摘要:

Probes corresponding to the auxin‐inducible genesparAandparB, as well as twoauxgenes, here denotedNt‐aux8andNt‐aux16, were amplified from tobacco (Nicotiana tabacumL.) cDNA. Transcript levels of these genes were analysed in wild‐type tobacco plants and in the transgenic IAA‐overproducing line C, and related to the endogenous IAA level. In addition, effects of naphtyl‐1‐acetic acid (NAA) treatment on the expression of these genes were determined in both genotypes. Two separate situations were identified.Nt‐aux8andNt‐aux16steady‐state mRNA levels were positively correlated with the IAA content in wild‐type and line C plants. Addition of NAA induced these two genes strongly in wild‐type plants, but only slightly in line C plants. On the other hand, mRNA levels of theparAandparBgenes varied more with the organ analysed and its age than with the IAA level, and were induced by NAA treatment to a similar extent in the two genotypes. The results suggest that expression of the twoNt‐auxgenes is closely related to the endogenous auxin level, whereas expression of theparAandparBgenes to a greater extent is influen

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06671.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Chilling temperatures increase the amounts of potentially lethal toxic oxygen compounds present within plants. These toxic oxygen compounds can be scavenged by antioxidant compounds such as ascorbate and β‐carotene. Three developmental stages (first, third and fifth leaf) of four inbred lines of maize (Zea maysL.) exhibiting differential sensitivity to chilling were examined in order to determine if the chilling‐sensitive line had lower concentrations of antioxidant compounds than did the tolerant lines. Plants were exposed to one of three treatments: (1) control (25°C constant), (2) control treatment plus a short‐term chilling exposure of 11°C one day prior to harvesting, and (3) long‐term (11°C constant) chilling exposure. Total ascorbate, total glutathione, β‐carotene, α‐tocopherol and chlorophyll contents were quantified, and ratios of dehydroascorbate/ascorbate and reduced/oxidized glutathione were determined. Lower concentrations of β‐carotene were found in the chilling‐sensitive relative to those in the chilling‐tolerant lines for the first‐leaf stage under both short‐ and long‐term chilling treatments. Concentrations of total ascorbate and glutathione and β‐carotene in the chilling‐sensitive line increased as the chilling treatment progressed and as the plants developed until they ultimately became either significantly higher or no different relative to the tolerant lines. Results suggest that this sensitive line became less sensitive to chilling‐indu

ISSN:0031-9317    

DOI:10.1034/j.1399-3054.1996.980402.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Elucidation of the role of endogenous cytokinins in cambial activity and wood formation requires knowledge of their identity and concentrations in the cambial region. Here, we have used capillary liquid chromatography/frit‐FAB mass spectrometry to identify endogenous cytokinins in the vascular cambial region of maturePinus sylvestris(L.) trees. Full‐scan mass spectra were obtained for isopentenyladenine, isopentenyladenosine, zeatin riboside, dihydrozeatin and dihydrozeatin riboside. Of these, isopentenyladenine, dihydrozeatin and dihydrozeatin riboside are demonstrated by rigorous physico chemical methods for the first time in a conifer. In addition, an adenine glycoside was found for the first time in a plant. The identified cytokinins were quantified in active and dormant cambial region tissues by isotope dilution techniques using the appropriate deuterated isotope for each cytokinin species. The concentration of the detected cytokinins ranged between 1.3 and 5.5 pmol g‐1fresh weight, and did not vary greatly between dormant tissues, and in tissues actively dividing and differentiating. This observation indicates that cessation and reactivation of cell division activity in the vascular cambium is controlled by factors other than cytokinin availab

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06673.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

InLilium, a transformation system has not yet been developed. For efficient selection of cells expressing transferred genes following particle bombardment, the effects of 5’upstream regions on the transient expression of the β‐glucuronidase gene (gusA) were estimated in bulbscales and immature embryos of lily. When four plasmids having thegusAgene under the control of the cauliflower mosaic virus (CaMV) 35S, maize alcohol dehydrogenase gene and rice actin gene (Actl) promoters, and the castor bean catalase introm were introduced by particle bombardment, the patterns of transient expression in the bulbscales showed differences among threeLiliumspecies,L. x formolongi, L. dauricumandL. japonicum. In immature embryos ofL x formolongi, transient expression was significantly influenced by age of embryos after self‐pollination, duration of culture before bombardment, and culture conditions. Moreover, the transientgusAexpression driven by six different 5’upstream regions, including the maize ubiquitin gene promoter and a modified CaMV 35S promoter were compared in both bulbscales and immature embryos. Use of theActland modified CaMV 35S promoters resulted in the greatest number of cells that transiently expressedgusAin both types of tissue ofL. x formolongi. These two promoters are efficient for use in lily transf

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06674.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

We have developed and optimized a consistent polymerase chain reaction (PCR)‐based strategy to quickly obtain specific sequence information on novel plant glutamine synthetase (GS, EC 6.3.1.2) cDNAs. Two sets of degenerate primer pairs were designed to discriminate regions conserved in either any kind of GS messenger or exclusively in those for the chloroplastic GS. Novel GS cDNA sequences were successfully amplified from total RNA obtained from 14 different monocotyledonous and dicotyledonous plants. The procedure, coupled with a further restriction analysis, allowed us to uncover the presence of GS cDNA polymorphism, which most likely stems from the different GS gene family members within a single species. Contrary to previously reported strategies in other systems, GS cDNA oligonucleotide primers were designed keeping the degeneracy level to a minimum, together with a high melting temperature. This approach proved to be particularly effective, generating high yields of the expected products without requiring extra nested amplification steps or time‐consuming optimization steps for each species GS cDNA amplification. Different clones containing sequence information from either the coding or the 3′‐untranslated regions were further sequenced and characterized, confirming the high sequence identity and size uniformity the of GS cDNAs across higher plant species. Therefore, this approach is proposed as a stand‐alone procedure to quickly determine the sequence of unknown GS cDNAs, as well as to speed up and complement classical molecular cloning meth

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06675.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The aim of the study was to clarify the pigment content and light‐induced pigment formation in the grass mesocotyl (oats,Avena sativaL. cv. Seger I, and corn,Zea maysL. cv. Seneca). This organ, localized between root and coleoptile, only develops in darkness. To date, there are no data on its pigment content in the literature. The data found indicate a close relationship with conditions in roots, particularly with respect to the importance of yellow pigments as bleaching‐preventing agents and response to red and blue light. The mesocotyl contained small amounts of both Pchl628–632and Pchl636–642with a dominance of the former. Occasionally minute amounts of Pchl650–652were present, particularly in corn. The highest pigment concentration was found in the zone around the primordia of the pair of roots, which after several days in darkness protruded from the upper part of the mesocotyl close to the attachment to the coleoptile. Carotenoids were not detectable with absorption spectrophotometry. All pigments present in darkness were rapidly bleached in daylight and in strong red and blue light, and no more were synthesized under continuous irradiation. In continuous weak red and blue light small amounts of chlorophyll were formed at the same time as the protochlorophylls disappeared. Red light seemed to be somewhat more effective than blue, at least in corn. This chlorophyll biosynthesis stopped at very low values. The mesocotyls never became visibly green. Normal chloroplasts with grana did not develop. Mesocotyls, which had been irradiated for a short time, with no additional pigment formed, synthesized small amounts of Pchl when placed in darkness. ALA treatment of dark‐grown mesocotyls yielded Pchl628–632to a higher degree than di

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06676.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The aim of this study was to examine how the pools of non‐structural carbohydrates in soybean nodules are affected under water stress conditions depending on the nature of the symbiont strains with particular emphasis on the plant‐borne carbohydrates sucrose and pinitol, and on trehalose, a compatible solute synthesized by the bacteroids. Soybean (Glycine max[L.] Merr. cv. Maple Arrow) plants were inoculated with the nitrogen‐fixing strainsBradyrhizobium japonicum61‐A‐101 or USDA 110spc4and cultivated axenically under conditions in which nodules formed in an upper soil compartment while roots for water supply grew into a compartment filled with nutrient solution. When the nodules were well established (1 month post inoculation), 10% (w/v) PEG 6000 was added to the nutrient solution. This led to a slowly progressing, moderate water stress, as determined by measuring the decrease of transpiration, and to a decrease in nitrogen fixation. The pool sizes of the major non‐structural nodule carbohydrates changed during progression of water stress. Sucrose, the major soluble carbohydrate in nodules of unstressed plants (2 and 4%, respectively of nodule dry weight depending on symbiont strain), strongly increased in nodules of stressed plants, reaching nearly 10% of dry weight. The activities of two major sucrose‐consuming enzymes, sucrose synthase and alkaline invertase, decreased markedly in nodules of stressed plants. Starch decreased only transiently upon water stress. Pinitol, a cyclitol serving as compatible solute in many plants, increased more than 4 times, reaching about 1% of nodule dry weight during the stress. Trehalose, the major soluble carbohydrate synthesized by the bacteroids, increased in nodules colonized by USDA 110spc4from about 0.2 to 0.8% of nodule dry weight, while in nodules colonized by 61‐A‐101 it amounted to more than 1.5% of dry weight both with a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06677.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The levels of ascorbic acid (AA) and dehydroascorbic acid (DHA) in the apoplast of epicotyl segments fromVigna angularisL. cv. Erimoshouzu decreased to nearly zero and about 35%, respectively, of their initial levels, 3 h after the preparation of the epicotyl segments. The decreased level was kept nearly constant between 3 and 7 h. Fusicoccin (FC) and indole‐3‐acetic acid (IAA) slightly amplified the initial decrease in the level of AA, but suppressed the initial decrease in the level of DHA while enhancing elongation growth. During incubation for 3 and 7 h, FC then increased the levels of both AA and DHA, whereas IAA did so only with DHA. By the addition of FC 4 h after the start of incubation, the levels of both AA and DHA were also increased. The uncoupler carbonylcyanidem‐chlorophenyl hydrazone increased the levels of both AA and DHA in the apoplast inhibiting elongation growth. These results suggest that the electrochemical proton gradient across the plasma membrane is one of the factors that control the apoplastic levels of AA an

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06678.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Inoculation of the stems of threeCapsicum annuumL. cultivars showing different degrees of sensitivity to the fungal pathogenPhytophthora capsici, resulted in a hypersensitive reaction being expressed along the stems. One of the peppers (cv. Smith‐5) showed resistance by total inhibition of fungal growth. Capsidiol, a phytoalexin, which accumulates in the area of necrosis appears to be involved in this resistance. Capsidiol accumulation was analyzed by gas chromatography and was correlated with the restricted growth ofP. capsici, in vivo and in vitro, confirming the former's fungistatic and fungitoxic properties. The capacity to inhibit pathogenic growth was evident only when capsidiol production exceeded 1 204 μg ml‐1, a level reached in the resistant variety after 6 days of incubation. Experiments on induced resistance showed that a second inoculation of the stems of the three cultivars also resulted in necrosis and in an accumulation of capsidiol, although to a lesser extent than in the first inoculation. The greater accumulation of capsidiol in the stems of cv. Smith‐5 is in accordance with the resistance shown by this cultivar toP. capsici, and confirms the implication of capsidiol in the disease resistance of this cultivar to fungal pathogens. Capsidiol has a fungistatic character at a mean concentration of 3.75 mM, and is fungitoxic at levels above 5 mM. This level must be exceeded and all the growing hyphae must be affected for capsidiol to qualify from being fungistatic to being fung

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06679.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Potato (Solanum tuberosumL. cv. Russet Burbank) tubers undergo a period of endodormancy that is characterized by cell division arrest. At the time of harvest, the tubers used in this study were completely endodormant (i.e. 0% sprouting). After 120 days of storage at 3°C, tubers transferred to 20°C had begun to exit endodormancy and exhibited ca 50% sprouting. After 223 days of 3°C storage, tubers transferred to 20°C were completely nondormant and exhibited 100% sprouting. Based on flow cytometry, about 70% of nuclei isolated from endodormant meristems are arrested in the G1/G0phase of the cell cycle. Storage of tubers at 3°C did not alter the cell cycle position nor did transfer of tubers from 3 to 20°C for 7 days prior to analysis unless tubers had been stored for at least 223 days. After 223 days of cold (3°C) storage, tubers transferred to 20°C for 7 days showed sprout growth in excess of 5 mm and an increase in the percentage of nuclei in the G2phase of the cell cycle. Uptake and incorporation of3H‐thymidine into DNA was low in all tubers up until 120 days postharvest. After that time, only tubers incubated at 20°C for 7 days prior to analysis exhibited an increase in3H‐thymidine incorporation. This increase coincided with visible sprout growth, demonstrating that cell cycle shifts in tuber meristems relate directly to sprout growth and not the breakage of the endodormancy per se. Using degenerate primers, a portion of a p34cdc2homolog was amplified from RNA isolated from logphase potato suspension culture cells by polymerase chain reaction. Northern analysis with this probe demonstrated that mRNA levels for two p34cdc2homologs were present throughout the endodormant period. Immunoblot analysis demonstrated that levels of at least four proteins containing a PSTAIRE epitope (i.e. cdc2‐like) were present at reduced levels in endodormant meristems and increased in reactivated tuber meristems that showed a shift in cell cycle kinetics based on flow cytometry and increased3H‐thymidine incorporation. These results indicate that the temporal shift in competence for cell division in potato meristems induced by dormancy is not accompanied by alterations in the level of mRNA for p34cdc2homologues but is correlated with a change in the level of PSTAIRE‐containing proteins. This suggests that during endodormancy cell division in potato tuber meristems is regulated indirectly by posttranscriptional regulation of genes controll

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1996.tb06680.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY