摘要:

The effect of SO2on the extractable activity of ATP sulfurylase (EC 2.7.7.4.). adenosine 5′‐phosphosulfate sulfotransferase, ribulosebisphosphate carboxylase, chlorophyll, protein, sulfate, and amino acids was examined in leaves of potted grafts of beech (Fagus sylvaticaL.) treated in outdoor fumigation chambers. Addition of 0.025 and 0.075 μl SO21−1to unfiltered ambient air caused a decrease in the extractable activity of adenosine 5′‐phosphosulfate sulfotransferase to about 20 to 30% of the controls. Neither the extractable activity of ATP sulfurylase and ribulosebisphosphate carboxylase nor the content in chlorophyll, total amino acids and protein were significantly affected by SO2, but there was an increase in the sulfate content. Leaves treated with 0.075 μl SO21−1contained more alanine and cysteine and less serine than the controls. After transfer of the SO2‐treated beech trees to control chambers there was an increase in adenosine 5′‐phosphosulfate sulfotransferase activity, but no significant decre

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04207.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The decrease in extractable activity of ribuloscbisphosphate carboxylase (EC 4.1.1.39), ATP sulfurylase (EC 2.7.7.4) and adenosine 5′‐phosphosulfate sulfotransferase and the content in chlorophyll and protein was compared in leaves of cloned beech trees (Fagus sylvaticaL.) during autumnal senescence. Leaves excised at the same time but containing different amounts of chlorophyll gave extracts with correspondingly varying amounts of ribulosebisphosphate carboxylase activity. Leaves which had almost completely lost this enzyme activity contained still appreciable ATP sulfurylase and adenosine 5′‐phosphosulfate sulfotransferase activity and soluble protein. For all components determined, there was a period lasting until mid or end of October during which there was no or only a small decrease. They were then all lost rapidly from the leaves. The specific activity of ribulosebisphosphate carboxylase decreased during this phase of rapid loss, whereas it remained essentially constant for ATP sulfurylase and adenosine 5′‐phosphosulfate sulfotransferase. During this period, the mean half life of ribulosebisphosphate carboxylase was shorter than the one of ATP sulfurylase and of adenosine 5′‐phosphosulfate sulfotransferase. These experiments clearly show that ribulosebisphosphate carboxylase was preferentially lost from beech leaves during autumnal senescence as compared to ATP sulfurylase and adenosine 5′‐phosphosulfa

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04208.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Cucurbita pepoL. cv. Trailing Marrow is monoecious, bearing separate male and female flowers and the first functional flowers are usually male. Treatment with 300 ppm ethephon delayed and greatly reduced male flower production and also increased female flower numbers. When plants were sprayed with aminoethoxyvinylglycine (AVG) no female flowers were produced but male flower production was unaffected. Even when ethephon was applied to AVG‐treated plants there was still complete inhibition of female flower production. Similarly, AVG‐treated plants subsequently exposed to 4000 ppm ethylene for two days never produced female flowers. AVG inhibits the penultimate stage in ethylene biosynthesis i.e. immediately before 1‐aminocyclopropane‐1‐carboxylic acid (ACC). Although spraying AVG‐treated plants with ACC did not reverse the inhibition, application of ACC via a cut petiole for a 72 h period following AVG application did cause female flowers to form. The evidence indicates that ACC and not ethylene is the factor controlling female flower productio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04209.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The (C2H4+ H2(C2H2))/15N2ratios of 15 clover‐Rhizobiumsymbionts. soybean, and black medick symbionts were measured. Relative efficiency based on the C2H4 production and on15N2incorporation were compared, and in most symbionts there was little difference between the two measures of relative efficiency. Total measurable electron flux through nitrogenase during acetylene reduction and15N2incorporation were nearly equal for most symbionts studied. The relative efficiency and the (C2H4+ H2(C2H2))/15N2ratio showed an inverse correlation. Use of this ratio appears preferable to use of the ratio of C2H2 reduction/N2reduction. Some evolution of H2was observed in the presence of C2H

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04210.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Germination studies were carried out with seeds ofSpergularia marinaL. Griseb produced over an interval of six months (June‐November). The response of the seeds to light and dark, various constant and alternating temperature regimes, and salinity were determined. In addition, the effects of soil moisture status at the time of seed production on the subsequent germination response of seeds were also determined. Light was an absolute requirement for germination. While a constant temperature regime did not generally favour germination of seed of any month, alternating temperature greatly enhanced germination with an optimum at 5/15°C in all seeds. When imbibed in solutions of different salinities, seeds collected in July and October behaved like true halophyte seeds whereas those collected in June. August, September and November behaved like glycophyte seeds.High concentration of gibberellic acid (3 000 μM) stimulated dark germination in the June and November seed lots, but in light, low GA3 concentration (300 μM) stimulated germination most. The addition of kinetin (30 μM) plus gibberellic acid enhanced germination in the dark in contrast to GA3 alone; kinetin alone stimulated a very low percentage germination.The moisture status of the soil at the time seeds were produced did not affect the germination response of an early seed crop (July) but affected that of the later seeds (August).Judging from the different germination responses, it appears that the seeds belong to at least two physiological groups, one which appears to need either a dark‐wet or cold‐wet pretreatmem for high germination to occur; and the other group which does not need pretreatmem. The ecological significance of these varied responses is discussed in relation to the survival of the species in it

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04211.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Senescence of rice (Oryza sativaL. cv. Jaya) leaves was regulated with kinetin and abscisic acid (ABA) sprays at the reproductive stage. The effect of such sprays on grain‐filling and yield was analyzed. Spraying 100‐day‐old plants with kinetin solution (100 μg ml‐1) significantly delayed senescence as indicated by higher total chlorophyll and protein levels in the three uppermost leaves compared with the controls. In contrast, spraying with ABA (15 μg ml‐1) significantly promoted foliar senescence. The number of spikelets per panicle, number of panicles, percentage filled grains, panicle weight and grain yield per plant and the mobilization and harvest indices were significantly increased by kinetin treatment, while ABA decreased most of them. The possibility of increased grain‐filling and thus, yield due to delayed foliar senescence by kinetin treatment and decreased grain‐filling due to hastening of senescence by A

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04212.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

After continued etiolation of oat (Avena sativaL. cv. Arnold) seedlings without greening at any stage, the volumes of both etioplasts and prolamellar bodies were found to increase to a maximum around the 9th day, declining thereafter. Throughout this process a proportion of the early lamellar components is reconverted later into prolamellar body material to account in part for this crystalline accumulation. Starch grains and stroma‐centres arc only prominent in early etioplasts. The pro‐lamellar bodies of such etioplasts are more amorphous in form resembling more closely the semi‐crystalline bodies of dark‐grown algae or light‐grown cereal seedlings. The high levels of total reducing sugars and fructans after ca 7 days of continued etiolation declined rapidly afterwards, although sucrose content was maximal on the ninth day. It is thought that these carbohydrate reserves were partly used to synthesize sterols (mainly desmethyl sterols) and carotenoids (mainly xanthophylls) found in the high concentrations on around the 9th and 10th days of continued etiolation. High levels of the steroidal saponins in etiolated primary leaves after this time declined to less than half due entirely to the disappearance of avenacoside B, which was partially converted into avenacoside A. Only traces of desgluco‐avenacosides A plus B were found in the late stages of continued etiolation. These results demonstrate that etiolated tissue changes constantly with time. Consequently, greening studies starting with etiolated tissue of different ages may differ considerably even within the sa

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04213.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Multiple forms of peroxidase with indole‐3‐acetic acid (IAA) oxidase activity were detected in callus cultures from soybean seeds [Glycinc max(L.) Merrill, cv. Acme] using ion‐exchange chromatography and polyacrylamide gel electrophoresis. The properties of the IAA oxidase were studied with a partially purified fraction eluted from a DEAE cellulose column. At pH 5.7. p‐coumaric acid and MnCl2were required as cofactors and H2O2was not able to replace them, but H2O2eliminated the usual lag period of the reaction. Activation effects obtained with some dicarboxylic acids acting only on IAA oxidase are shown. These effects were studied at different pH values and oxalic acid was found to be the most efficient activator, particularly at pH 4.6. Activation by oxalic acid occurred even in the absence of MnCl2, but the presence of this salt produced a synergistic effect. IAA oxidase showed a sigmoidal kinetic behaviour at pH 5.7 changing to hyperbolic a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04214.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Various factors affecting the yield and isolation of axenic protoplast cultures originating from Pinus pinaster root segments (in which most cells are differentiating) were studied. In spite of the use of plant material collected from germinating seeds under aseptic conditions, an additional sterilization with 0.1 % w/v mercuric chloride in 50% ethanol was a prerequisite for obtaining an axenic protoplast culture. A pretreatment with 30 mM cysteine in 0.7 M sorbitol for I h tripled the yield. Cen‐trifugation at lOOg instead of 40 g further increased the yield to 6 × 103 protoplasts per cm of root segment. Viability ranged from 80 to 91%. Cell divisions occurred after a minimum of 7 days of cultu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04215.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The soil bacteriumRhizobiuminfects its leguminous host plants in temperate regions of the world mostly by way of the growing root hairs. Root hair curling is a prerequisite for root hair infection, although sidelong root hair infections occasionally have been observed. The processes underlyingRhizobium‐induced root hair curling are unknown.Computer simulation of root hair growth indicates that one‐sided tip growth inhibition byRhizobiumcan result in root hair curling when three conditions are simultaneously fulfilled: 1) rhizobial growth inhibition is strong enough to prevent removal out of the tip growth range: 2) root hair surface growth between the attachedRhizobiumand the root hair top is inhibited; 3) rhizobial growth inhibition is limited to one side of the root hair.The results predict that root hair curling by stimulation of tip growth is improbable. This study accentuates the need for information about the growth processes contributing to tip growth in leguminous root ha

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb04216.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY