摘要:

This study determined how surgical removal of the stem terminal, with indole‐3‐butyric acid (IBA) treatment, influenced concentrations and partitioning of carbohydrates inPinus banksianaLamb, cuttings during propagation. Seedlings and cuttings that originated from 90‐day‐old stock plants were untreated or treated by removing the stem terminal, followed by application of IBA to the severed apical or basal (cuttings only) stem. Fresh and dry weights of the basal 1‐cm stems of cuttings were determined daily for the first 10 days of propagation (i.e., before roots were visible). In addition, basal 1‐cm stems, upper (ca 9‐cm) stems and needles of seedlings and cuttings were analyzed for sucrose, soluble reducing sugar and total non‐structural carbohydrate. Net concentrations of each carbohydrate in cuttings were obtained by subtracting corresponding concentrations for similarly treated seedlings, yielding data directly related to only the physiology of rooting. Data for cuttings indicated that presence of the stem terminal combined with applied IBA positively influenced rooting through processes that increased basal stem fresh and dry weights before root emergence. Removal of the stem terminal influenced accumulation of net total carbohydrate in cuttings, but the major effect was on carbohydrate partitioning. Either type of IBA treatment after removal of the stem terminal usually resulted in different net carbohydrate concentrations in each tissue source of cuttings, compared with only removal of the terminal. Neither basal nor apical IBA treatment of cuttings without stem terminals yielded results for carbohydrate accumulation and partitioning like those obtained with intact cuttings. Removal of the stem terminal, even if followed by IBA treatment, may have lessened rooting potential of cuttings because it resulted in greater reducing sugarstarch concentration ratios in basal stems compared with those in

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04966.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Three levels of atmospheric CO2and 2 levels of relative humidity (RH) during the rooting period were tested for their effect on several factors presumed to influence adventitious root formation in leafy pea (Pisum sativumL. cv. Alaska) cuttings. Compared to normal CO2levels (350 μl l−1), neither 1800 nor 675 μl l−1CO2affected the rooting percentage or the number of roots per cutting. However, 1800 μl l−1CO2increased root and shoot dry weight, root length, carbohydrate levels in the base of the cuttings and water potential (Ψw) of cuttings compared to normal levels of CO2. Compared to 87% RH. 55% RH decreased all of the above parameters, including the number of roots per cutting. A polyvinyl chloride antitranspirant (which partially blocks stomata and slows photosynthesis) applied simultaneously with 87% RH increased Ψwand root length but lowered all of the other above parameters, compared to 87% RH without antitranspirant. Increasing current photosynthate (products of photosynthetic activity after excision), carbohydrate, or Ψweither alone or together was associated with increased root system size but not necessarily with increased rooting percentage or root number. The data are consistent with a hypothesis that the number of roots per cutting increased with increasing current photosynthate and carbohydrate until some other factor became limiting. Also, the effect of Ψwon rooting percentage and root number was mediated through its effect on current photosynthate and

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04967.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Proliferating cultures ofActinidia deliciosaA. Chev., C. F. Liang and A. R. Ferguson cv. Tomuri (♂) were grown under photosynthetic photon flux density (PPFD) rates ranging from 30 to 250 μmol m−2s−1in order to determine certain physiological parameters in vitro: CO2evolution, photosynthesis at three CO2atmospheric concentrations (330, 1450 and 4500 μl l−1), fresh and dry matter accumulation and proliferation rate.A proportional response in dry weight, dry/fresh weight ratios and PPFD was found. The proliferation rate increased up to 120 μmol m−2s−1but decreased at higher rates. At the highest PPFD, the CO2released from cultures and accumulated in the vessels reached 200 μl l−1of; at the lowest rate the CO2concentration reached 10500 μl l−1after 28 days of culture. The photosynthetic rate at 1450 and 4500 μl l−1of CO2was nearly 4 times higher than at the lowe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04968.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The plant plasma membrane contains a 1,3‐β‐glucan synthase (EC 2.4.1.34) which has its active site on the cytoplasmic side of the membrane, while the product, the cell wall component callose, is deposited on the apoplastic side of the membrane. This enzyme should therefore be an integral, transmembrane protein. The activity of the enzyme is stimulated by Ca2+, polyamines, and polyols. Using sealed, inside‐out (cytoplasmic side out) plasma membrane vesicles from sugar beet (Beta vulgarisL.) leaves, which permits the activity to be measured without solubilization of the membrane, we have localized the activator sites for Ca2+, spermine, and cellobiose to the cytoplasmic side of the plasma me

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04969.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

One‐year old loblolly pine (Pinus taedaL.) seedlings were grown in an unshaded greenhouse for 7 months under 4 levels of ultraviolet‐B (UV‐B) radiation simulating stratospheric ozone reductions of 16, 25 and 40% and included a control with no UV‐B radiation. Periodic measurements were made of growth and gas exchange characteristics and needle chlorophyll and UV‐B‐absorbing‐compound concentrations. The effectiveness of UV‐B radiation on seedling growth and physiology varied with the UV‐B irradiance level. Seedlings receiving the lowest supplemental UV‐B irradiance showed reductions in growth and photosynthetic capacity after only 1 month of irradiation. These reductions persisted and resulted in lower biomass production, while no increases in UV‐B‐absorbing compounds in needles were observed. Seedlings receiving UV‐B radiation which simulated a 25% stratospheric ozone reduction showed an increase in UV‐B‐absorbing‐compound concentrations after 6 months, which paralleled a recovery in photosynthesis and growth after an initial decrease in these characteristics. The seedlings grown at the highest UV‐B irradiance (40% stratospheric ozone reduction) showed a more rapid increase in the concentration of UV‐B‐absorbing compounds and no effects of UV‐B radiation on growth or photosynthetic capacity until after 4 months at this irradiance. Changes in photosynthetic capacity were probably the result of direct effects on light‐dependent processes, since no effects were observed on either needle chlorophyll concentrations or stomatal conductance. Further studies are necessary to determine whether these responses per

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04970.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Antiserum raised against the LiCl extract of maize shoot cell walls suppresses auxin‐induced elongation of maize coleoptile segments. A series of polyclonal antibodies were raised against protein fractions separated from the LiCl extract of maize (Zea maysL. cv. B73 x Mo17) coleoptiles by SP‐Sephadex and Bio‐Gel P‐150 chromatography. To understand the role of cell wall proteins in growth regulation, the effect of these antibodies on auxin‐induced elongation and changes in the cell walls of maize coleoptiles was examined. Four of the fractions prepared reacted with the antiserum raised against the total LiCl extract and effectively suppressed its growth‐inhibiting activity. Only these fractions contained the proteins responsible for eliciting growthinhibiting antibodies. The antibodies capable of growth inhibition of auxin‐induced elongation of segments also inhibited auxin‐induced cell wall loosening (decrease in the minimum stress‐relaxation time of the cell walls) of segments. The antibodies raised against one of the protein fractions separated by SP‐Sephadex inhibited the autolytic reactions of isolated cell walls and the auxin‐induced decrease in (1→3), (1→4)‐β‐D‐glucans in the cell walls. Thus, the degradation of β‐D‐glucans by cell wall enzymes may be associated with the cell wall loosening that is responsible for cell elongation. Because the other antibodies did not influence the auxin‐induced degradation of (1→3), (1→4)‐β‐D‐glucanses, β‐D‐glucanases and other cell wall enzymes may cooperat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04971.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The qualitative distribution and quantitative estimates of nitrogenase (EC 1.7.99.2), glutamine synthetase (EC 6.3.1.2), phycoerythrin and ribulose 1,5‐bisphosphate carboxylase/oxygenase (EC 4.1.1.39) were studied in the cyanobacteriumNostocresiding in internal cephalodia of the tripartite lichenNephroma arcticumL. Polyclonal antisera, raised in rabbit against the proteins, and goat anti‐rabbit IgG conjugated to 10 nm gold were used as probes to detect the antigens by transmission electron microscopy. Western blot analyses demonstrated the monospecificity of the antisera. Nitrogenase was localized in heterocysts, with vegetative cells showing a label intensity comparable to the background. Distribution of the antigen within the heterocysts was uniform. Glutamine synthetase labelling was very low, but appeared to be distributed in both cell types. An intense phycoerythrin labelling was associated with the thylakoid region of the vegetative cells, whereas a much lower labelling was observed in the heterocyst. No significant differences were found between cyanobionts in younger and older cephalodia except for the nitrogenase labelling, which was higher in heterocysts of the cyanobiont in younger cephalodia. Most of the ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) label was present in vegetative cells. The Rubisco label was pronounced in the carboxysomes, whereas the label in the cytoplasm, on a unit area basis, was much lower. Heterocysts showed a label intensity similar to that of the vegetative cell cytoplasm. InNostocof the bipartite lichenPeltigera caninaL., the Rubisco protein showed a comparable distribution pattern, but the average number of carboxysomes per vegetative cell was about 4 times h

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04972.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Putrescine uptake and translocation were studied by feeding [3H] putrescine to roots of tomato seedlings (Lycopersicon esculentumMiller, cv. Earlypak 7) at the stage of expanded cotyledons, of maize seedlings (Zea maisL.) at the coleoptile stage, and of one year old pines (Pinus pineaL.). Putrescine translocation was rapid as radioactivity appeared in the upper part of the seedlings within 30 min, continuing to increase up to 24 h, while it decreased in roots. The putrescine supplied was partly metabolized to spermidine and spermine in the course of 24 h. The transport was temperature‐dependent as it increased with increasing temperature from 4°C to 30°C. In plants kept in 100% relative humidity the transport decreased by 27% compared to controls kept in 50% relative humidity. The existence of basipetal transport was assessed by feeding labeled putrescine to cotyledons or to a primary leaf of tomato plants at different stages of growth. The influence of ringing at the hypocotyl level on polyamine translocation in pine plants was studied in order to exclude cortical parenchyma and phloem from transport. Radioactivity decreased in the hypocotyl just above the ring and in the upper parts (epicotyls with needles), but long‐distance transport was low affected indicating xylem transport. It is suggested that polyamine transport is not polar, and that it occurs mainly through xylem ve

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04973.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Leaves of soybean (Glyxine max.L., var. Progress) were subjected to desiccation, which brought about varying degree of membrane damage as checked with the conductivity method. Progress of injury up to 30% was associated with promotion of ethylene synthesis and with accumulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) and 1‐(malonylamino)cyclopropane‐l‐carboxylic acid (MACC) in the cells, as well as with activation of lipoxygenase, the enzyme which is involved in lipid peroxidation and which is capable of forming activated oxygen. The stress‐induced promotion of ethylene synthesis was inhibited by the ACC synthase inhibitor aminooxyacetate (AOA). as well as by n‐propyl gallate (PG), a free radical scavenger and inhibitor of lipoxygenase. Pretreatment of non‐stressed soybean leaves with different concentrations of PG also resulted in the corresponding inhibition of lipoxygenase activity and ethylene formation, the former effect being less pronounced than the latter one. In the tissues pretreated with propyl gallate, the ACC level was not affected, whereas the MACC substantially increased. In leaves showing 40% membrane damage neither lipoxygenase activity nor ethylene synthesis increased any further, despite a further increase in the ACC and MACC levels. Therefore, we propose that there are two prerequisites for effective in vivo synthesis of stress ethylene: promotion of ACC synthesis and activation of a free radical‐generating system, which is responsible for the non‐enzymatic conversion of ACC to ethylene. The latter effect seems to be due to the activation of the membrane‐associated lipoxygenase, which depends on stress‐induced alteratio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04974.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The development of mitochondrial NAD+‐malate dehydrogenase (EC 1.1.1.37) in mung bean and cucumber cotyledons was followed. using the antibody raised against it, during and following germination. The developmental patterns were quite different between the two. In cucumber, the content of mitochondrial malate dehydrogenase continued to increase through 3–4 days after the beginning of imbibition. This was, at least in part, due to active synthesis of the enzyme protein, and the synthesis seemed to be regulated by the availability of the translatable mRNA for the enzyme. In mung bean, on the other hand, the enzyme was present in dry cotyledons at a rather high concentration, and remained at a constant level between day 1 and day 3 after the reduction of the content to one‐half its initial level during the first day. De novo synthesis of the enzyme could not be detected in mung bean cotyledons by pulse‐labeling exp

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb04975.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY