摘要:

The rhythmic growth ofGnetum africanumWelw. has an endogenous origin. Correlations between the apical bud and young leaves located at the top of the epicotyl can explain this kind of growth. Young leaves inhibit the apical bud and a prolonged inhibition leads to bud dormancy. The period of inhibition coincides with the growth of these leaves. When growth stops, dormancy is induced. Moreover a removal of young leaves suppresses inhibition which prevents dormancy induction; here again a continous suppresses inhibition which prevents dormancy induction; here again a continuous growth results. A prolonged exogenous treatment of the apical bud with abscisic acid and auxin shows that these two growth substances can play a part in the induction of dormancy after removal of the young leaves.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06332.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Manipulation of protoplasts via fusion and organelle transfer is expected to be facilitated by the technique known as electric field fusion. Construction and use are described of three flow‐through fusion chambers that incorporate flat‐sided electrodes in a manner that makes fusion of protoplasts possible througout the chambers’ total volume (4, 49 or 110 μl) under constant electrical, chemical and physical conditions.Brassica napusL. protoplasts subjected to fusogenic conditions, that is, application of voltages that induce reversible membrane breakdown, were capable not only of survival but also of cell wall resynthesis, cell division and subsequent growth and development. Intraspecific (B. napus × B. napus), interspecific. (B. napus × B. campestrisL.) and intergeneric (B. napus × Primula acaulisL.) fusion and engulfment events were followed by using on the one hand autofluorescence and fluorescein isothiocynate as respective markers or on the other hand autofluorescence and vacuolar anthocyanin (Primula). Properties and merits of flat‐sided versus cylindrical electrodes ar

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06333.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Auxin‐induced cell elongation in oat coleoptile segments was inhibited by galactose; removal of galactose restored growth. Galactose did not appear to affect the following factors which modify cell elongation: auxin uptake, auxin metabolism, osmotic concentration of cell sap, uptake of tritium‐labeled water, auxin‐induced wall loosening as measured by a decrease in the minimum stress‐relaxation time and auxininduced glucan degradation. Galactose markedly prevented incorporation of [14C]‐glucose into cellulosic and non‐cellulosic fractions of the cell wall. It was concluded that galactose inhibited auxin‐induced long‐term elongation of oat coleoptile segments by interfering with cell

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06334.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The action spectrum for polarotropism was determined, using the Okazaki large spectrograph, by brief irradiation with light between 260 nm and 850 nm in single‐celled protonemata of the fernAdiantum capillus‐venerisL., which had been cultured for 6 days in red light and then in the dark for 15 h. The action spectrum had a peak at around 680 nm. This effect was nullified by subsequent irradiaton with far‐red light, and typical red/far‐red reversibility was observed, indicating the involvement of phytochrome. Polarized ultraviolet or blue light had no effect on the direction of apical growth. The action spectrum for phototropism was also determined in the red light region by means of brief microbeam irradiation of a flank of the subapical region of the protonema. This spectrum showed a peak at 662 nm which was consistent with the absorption peak of phytochrome, but not with the peak of the action spectrum for polaro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06335.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Germination of freshly harvested seeds of a non‐dormant (ND) line (Stonehouse 319) of wild oats (Avena fatuaL.) was inhibited by incubation of the seeds at relatively high temperatures of 25 and 30°C. The germination inhibition in these seeds appeared to be a case of thermo‐inhibition which was the direct effect of hightemperature treatment (HIT), since it did not persist after transferring the seeds to an optimum germination temperature of 20°C. Even a prolonged HTT of 30°C for over 5 weeks did not prevent germination of about 80% of the seeds transferred to 20°C. However, in a significant proportion of the seeds, thermo‐dormancy was induced by 10 days of HTT at 30°C if the seeds were then incubated at sub‐optimal temperatures of 5 to 15°C. This thermo‐dormancy would appear to be ‘restrictive’ in form, since its expression was restricted to very specific conditions. Relatively low inclubation temperaturs of 5 and 10°C markedly slowed germination whether HTT was applied or not. The results suggest that thermo‐inhibition and thermo‐dormancy, induced during seasonal temperature fluctuations, may provide a survival mechanism for seeds of such ND

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06336.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Single cells were effectively released from 35–45‐day‐old soybean (Glycine maxL. cv. Yaefusanari) nodules by treatment with an enzymic solution containing 1 mg/ml maceration enzyme (Pectolyase Y‐23), 0.5Mmannitol, 2% (w/v) sucrose and 0.5% (w/v) potassium dextran sulfate. Bacteroid‐containing cells were purified by Percoll density gradient centrifugation. Electron microscopic observation showed that these cells were protoplasts enclosed by a thin wall and with well preserved internal structures including bacteroids. The single cells obtained were stable against centrifugation and vigorous pipetting. The cells retained the ability to synthesize proteins including leghaemoglobin. The ratio of leghaemoglobin components synthesized in the single cells was similar to that of components synthesized in the nodules. The bacteroidal cell fraction was further separated into three fractions by a Percoll density gradient centrifugation. Comparison of the absolute and relative leghaemoglobin content, the activity of glutamine synthetase in the cytoplasm and the activity of 3‐hydroxybutyrate dehydrogenase in the bacteroid suggests that these fractions contained cells in different stages of symbiosis. This new single cell system should provide a useful experimental system for analyzing events in the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06337.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Flowering of the long day plantHyoscyamus nigerL., which is strictly photoperiodically controlled, was induced by 58 h continuous white light. The RNA from the leaves was isolated from photoperiodically induced and non‐induced plants and the poly(A)‐rich RNA separated by affinity chromatography on oligo‐dT‐cellulose. The poly(A)‐rich RNA was translated in vitro in the presence of35S‐methionine using a rabbit reticulocyte lysate. Subsequent separation of the translation products by two‐dimensional polyacrylamide gel electrophoresis and fluorography allowed a comparison of the polypeptide pattern from induced and non‐induced leaf m‐RNA. The results indicate that induction of flowering is reflected by changes in the translation of several leaf polypeptides. These polypeptides were characterized by their isoelectric points and

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06338.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Clark L1, a normal green soybean [Glycine max(L.) Merrill] and Clark y9y9, a backross‐developed isoline exhibiting pigment deficiency, were grown under continuous red (11 W m−2and far‐red (9 W m−2) light. Chloroplast thylakoids from the unifoliolate leaf (9–10 days old) were isolated and analyzed for pigments, pigment‐protein, membrane polypeptides, electron transport and ultrastructural differences. Chloroplasts of soybean plants grown under far‐red light have decreased chlorophyllato chlorophyllbratio, increased light‐harvesting complexes, and grana structure with few stroma‐type thylakoids. Photosystem II/photosystem I ratios (PSII/PSI) are higher in far‐red due to decreased synthesis of PSI reaction center and/or less antenna

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06339.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Wheat (Triticum aestivumL. cv. Sicco) was grown for 10 days on CaSO4(0.5 mmol dm−3) and then exposed for 2 days to various nitrogenous salts in an apparatus designed to measure the exchange of O2and CO2, at constant pH and pNO3. Nitrate salts (KNO3at 0.5 and Ca(NO3)2at 0.25 and 1 mmol dm−3) caused a transient increase (40–50%) in both O2uptake and CO2release by the roots. The rate of gas exchange was nearly doubled by (NH4)2SO4(0.25 mmol dm−3). Respiration was constant in roots kept on CaSO4or given KCl. In CaSO4the content of water‐soluble sugars in roots fell by about 15% day−1. The pletion of soluble sugars was higher with NO3−and NH4+(40 and 30% day−1, respectively). At most 10 to 20% of the released CO2is involved in HCO3N−NO3−exchange and this fraction represents at most 10% of the total carbon imported or 30% of the net carbon gain by the roots. The contribution of the non‐phosphorylating “alternative” route to total root respiration was 15% in CaSO4and over 40% with NH4+In NO3−the roots respired exclusively via the cytochrome route. Increased respiration at decreased efficiency in roots of NH4+plants may be due to an overproduction of NADH. Our data support the contention that excess NADH as a “by‐product” of the formation of carboxylates in the citrate cycle can be disposed of in an alternative respira

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06340.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

High temperature stress adversely affects wheat growth in many important production regions, but the mode of injury is unclear. Wheat (Triticum aestivumL. cv. Newton) was grown under controlled conditions to determine the relative magnitude and sequences of responses of source and sink processes to high temperature stress during grain development. Regimes of 25°C day/15°C night, 30°C day/20°C night, and 35°C day/25°C night from 5 days after anthesis to maturity differentially affected source and sink processes. High temperatures accelerated the normal decline in viable leaf blade area and photosynthetic activities per unit leaf area. Electron transport, as measured by Hill reaction activity, declined earlier and faster than other photosynthetic processes at the optimum temperature of 25/15 °C and at elevated temperatures. Changes in RUBP carboxylase activities were similar in direction but smaller in magnitude than changes in photosynthesic rate. Increased protease activity during senscence was markedly accentuated by high temperature stress. Specific protease activity increased 4‐fold at 25/15 °C and 28‐fold at 35/25 °C from 0 to 21 days after initiation of temperature treatments. Grain‐filling rate decreased from the lowest to the highest temperature, but the change was smaller than the decrease in grain‐filling duration at the same temperatures. We concluded that a major effect of high temperature is acceleration of senescence, including cessation of vegetative and reproductive growth, deterioration of photosynthetic activities, and degradation of proteinace

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06341.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY