摘要:

Dramatic differences in the height of lima beans (Phaseolus lunatusL.) treated with two differentRhizobiumstrains were studied. Lima beans were grown in Perlite in the greenhouse or in a minus-N culture solution in the growth chamber. The plants were inoculated with eitherRhizobiumsp. (lima bean) strain 127E15, which contains the constitutive nitrate reductase activity, or strain 127E14, which lacks that activity. For up to 3 weeks, no growth differences were observed in the plants inoculated with either strain. Five weeks after inoculation, however, those plants inoculated with strain 127E14 were significantly taller and had a larger number of leaves than those inoculated with strain 127E15. The difference in plant height was the result of increased internode elongation caused by inoculation withRhizobiumsp. 127E14. This response was observed with all lima bean cultivars tested, including Henderson, Fordhook, Allgreen, and Early Thorogreen. The growth difference occurred in plants cultured in the greenhouse or in the growth chamber.No differences were observed in fresh weights of nodules, roots, axes, leaves, or flowers. The number of nodules, pods, or flowers also did not differ. Acetylene reduction rates and total N content were equal in plants inoculated with strains 127E14 or 127E15.Inasmuch as only internode length and leaf number differed betweenRhizobiumtreatments, the response appeared to be hormone-mediated. Application of gibberellic acid to the apex of plants inoculated with strain 127E15 caused an increase in plant height similar to that observed in untreated plants inoculated with strain 127E14. Conversely, the height of plants infected with strain 127E14 was decreased by application of gibberellin synthesis inhibitors to the root system. These data suggest that the increased growth caused by inoculation with strain 127E14 could be the result of increased gibberellin synthesis in lima bean nodules infected with that strain. Whether this response was related to the absence of nitrate reductase activity in strain 127E14 is unknown.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

A procedure is described for isolating photosynthetically active rhodoplasts (“red algal chloroplasts”) from the marine algaGriffithsia monilis.The rhodoplasts exhibited rates of CO2fixation and CO2-dependent O2evolution in the order of 200 micromoles per milligram chlorophyllaper hour when illuminated with red or green light and were approximately 80% intact. The response of the rate of photosynthesis to the inorganic phosphate and pyrophosphate concentrations in the medium was qualitatively similar to that previously reported for spinach chloroplasts. Osmotically shocked rhodoplasts evolved O2from ferricyanide in red, but not in green, light and were completely uncoupled. Rhodoplast envelope rupture appeared to be accompanied by phycobilisome loss from the thylako

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

Microsomal membranes from potato tubers were treated with a phospholipase C extracted fromBacillus cereus.A positive correlation could be observed between the hydrolysis of membranous phospholipids and the decrease of the NADH-cytochromecreductase activity. Addition of total lipid or phospholipid micelles to phospholipase C-treated microsomes partially restored the NADH-cytochromecreductase activity, thus proving the lipid-dependence of this enzyme.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

A new procedure is reported for high-yield isolation of guard cell protoplasts fromVicia fabaL. Delayed light emission and P700content plus absorption and fluorescence emission spectra of these protoplast extracts are reported. It is concluded that both photosystems are present. The presence of photosystem II and the absence of the reductive-step enzyme of the Calvin-Benson Cycle (Outlaw WH Jr, J Manchester, CH DiCamelli, DD Randall, B Rapp, GM Veith 1979 Proc Natl Acad Sci USA 76: 6371-6375) in a cell has no precedent in the literature. It is speculated that noncyclic photosynthetic electron flow is an environmental sensor which causes stomata to remain open in light.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

The presence of chloroplasts in guard cells from leaf epidermis, coleoptile, flowers, and albino portions of variegated leaves was established by incident fluorescence microscopy, thus confirming the notion that guard cell chloroplasts are remarkably conserved. Room temperature emission spectra from a few chloroplasts in a single guard cell ofVicia fabashowed one major peak at around 683 nanometers. Low-temperature (77 K) emission spectra from peels of albino portions ofChlorophytum comosumleaves and from mesophyll chloroplasts of green parts of the same leaves showed major peaks at around 687 and 733 nanometers, peaks usually attributed to photosystem II and photosystem I pigment systems, respectively. Spectra of peels ofV. fabaleaves showed similar peaks. However, fluorescence microscopy revealed that theViciapeels, as well as those fromAllium cepaandTulipasp., were contaminated with non-guard cell chloroplasts which were practically undetectable under bright field illumination. These observations pose restrictions on the use of epidermal peels as a source of isolated guard cell chloroplasts. Studies on the 3-(3,4-dichlorophenyl)-1,1-dimethylurea-sensitive variable fluorescence kinetics of uncontaminated epidermal peels ofC. comosumindicated that guard cell chloroplasts operate a normal, photosystem II-dependent, linear electron transport. The above properties in combination with their reported inability to fix CO2photosynthetically may render the guard cell chloroplasts optimally suited to supply the reducing and high-energy phosphate equivalents needed to sustain active ion transport during stomatal opening in daylight.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

Glyoxysome ghosts were isolated from germinating castor bean endosperms using established methods. Electron microscopic examination showed that some matrix material was retained within the glyoxysomal membrane. Two cytochrome reductases and phosphorylcholine glyceride transferase co-sedimented with the alkaline lipase, a known component of the glyoxysome membrane, in sucrose gradient centrifugation of osmotically shocked glyoxysomes. The activities of these enzymes in the glyoxysome membranes were compared to those in the endoplasmic reticulum relative to phospholipid content. On this basis, the phosphorylcholine glyceride transferase was 10-fold more active in the endoplasmic reticulum, whereas the lipase was 50-fold more active in the glyoxysome membrane. The cytochrome reductases were only 2-fold more active in the endoplasmic reticulum, indicating that they are components of the two membranes. Difference spectroscopy of the glyoxysome membrane suspension revealed the presence of ab5-type cytochrome similar to that found in the endoplasmic reticulum. Since the glyoxysome membrane is apparently derived from the endoplasmic reticulum, components of the endoplasmic reticulum such as these are likely to be incorporated into the glyoxysome membrane during biogenesis.Enzyme activities involving the cofactors NADH or CoA were measurable in broken, but not in intact, glyoxysomes. Thus, it appears that cofactors for enzymes within the organelle cannot pass through the membrane.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

To investigate the abscisic acid (ABA) production of tomato (Mill.) plants in response to diurnal stressful temperatures, five-week old seedlings were exposed to day/night temperatures of 10/5, 15/10, 25/15, 35/25, or 45/35 C. The daylength was 16 hours with a light intensity of approximately 400 microeinsteins per meter per second. Plant tops were sampled at 12, 24, 48, and 72 hours. Free, alkaline-hydrolyzable (conjugated), and total ABA quantities were measured using standard gas chromatographic techniques. All temperature regimes significantly increased both free and conjugated ABA levels over concentrations in control plants (25/15 C). The highest ABA levels were observed in plants exposed to the coolest temperature of 10/5 C. Since normal water potentials were obtained in plants of all treatments, the observed ABA response was not due to temperature-induced water stress. Therefore, temperature stress, like several other environmental stresses, induces the plant to produce high levels of ABA. Because of the similar involvement of ABA in temperature-induced and other environmental stresses, ABA may be a common mediator for all plant stresses.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

Empirically based models depicting exchanges of C, N, and H2O in phloem and xylem among organs of nodulated white lupin (Lupinus albuscv Ultra) were constructed for the interval 51 to 58 days after sowing. Information was incorporated on the economy of C, N, and H2O in plant parts, the solute composition of transport fluids collected at selected sites on the plant, and the photosynthetic inputs, transpirational losses, and translocatory activities of different age groups of leaflets and stem + petiole segments of the shoot. Partitioning of C and N showed preferential transfer of N to the shoot apex, which imported 13 milligrams C per milligram N, compared with 54 milligrams C per milligram N for the nodulated root. Leaves translocated assimilates at a C:N weight ratio of 43 to 59, and older leaves serving the roots produced the translocate most rich in N relative to C. The shoot apex was enriched with N, additional to its intake from leaves, by direct uptake of xylem fluid (C:N ratio, 2.4) and receipt of nitrogenous solutes transferred from xylem to upward-moving phloem streams in upper regions of the stem. The models for flow of N and H2O indicated that xylem streams passing to leaves were substantially less rich in N than the adjacent stream moving through the body of the stem and that a progressive increase in concentration of N occurred within stem xylem elements from base to top of the shoot. This apparently resulted from an abstraction of N from xylem of departing leaf traces, possibly by xylem transfer cells, and a subsequent feedback of this N to xylem streams passing on up the shoot. Upper leaves and shoot apex, therefore, acquired more N from xylem per unit of H2O transpired than lower parts of the shoot.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

Changes in total N and in free amino compounds were followed during growth of nodulated white lupin. Leaflets contained the greatest fraction of plant N but had lower proportions (1 to 4%) of their N in soluble amino form than stem + petioles (10 to 27%) and reproductive parts (15 to 33%). Mobilization of free amino compounds from plant parts to fruits contributed at most only 7% of the total N intake of fruits, compared with 50% in mobilization of other forms of N and 43% from fixation during fruiting. Asparagine was usually the most abundant free amino compound in plant parts, followed by glutamine and alanine. Valine, glycine, isoleucine, aspartic acid andγ-aminobutyric acid comprised the bulk of the remaining soluble amino N. Composition of tissue pools of amino-N closely resembled that of xylem and phloem exudates. Data on N flow and utilization were combined with information on composition of transport fluids to quantify syntheses, exchanges, and consumptions of asparagine, glutamine, aspartic acid, and valine by organs of the 51- to 58-day plant. These amino compounds carried 56, 29, 5, and 2%, respectively, of the N exported from nodules and contributed in roughly commensurate proportions to transport exchanges and N increments of plant parts. There were, however, more than expected involvements of glutamine and valine in mobilization of N from lower leaves, of asparagine in xylem to phloem transfer, and of aspartic acid in cycling of N through the root, and there was a less than expected participation of aspartic acid in xylem to phloem transfer and in phloem translocation to the shoot apex. The significance of these differences is discussed

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB

摘要:

Root and stem segments from soybean (Merrill cv. `Bragg') showed an enhanced chemiluminescence upon mechanical injury. Roots emitted more light than did stems. Light emission was diminished by CN−and N3−but was not affected by rotenone and antimycin A. Catalase quenched chemiluminescence in wounded root segments as did ascorbic acid and hydroquinone. Superoxide dismutase addition resulted in a small diminution in light emission, but mannitol, an OH·scavenger, was without effect. The addition of H2O2to wounded root segments markedly elevated chemiluminescence in the presence of air as well as under N2. It is concluded that peroxidases, found abundantly in roots, predominantly contribute to light emission in wounded plant ti

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1981

数据来源: ASPB