摘要:

An action spectrum for light induced carotenogenesis inVerticillium agaricinum(Link) Corda (ATCC 24668) was obtained by exposing mycelial pads to monochromatic radiation. Action maxima occurred at 290 (main peak) and 390 nm, and there was a minor peak at 483 nm. The results also showed interaction between the blue and UV light. Blue light partly reversed the UV light induction of carotenogenesis when given after, but not when given before UV light. This implies that there are at least two photoreceptors involved in carotenogenesis inVerticillium, but phytochrome is not likely to be one of them.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00252.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The growth rate of mung bean epicotyls was used for evaluating the effect of brassinolide on cell elongation. Growth above that of control plants was observed at 10−10Mand above. Gibberellic acid showed an additivity relationship with low concentrations (10−9–10−8M) of brassinolide in this test system and the two growth promoters may therefore act independently at the cellular level. Because of relative ease of operation, great sensitivity and the short time required for assessing biological activity, this assay could be used in conjunction with the bean second internode bioassay for evaluating the activity of brassinolide and its analogs, as well as of other growth pr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00253.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The 3,5‐dinitrosalicylic acid (DNS),o‐toluidine, and glucose oxidase methods accurately measured concentrations of standard glucose solutions in the absence of the starch hydrolyzing enzymes Diazyme (amyloglucosidase) and Clarase (α‐amylase). In the presence of high enzyme concentrations, particularly at low glucose concentrations, glucose oxidase ando‐toluidine somewhat underestimated standard glucose concentrations while DNS overestimated the glucose concentration by 100%. DNS also overestimated glucose in hydrolysates of standard potato starch. Glucose recovery was estimated at almost 200% of that given by glucose oxidase when enzyme starch weight ratios were 9:1 or more. Glucose was underestimated byo‐toluidine in starch hydrolysates in the presence of Diazyme at high enzyme‐starch weight ratios. DNS similarly overestimated glucose in starch hydrolysates from white spruce (Picea glauca(Moench.) Voss) and some other species, as enzyme‐starch weight ratios increased. Theo‐toluidine and glucose oxidase reactions were more reliable. Overestimation of the DNS reaction was not improved by treating the glucose‐enzyme solutions with anion or cation exchange resins or by removing the enzyme pr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00254.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Effects of jasmonic acid, methyl jasmonate and ABA on cytokinin‐induced soybean (Glycine maxMerrill cv. Kingen No. 1) callus growth and radish (Raphanus sativusL. cv. Comet) cotyledon growth were studied. Jasmonic acid and methyl jasmonate were powerful inhibitors of kinetin‐ or N‐phenyl‐N′‐(2‐chloro‐4‐pyridyl)urea‐induced soybean callus growth, the former being more effective than the latter, especially at low concentrations (0.45 to 4.5 μM). These compounds could completely eliminate kinetin‐ or N‐phenyl‐N′‐(2‐chloro‐4‐pyridyl)urea‐induced soybean callus growth at 45 μM. At low concentrations ABA had no effect but at 450 μMit completely eliminated callus growth induced by kinetin. Of the compounds tested ABA was the most powerful inhibitor of radish cotyledon growth in the presence or absence of kinetin. Jasmonic acid and methyl jasmonate were much less

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00255.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Superoxide dismutase (SOD) is present in the fronds ofLemna gibbaL. Differential centrifugation showed that ca. 90% of the enzyme is present in the 140,000gsoluble cell fraction.LemnaSOD is sensitive to cyanide and is probably a Cu‐Zn metallo‐protein. Gel filtration showed the SOD to have a mass of 31,000 daltons. In Zn‐defizient culture media, the activity ofLemnaSOD was less than in fronds grown in complete nutrient media whereas in Cu‐deficient media little change was found in the enzyme activity. The SOD activity in Zn‐deficient plants could be partly restored to the level of Zn‐sufficient fronds by adding Zn2+to the enzyme ass

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00256.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

During temporary incubation at 25°C in buffered solutions (pH 4.0) of abscisic acid (ABA) seeds of lettuce (Lactuca sativaL. cv. Olof) lost the red‐light initiated ability to germinate in buffer. The development of secondary dormancy required an inhibitory ABA content in the seeds during a number of days. A temporary incubation in ABA during 24 h met these requirements only if the solution was about 100‐fold more concentrated than during continuous incubation. Studies with 2‐14C‐ABA showed that the amount of ABA which had penetrated in 24 h was reduced by a factor 100 within 3 to 4 days during subsequent incubation in buffer. Both leaching and metabolic changes were involved in the reduction process. The nature of the metabolic products remained obscure. A shift to 2°C after incubation in ABA prevented the induction of secondary dormancy, but inhibited ABA metabolism. ABA did not interfere with the induction rate of secondary dormancy, and it was not required to maintain the state of dormancy. The sole function of ABA was the non‐specific inhibition of germination, which indirectly facilitated the development of an ABA independent secondary dormancy. – The level of endogenous ABA was compared to the amount of ABA found in the embryo during and after incubation in ABA solutions marked with 2‐14C‐ABA. The level of endogenous ABA in air‐dry seeds (0.11 ng/mg dry weight) corresponded to the minimal level at which penetrated ABA inhibited germination. This level had to be present at least during 4 to 5 days to inhibit the effect of red light. Since endogenous ABA was quickly reduced upon imbibition, a regulatory function of endogenous ABA in the inhibition of red light induced germination can be ruled out. A function in the temporary inhibition of dark germination and, consequently, in the development of secondary light irresponsiveness cannot b

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00257.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Submitochondrial particles (SMP) were produced from Jerusalem artichoke (Helianthus tuberosusL.) mitochondria by sonication and differential centrifugation. The SMP were about 50% inside‐out as measured by the access of reduced cytochromecto cytochromecoxidase. Uncoupled NADH oxidation (1 mMNADH) by the SMP was 120 nmol O2min−1mg−1, which was reduced to 98 nmol O2min−1(mg mitochondrial protein)−1in the presence of EGTA. In contrast, the oxidation of NADH by intact mitochondria was completely inhibited by EGTA (from 182 to 14 nmol O2min−1mg−1). The EGTA‐resistant NADH oxidation by the SMP is ascribed to the NADH dehydrogenase(s) on the inside of the inner membrane and exposed to the medium in the inside‐out SMP. In the presence of EGTA it could be shown that two NADH dehydrogenase activities were present in the SMP. One had an apparent Kmof 7 μMfor NADH, a Vmaxof 80 nmol NADH min−1mg−1, and was rotenone‐sensitive. This dehydrogenase is equivalent to the mammalian Complex I NADH dehydrogenase. The other dehydrogenase, which was rotenone‐resistant, had a Kmof 80 μMand a Vmaxof 131 nmol NADH min−1mg−1; it is probably responsible for the rotenone‐resistant oxidation of organic acids often observed in plant mitochondria. The redox poise of the pyridine nucleotides had only a small effect on the relative rates of the two internal dehydrogenases. Electron flow through these dehydrogenases appears, therefore, to be regulated mainly by the concentration of NADH

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00258.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The acclimation of the net flux density of CO2to temperature, and the effects of freezing‐stress on the functional integrity of photosynthesis were compared forBetula tortuosaandBetula pubescens. Single expanded leaves ofB. tortuosahad a higher rate of net photosynthesis and a greater capacity to acclimate to a low growth temperature regime than had leaves ofB. pubescens. At low temperatures, stomatal conductances were higher forB. tortuosathan forB. pubescens. In neither species were the stomatal conductances determining the decrease of the rate of net photosynthesis at low temperatures. There was a marked difference between leaves of the two species in their ability to withstand freezing, as revealed by measurements of changes in temperature‐induced variable fluorescence. The chloroplast thylakoids ofB. tortuosawere better able to maintain their functional integrity at sub‐zero temperatures than were those ofB. pube

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00259.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The kinetics of daily photosynthesis, transpiration and dark respiration of shoots of maize plants (Zea maysL.) were studied in a growth chamber. After one or two days of reduced light intensity, the photosynthesis and the transpiration returned immediately to a level higher than expected. Respiration, which was reduced by at least 50%, returned slowly for over 2 days towards the initial level. These results suggest the existence of reserves of assimilation products which are used up while maintaining the growth of the aerial part in spite of the lack of assimilation. The prolonged reduction of the respiration shows that it is not strongly correlated to photosyntheis or to growth but rather to the amount of available reserves of assimilate.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00260.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Studies were conducted with radio‐labeled indole‐3‐acetic acid ([2‐14C] IAA) and tobacco callus culture (Nicotiana tabacumL. cv. White Gold) to investigate the mode of action of the herbicide glyphosate (N‐phosphonomethylglycine). The tissue was first grown with or without glyphosate for 1 to 14 days and then incubated with [2‐14C] IAA for 4 h. Metabolism of [2‐14C] IAA in the tissue was studies by solvent fractionation, high performance liquid chromatography and liquid scintillation counting. The tissue grown with 0.2 mMglyphosate had low level of free [2‐14C] IAA and high levels of other fractions containing metabolites and conjugates of the labeled IAA. After 1 day of glyphosate treatment the free [2‐14C] IAA level in the tissue was reduced by 77% compared to that of the control; after 10 days of treatment the decrease was 96%. The decrease in the free [2‐14C] IAA level was not due to inhibition of IAA uptake, but due to enhanced rates of oxidation and conjugate formation of IAA. The increased oxidation of IAA in the treated tissue was not due to a direct effect of glyphosate on IAA‐oxidase since glyphosate was inactive on IAA oxidation in a cell‐free system in vitro. The glyphosate‐induced growth inhibition was partially overcome by addition of 1 μM2,4‐dichlorophenoxyacetic acid to the medium. The results lead to the conclusion that glyphosate inhibits growth by depletion of free IAA through rapid acceleration of both conjugate formation and

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb00261.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY