摘要:

Maize (Zea maysL. Hybrid Sweet Corn, Royal Crest), a C4plant, was grown under different light regimes, after which the rate of photosynthesis and activities of several photosynthetic enzymes (per unit leaf chlorophyll) were measured at different light intensities. Plants were grown outdoors under direct sunlight or 23% of direct sunlight, and in growth chambers at photosynthetic photon flux densities of about 20% and 8% of direct sunlight. The plants grown under direct sunlight had a higher light compensation point than plants grown under lower light. At a light intensity about 25% of direct sunlight, plants from all growth regimes had a similar rate of photosynthesis. Under saturating levels of light the plants grown under direct sunlight had a substantially higher rate of photosynthesis than plants grown under the lower light regimes. The higher photosynthetic capacity in the plants grown under direct sunlight was accompanied by an increased activity of several photosynthetic enzymes and in the amount of the soluble protein in the leaf. Among five photosynthetic enzymes examined, RuBP carboxylase (EC 4.1.1.39) and pyruvate, Pi dikinase (EC 2.7.9.1) were generally just sufficient to account for rates of photosynthesis under saturating light; thus, these may be rate limiting enzymes in C4photosynthesis. Pyruvate, Pi dikinase and NADP‐malate dehydrogenase (EC 1.1.1.82) were the only enzymes examined which were light activated and increased in activity with increasing light intensity. In the low light grown plants the activity of pyruvate, Pi dikinase closely paralleled the photosynthetic rate measured under different light levels. With the plants grown under direct sunlight, as light intensity was increased the activation of pyruvate, Pi dikinase and NADP+‐malate dehydrogenase proceeded more rapidly than photosynthe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02819.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A photosynthetic apparatus is present in the epidermis of the bottom zone of the pitcher ofSarracenia purpureaL. ssp.purpurea.This has been demonstrated using conventional light and electron microscopy, as well as fluorescent and immunohistochemical techniques. Red intrinsic fluorescence by these chloroplasts indicates photochemical activity. Antibodies against the coupling factor of chloroplast ATPase and against the subunits of ribulose‐bis‐phosphate‐carboxylase were bound to the epidermal chloroplasts. This has been visualized using a ferritin‐isothiocyanate labeled second antibody. These results unequivocally prove the existence of the two main proteins which are associated with the photophosphorylation (membrane protein) and carbon dioxide fixation (stromal protein). The possible implication of this system to interrelationships between the carnivorous plant and aquatic insects inhabiting its leaves is di

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02820.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Cytokinins in the different regions of Cuscuta reflexa Roxb. vine have been extracted and assayed using theXanthiumcotyledon bioassay with N6‐benzylaminopurine as the reference cytokinin. Maximum cytokinin level was found in the haustoria‐bearing region with the gradient decreasing towards the apex. The cytokinin content of the apex was less than 1% of that in the whole haustorial region. Interestingly, the concave half of the vine contained about forty times more cytokinin in the haustorial region than the corresponding convex half. The high concentration of cytokinin or cytokinin‐like substances in the haustoria‐bearing site inCuscutamight be due either to a high RNase activity in the region or translocation from the host to parasite

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02821.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Light‐ and benzyladenine‐induced reversal of the changes in chlorophyll content and catalase activity were studied in the attached first leaf ofOryza sativaL. cv. Bala, kept in darkness for different periods before maturation. Dark treatment caused a decrease in chlorophyll content and catalase activity at all times. Light treatment of dark‐incubated seedlings at different periods before maturation reversed the dark‐induced effect on chlorophyll content, catalase activity and dry weight and also caused a further rise in chlorophyll content compared to initial values. In darkness, the application of benzyladenine replaced the light effect in maintaining catalase activity. Chlorophyll content was also maintained by initially applied benzyladenine. Benzyladenine did not promote the photoinduced maintenance and increase in chlorophyll content and catalase activity at any time. Treatment with hydrogen peroxide, glycolate and amizol resulted in an accelerated chlorophyll breakdown and had varied effects on catalase levels. Chlorophyll decrease due to peroxide accumulation was to some extent reversible by benzyladenine, but the hormone had no effect on the peroxide‐induced decrease in catalase activity. Development of catalase is light dependent. Benzyladenine stabilises the enzyme but has no effect on its

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02822.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Analysis of total nitrogen, chlorophyll content, ribulose‐1,5‐bisphosphate carboxylase/oxygenase activity and net photosynthesis rate was carried out on the leaves that support the developing pods in pigeon pea [Cajanus cajan(L.) Millsp. cv. Prabhat] at several stages during pod filling. A continuous loss in all the above‐mentioned parameters was observed during the course of pod development. When no pods were allowed to develop by continuous flower removal treatment, there was a considerable delay in loss of all these metabolic parameters. Excision of pods after their mid‐development resulted not only in no further loss, but also in a significant recovery both of total nitrogen and of other investigated characte

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02823.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

InAllomyces arbusculaButl., strain Bali, the ratio of protein to dry weight remained constant in exponentially growing but decreased in differentiating cultures. The adenylate pools (ATP, ADP, AMP) and energy charge which integrates them, increased during zoospore germination and stabilized around 0.9 during differentiation. The level of ATP increased early during the induction of zoosporangia for up to 1 h and then declined. The ADP and AMP remained low for most of the time except for a transient increase in ADP (first 30 min induction). The energy charge was low in spores. The rate of turnover of proteins during growth and differentiation was more or less similar for up to 1.5 h after transfer. Subsequently very little turnover of proteins occurred in the growing plants. In differentiating plants, the rate of degradation was maintained and by the end of the 4 h experimental period 30% of the vegetative proteins were degraded. The intracellular ammonium showed a peak between 30 to 60 min of induction and was higher in the differentiating mycelia than in actively growing plants, while the glutamate pool remained around 1 μmol (mg protein)−1in both types of plants. The physiological role of these protein degradation products is discuss

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02824.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

In the tomato (Lycopersicon esculentumL.) mutant ‘chloronerva’ the biosynthesis of nicotianamine, a derivative of the amino acid azetidine‐2‐carboxylic acid, is blocked. Application of nicotianamine to leaves of seedlings of the mutant reduced the abnormally high iron content of the plants to the level of the wild‐type. In short‐term experiments nicotianamine decreased the amount of iron removed from the nutrient medium by isolated roots of both wild‐type and mutant. Addition of nicotianamine to the nutrient solution at 10−5Minhibited the excessive iron uptake by the mutant and wild‐type. This effect was more evident with59Fe‐ethylenediamine‐N, N′‐bis‐(o‐hydroxyphenylacetic acid) than with59FeCl3as the iron source. It is concluded that nicotianamine plays a direct or indirect role as a regul

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02825.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Filaments ofAnabaena variabilisKütz strain ATCC 29413 grown in the absence of nitrate contain nitrate reductase that is active in permeabilized filaments, but not in intact, living filaments until they have been incubated for about 40 min in the presence of nitrate. The delayed acquisition of the ability to reduce nitrate is insensitive to chloramphenicol. Thus, switching on of enzyme activity in the presence of nitrate does not involve protein synthesis and nitrate reductase activity is not regulated by the amount of enzyme present

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02826.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Germination of the polymorphic seeds and seedling growth ofAtriplex triangularisunder various salinity, gibberellic acid and kinetin treatments were determined. Gibberellic acid (GA3; 2.9 mM) promoted germination and growth at high NaCl concentrations (345 mM). Kinetin (4.7 μM) stimulated germination at all salinities and seed sizes tested. GA3and kinetin generally increased seedling growth at all concentrations of salinity studied. Higher concentrations of kinetin were found to be inhibitory

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02827.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Citrus (Citrus sinensisL. Osbeck) leaf explants completely abscise within 48 h when exposed to saturating amounts of ethylene at 25°C. When 2,5‐norbornadiene was added, 2000 μl 1−1reduced abscission of explants also exposed to 2 μl 1−1of ethylene to the level of the control, and 8000 μl 1−1reduced abscission in explants exposed to 10 μl 1−1of ethylene to the level of the control, but abscission was complete when 1 000 μl 1−1of ethylene was used in the presence of 8 000 μl 1−1of 2,5‐norbornadiene. When explants were exposed to 2 μl 1−1of ethylene, 2000 μl 1−1of 2,5‐norbornadiene prevented abscission if applied up to 10 h after exposure to ethylene. After 18 h, applied 2,5‐norbornadiene had little effect on abscission at 48 h. A Lineweaver‐Burk plot gave a 1/2 maximum value of 0.12 μl 1−1for ethylene on abscission, 2,5‐Norbornadiene gave competitive kinetics with respect to ethylene with a K1value of approximately 120 μl 1−1of 2,5‐norbornadiene. The presence of 2,5norbornadiene stimulated ethylene production, which progressively increased as the 2,5‐norbornadiene concentration was increased from 250 to 8 000 μl 1−12,5‐Norbornadiene also suppressed the induction of cellulase and polygalacturonase by ethylene. Together, 2,5‐norbornadiene and 2,4‐dichlorophenoxyacetic acid were more effective than either alone in reducing abscission. 2,5‐Norbornadiene also was effective in preventing the reduct

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1985.tb02828.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY