicated that elimination of polyphenol oxidase had no effect on either the quality or the quantity of soluble phenolic compounds, These data strongly indicate that polyphenol oxidase is not involved in metabolism of phenolic compounds in developing plant

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00696.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Controlled freezing methods adopted for Thermal Analysis (TA) and Differential Thermal Analysis (DTA), were used to investigate the capacity for subcooling short shoots ofPinus silvestrisL. of various ages. Both methods showed that there were no differences in subcooling temperature along the length of the short shoots. Differences in age and water content have a significant effect on the freezing profiles. Short shoots of the current years growth were able to subcool to about −13°C. One‐year‐old short shoots subcooled to about −9°C. There were no apparent variations in subcooling temperatures from June to September. Rainfall or dry periods had no effect on subcooling temperatures. The freezing profiles of living material was characteristic and was not repeated during subsequent freezing cycles. Detection of ice crystal formation during refreezing experiments indicated whether short shoots were aliv

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00697.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Photosynthetically fixed14C was analyzed in various chemical fractions from leaves and stems of cottonwood (Populus deltoidesBartr. ex. Marsh.) during dormancy induction. Dormancy was induced by 8‐h photoperiods and 20/14°C temperature regimes. Within 4 weeks under short days, terminal buds were set and leaf expansion and stem elongation had stopped.14C2was fed to a leaf at Leaf Plastochron Index 7 for 30 min. Either after this 30 min feeding period or after a 48‐h translocation period the plants were sampled, freeze‐dried, extracted and analyzed for14C.14C‐fixation decreased during dormancy induction from 60% to 17% of the 3.7 MBq14C applied at 0 week and 8 weeks, respectively. Percentage distribution of14C in chemical fractions of source leaves reflected leaf age and translocation inhibition. In rapidly growing plants, considerable14C was incorporated into leaf protein while most of the soluble14C‐sugars were either metabolized or translocated out of the leaf. After terminal bud set, the percentage of14C in the protein and residue fractions decreased rapidly and that in the sugar fraction increased. Percent distribution in stems closely reflected changing metabolic pathways of carbon flow as influenced by dormancy induction. For example, the14C in structural carbohydrates decreased in 5 weeks under short days from 65 to less than 10% of the14C recovered in the chemical fractions, thus indicating cambium inhibition. At the same time the percentage of14C in starch and sugar increased indicating storage. Short term (after 30 min) incorporation of14C into the protein and starch fractions of leaves changed relatively little throughout the 8‐week induction period. In contrast the turnover rates of these fractions (14C present after 48 h) increased considerably after active growth of the whole p

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00698.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The effect of potassium on the water potential, the osmotic potential and the pressure potential in younger and older leaves ofPhaseolus vulgarisgrown in hydroponic culture was studied. Inadequate potassium supply resulted in an increase of the osmotic potential. In the older leaves the water potential was raised, in the younger leaves the pressure potential was depressed in the treatment insufficiently supplied with potassium as compared with leaves with an adequate potassium supply. Cell size of the younger leaves was smaller in the treatment with the low K+supply in comparison with the leaves well supplied with K+. Potassium had a beneficial effect on plant growth, especially on fresh matter production. The water status of leaves (water content, pressure potential, osmotic potential) responded more sensitively to potassium supply than dry matter production. Besides organic N and organic anions, K+was the most abundant solute found in the press sap of the leaves. From the results it is concluded that K+is indispensible for attaining an optimum potential (turgor) in young leaves which in turn has an impact on plant growth.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00699.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

A comparison is made between pigment accumulation in pigment‐deficient genotypes of soybean (Glycine max) at any one sampling time (genotype control) and pigment accumulation for any one genotype as a function of development (development control). Plots of accessory chloroplast pigments against chlorophylashow various linear and non‐linear relationships that are similar whether generated by genetic differences or by the development process. These relationships are related to the formation and development of pigment‐protein complexes especially the relationship of carotenoids to these comp

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00700.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The effect of a temperature close to the freezing point (chilling) on the nitrate reductase system of leaf discs ofCucumis sativusL. cv. Kleine Groene Scherpe was determined in the absence and presence of light. The capacity of leaf discs in the light (250 μE m−2s−1) at 20°C to increase in vivo and in vitro nitrate reductase activity, was unaffected by chilling pretreatment in the dark, but 4 h of chilling pretreatment in the light (250 μE m−2s−1) decreased the capacity to less than 50% of the unchilled control. The chilling inhibition of the capacity to increase nitrate reductase activity was of a photooxidative nature since it only occurred in the presence of light and oxygen. Plants grown at a low light intensity (65 μE m−2s−1) lost 95% of their capacity to increase nitrate reductase activity, while plants grown at 195 μE m−2s−1retained 80% of their nitrate reducing capacity after 6 h chilling pretreatment in the 250 μE m−2s−1light. Previously induced nitrate reductase activity was also affected by light during chilling. A lag phase of 7 h preceded a fast phase of decrease in activity. Both in vivo and in vitro activity decreased to 15% of the control value after 18 h of chilling in the light. It is concluded that the induction mechanism of nitrate reductase is primarily affected by photooxidation during chilling. The decrease in nitrate reductase activity is attributed to a decrease in the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00701.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The dormancy breaking effect of sodium azide was studied in seeds of several genetically pure lines ofAvena fatuaL. isolated from field populations. Sodium azide (0.8 and 1 mM) induced germination in several dormant lines (characterized by long term dormancy) after two weeks of treatment. By about five weeks, germination was nearly complete in azide treated seeds as compared to little or no germination in controls. (2‐chloroethyl) trimethylammonium chloride (an inhibitor of gibberellin biosynthesis) completely inhibited the azide effect suggesting that stimulation of germination by azide requires gibberellin biosynthesis. Azide was very effective in breaking dormancy in lines AN‐51, AN‐86, AN‐127 and AN‐265, but failed to induce germination in Montana 73. In this line there was a synergism between azide and gibberellic acid in promotion of germination. Thus, at least two metabolic blocks are involved in the stimulation of germination in this line. Salicylhydroxamic acid (an inhibitor of alternative respiration) at 3 mMcompletely inhibited the germination induced by 1 mMazide. At this concentration, salicylhydroxamic acid did not inhibit germination in 1) genetically nondormant seeds (line SH‐430), 2) afterripened seeds of a dormant line (AN‐51), and 3) gibberellic acid‐treated dormant seeds. These findings suggest that salicylhydroxamic acid‐sensitive process(es), presumably alternative respiration, is necessary for the stimulation of germination in the presence of azide, but not in the germination of genetically nondormant, gibberellic acid‐treated dormant, or

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00702.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Embryos ofHaplopappus gracilis(Nutt.) Gray were prehydrated in water or under different conditions, all of them inhibiting or greatly reducing embryo elongation (abscisic acid, polyethylenglycol, cycloheximide, cordycepin, aminophylline, and at 4°C), dehydrated for 24 h and regerminated. All treatments resulted in improved drought resistance compared with water controls, but the best results were obtained with pretreatment with abscisic acid. In fact these embryos revealed in the rehydration phase, (a) the highest percentage of embryos able to resume germination, (b) the lowest leakage of ninhydrin reacting substances, and (c) the highest level of14C‐leucine incorporation. Lengthening of the prehydration phase in abscisic acid up to 24–48 h improved the conditions of the embryos in the rehydration phase, with less damage to the cells of the radicle tip. A protective action of abscisic acid, possibly at the level of the cell membrane system, is hypothes

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00703.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The movement of 2‐14C‐abscisic acid applied to a mature leaf of broad‐bean plants (Vicia fabaL. cv. Aguadulce) was investigated by liquid scintillation counting and autoradiography. The radioactivity was readily transported into the whole plant by the phloem after 90 min. Thereafter, radioactivity moved towards the upper part of the plant, where it accumulated in the young growing leaves and in the apical bud. During transport, 2‐14C‐ ABA was slightly metabolized, and a subsequent rapid metabolism occurred in the young leaves of the apical part of the plant and in the axillary buds released from apical dominance in decapitated plants. Transport of exogenous ABA from the apical bud presented the characteristics of a diffusion

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00704.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Endogenous levels of abscisic acid (ABA) were measured by gas‐liquid chromatography (electron capture) in stems and axillary buds of intact or decapitated broad‐bean plants (Vicia fabaL. cv. Aguadulce). Endogenous ABA was distributed in the main axis according to a concentration gradient from the apical part of the stem towards the base. Axillary buds contained ABA levels which were from 4 to 9 times higher than those in the corresponding nodes and internodes. Decapitation of the plant was followed within 6 h by a large decrease of ABA levels in all the parts of the main axis. The diminution of ABA content was the most important in axillary buds released from apical dominance. Twenty‐four hours after the decapitation, the ABA concentration further decreased in the upper parts of the stem, while no modification was observed in the basal parts of the stem containing the smallest levels o

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00705.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY