摘要:

The cytochrome composition of plasma membranes (PM) obtained by phase partitioning of microsomal fractions from spinach leaves (Spinacea oleraceaL. cv. Medania), cauliflower inflorescences (Brassica oleraceaL.), sugar beer leaves (Beta vulgarisL.) and barley (Hordeum vulgareL. cv. Kristina) roots and leaves was characterized by absorbance difference spectrophotometry at different reducing conditions at 20 and – 196°C, by redox titration, and by heme staining of polypeptide bands after lithium dodecyl sulfate polyacrylamide gel electrophoresis (LDS‐PAGE). The location of the α‐bands in the difference spectra and the loss of heme after treatment with LDS indicated that predominantly cytochromes of theb‐type were present in all species tested. The total concentration of cytochrome was ca 0.35 nmol (mg protein)−1. The main component (ca 70% of total) was completely reduced by ascorbate and partly by NADH and had a midpoint potential of ca 150 mV. At – 196°C, ascorbate reduction revealed a symmetrical α‐band at ca 557 nm with PM from spinach leaves, cauliflower and sugar beet leaves, but with barley root and leaf PM ascorbate reduction resulted in an asymmetrical α‐band (shoulder at 552, maximum at 559 nm). In the dithionite‐reduced minus ascorbate‐reduced spectrum at –196°C a split α‐band (552 + 558 nm) was seen with PM from all species. This minor component had a midpoint potential of ca – 50 mV and is probably identical to cytochromeb5, the presence of which would explain the relatively high NADH‐cytochromecreductase activities observed with plant PM. With PM from cauliflower, CO‐difference spectra indicated that cytochromesP‐420 andP‐450 were present at concentrations up to 0.06 and 0.03 nmol (mg protein)−1, respectively. Visualization of cytochromes by heme staining after LDS‐PAGE was complicated by endogenous peroxidase activity and by loss of heme during solubilisation. A presumptiveb‐cytochrome (heme‐stained band

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05621.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The inner membranes from wheat (Triticum aestivumL. cv. Walde) etioplasts were separated into membrane fractions representative of prolamellar bodies and prothylakoids by differential and gradient centrifugations. The isolated fractions were characterized by absorption‐, low‐temperature fluorescence‐, and circular dichroism (CD) spectroscopy, by high performancy liquid chromatography and by sodium dodecyl sulphate polyacrylamide gel electrophoresis.The prolamellar body fraction was enriched in NADPH‐protochlorophyllide oxidoreductase (E.C. 1.6.99.1), and in protochlorophyllide showing an absorption maximum at 650 nm and a fluorescence emission maximum at 657 nm. Esterified protochlorophyllide was mainly found in the prothylakoid fraction. The carotenoid content was qualitatively the same in the two fractions. On a protein basis the carotenoid content was about three times higher in the prolamellar body fraction than in the prothylakoid fraction. The CD spectra of the membrane fractions showed a CD couplet with a positive band at 655 nm, a zero crossing at 643–644 nm and a negative band at 623–636 nm. These results differ from earlier CD measurements on protochlorophyllide holochrome preparations. The results support the interpretation that protochlorophyllide is present as large aggregates in combination with NADPH and NADPH‐protochlorophyllide oxidoreductase in the prola

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05622.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Enzymes of the β‐oxidation pathway in rice (Oryza sativaL., cv. Arborio) coleoptiles were investigated. The coleoptiles contain acyl‐CoA oxidase (EC 1.3.99.3), 3‐hydroxyacyl‐CoA dehydrogenase (EC 1.1.1.35), enoyl‐CoA hydratase (EC 4.2.1.17) and thiolase (EC 2.3.1.9). Analysis of coleoptile homogenates by sucrose density fractionation showed a preferential distribution of these enzymes in the unspecialized peroxisomes. The enzymatic activity found in the mitochondrial fraction was due to peroxisomal contamination since electron micrographs show the peroxisomes to be intact and pure whereas the mitochondrial fraction was contaminated by other organelles. It appears that the β‐oxidation pathway is localized in the unspecialized peroxisomes of rice coleoptiles, extending the number of plant species in which such a localization has

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05623.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Between the end of blooming and the withering of petals of cut carnations (Dianthus caryophyllusL. cv. Ember), the total superoxide dismutase activity decreased. The three forms of superoxide dismutase (Cu, Zn‐SOD, Fe‐SOD and Mn‐SOD. EC1. 15. 1. 1) identified on polyacrylamide gel exhibited several isozymes, the activities of which decreased sooner or later during aging. The important activity of the Mn‐SOD decreased at the beginning of withering to become undetectable, while the weak activity of Fe‐SODs declined only at the end of withering. It is suggested that the localization of SODs in the cell may explain these differences. Hypothesis are proposed to understand the decreased activity of SODs dur

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05624.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The hypersensitive response (HR), a rapid local necrosis accompanied by the production of antimicrobial compounds, is a manifestation of the primary defense mechanisms through which plants prevent colonization by potentially pathogenic microorganisms. The pathogen factors that trigger HR‐associated defense mechanisms have yet to be established. Application of transposon mutagenesis and molecular cloning techniques have provided new insights into the bacterial elicitation of the HR. This review focuses on the interaction ofPseudomonas syringaewith non‐host plants as a model system for the bacterial induction of the HR and discusses (a) the genetics ofPseudomonas syringaepathogenicity and HR elicitation, (b) the environmental conditions controlling expression ofPseudomonas syringaepathogenicity/HR determinants, (c) the nature of the HR elicitor and (d) early plant responses to the patho

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05625.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Ross, J. J. and Reid, J. B. 1989. Internode length in Pisum. Biochemical expression of theLegene in darkness.TheLegene appears to be biochemically expressed in dark‐grown pea (Pisum sativumL.) plants since the previously reported difference in metabolism of [3H]‐GA30between light‐grownLeandLeplants was also observed in darkness. Furthermore, both light‐ and dark‐grownLeplants contained more endogenous GA1, ‐like substance than did comparableLeplants. Darkness did not appear to significantly increase the accumulation of GA1, in eitherLeorLeplants, although confirmation of GA1levels by gas chromatography‐selected ion monitoring is still required. The results support previous findings that the overall metabolism of [3H]‐GA20, is accelerated by darkness. The evidence presented here supports previous suggestions that darkness acts on internode length by increasing some aspect of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05626.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The levels of GA1, 3‐epiGA1and GA8in genotypesLe, leandledofPisum sativumL. were determined by gas chromatography‐selected ion monitoring (GC‐SIM) after feeds of [3H,13C]‐GA20to each genotype. The levels of endogenous and [13C]‐labelled metabolites were determined by reverse isotope dilution with unlabelled GA1, 3‐epiGA1and GA8. The results demonstrate a quantitative relationship between the level of GA1and the extent of elongation both on a per plant and a per g fresh weight basis. These results are consistent with previous findings in peas and other species possessing a predominant early 13‐hydroxylation pathway for GA biosynthesis.The levels of 3‐epiGA1also decreased in the genotypic sequenceLe, le, ledalthough not as rapidly as for the level of GA1. This may suggest that the alleles at thelelocus also influence the format

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05627.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The osmotic role of nitrate during aftermath growth ofLolium perenneL. cv. Réveille was investigated. Plants were grown from seed in a controlled environment using a liquid medium with 1.0 mMNH4NO3as nitrogen source.Eight‐week‐old plants were cut 4.0 cm above the root system and then harvested over a 14‐day period of regrowth on the same initial nutrient solution, except that nitrate was15N labelled. Throughout the experimental period, nitrate storage and reduction in roots were low. In stubble and especially in leaves, nitrate accumulated during the first 6 days of regrowth whereas nitrate reduction mainly occurred after this period. Analyses of carbohydrate, chloride and potassium contents in stubble and leaves showed that the accumulation of nitrate osmotically compensated for the decrease in soluble sugars during the first 6 days of regrowth.The cumulative osmotic potential of sugars, chloride and nitrate in differently treated plants was studied in stubble and leaves. Compared with uncut plants, the lower carbohydrate concentrations found in cut plants regrowing on 1.0 mMNH4NO3were compensated for by an accumulation of nitrate. During aftermath growth on low nitrogen nutrition (0.2 mMNH4NO3), chloride replaced nitrate, supporting the proposed osmotic function of nitrate.It is concluded that nitrate is involved in the osmotic adjustment of ryegrass during regrowth after c

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05628.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Phytotropins with a range of activity, chemistry and stereochemistry were used to detect the presence of the receptor for 1‐N‐naphthylphthalamic acid (NPA) in leaves, stems, roots and coleoptiles inZea maysL. cv PX‐80 through their ability to bind to the recognition site(s) on the receptor. Their ability to bind to membrane preparations from each of the tissues was found to be very similar. It is concluded that NPA receptors with similar recognition characteristics exist throughout the plant. It is suggested that the data are further evidence in favour of the proposition that NPA receptors are physiologically signif

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05629.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Respiration measured as CO2efflux was determined at various soil O2and CO2concentrations for individual, attached roots of a succulent perennial from the Sonoran Desert,Agave desertiEngelm. The respiration rate increased with increasing O2concentration up to about 16% O2for established roots and 5% O2for rain roots (fine branch roots on established roots induced by wetting of the soil) and then remained fairly constant up to 21% O2. When O2was decreased from 21 to 0%, the respiration rates were similar to those obtained with increasing O2concentration. The CO2concentration in the root zone, which for the shallow‐rootedA. desertiin the field was about 1 000 μl l‐1, did not affect root respiration at concentrations up to 2 000 μl l‐1, but higher concentrations reduced it, respiration being abolished at 20 000 μl l‐1(2%) CO2for both established and rain roots. Upon lowering CO2to 1 000 μl l‐1after exposure to concentrations up to 10000 μl l‐1CO2, inhibition of respiration was reversible. Uptake of the vital stain neutral red by root cortical cells was reduced to zero, indicating cell death, in about 4 h at 2% CO2, substantiating the detrimental effects of high soil CO2concentrations on roots ofA. deserti. This CO2response may explain why roots of desert succulents tend to occur in porous, we

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb05630.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY