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PubMed1967

Interactive Effects of CO(2) and O(2) in Soil on Root and Top Growth of Barley and Peas.

Barley and pea plants were grown under several regimens of different compositions of soil atmosphere, the O(2) concentration varying from 0 to 21% and the CO(2) concentration from 0 to 8%. In absence of CO(2), the effect of O(2) on root length in barley was characterized by equal root lengths within the range of 21 to 7% O(2) and a steep decline between 7 and 0%. In peas, while showing the same general response, the decline occurred between 14 and 7% O(2). Root numbers of the seminal roots of barley decreased already with reduction in O(2) concentration from 21 to 14%. Dry matter production was affected somewhat differently by O(2) and CO(2) concentration. Dry matter production in barley was reduced at 14% O(2) while root length decreased between 7 and 0%. In peas, dry matter production was favored by low CO(2) concentrations except where there was no oxygen. At 21% O(2), increasing CO(2) concentrations did not seem to affect root length up to concentrations of 2% CO(2). At 8% CO(2), root length was decreased. The inter-active effects of CO(2) and O(2) are characterized by a reduced susceptibility to CO(2) at O(2) values below 7%, and a very deleterious effect of 8% CO(2) at 7% O(2).

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PubMed1970

Grafting and gibberellin effects on the growth of tall and dwarf peas.

Tall peas var. Alaska and dwarf peas var. Progress No. 9 were grafted onto their own roots or reciprocally grafted to determine the rootstock effect on the growth of the stem. In all cases the grafted stems grew the same as their ungrafted controls regardless of which rootstock they were grown on. When similarly grafted plants were supplied with gibberellic acid, good graft unions did not inhibit its translocation. This evidence supports the thesis that the mechanism controlling stem growth in peas is located in the stem and that the roots have no direct control over this mechanism.

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PubMed1970

Changes in Nucleic Acids in Phytochrome-dependent Elongation of the Alaska Pea Epicotyl.

Red light, which produces the physiologically active form of phytochrome (Pfr), inhibited epicotyl elongation in intact dark-grown Alaska pea seedlings. This red light response was detectable 3 hours after the light treatment and became pronounced after 5 hours. The growth inhibition was completely reversed by far red light applied immediately after the red or by pretreatment of the seedlings with the plant hormone gibberellin A(3).Comparison of the total (32)P-labeled nucleic acids from control and red light-treated Alaska pea epicotyls on methylated albumin-kieselguhr columns revealed a marked alteration of the pattern of nucleic acid synthesis in this plant material with little or no effect on total isotope incorporation into nucleic acids. A single 5-minute red light perturbation caused a 2-fold stimulation of (32)P incorporation into the tRNA fraction while, simultaneously, (32)P incorporation into tenaciously bound RNA was reduced to 50% of control levels. Red light treatment had no effect on (32)P incorporation into the DNA-RNA, rRNA, or mRNA fractions. Far red light reversed the effect of red light on tRNA synthesis but did not restore tenaciously bound RNA levels to the control value. Gibberellin A(3) treatment did not cause reversal of any of the red light effects on RNA synthesis.These light-induced changes in nucleic acids were measurable before any changes in the physiological response (epicotyl elongation) could be detected. These results are consistent with a phytochrome-mediated differential gene activation mechanism in the Alaska pea epicotyl elongation system.

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PubMed1971

Mass isolation of pea nuclei.

Improvements in conventional filtration and centrifugation procedures made it possible to increase the yield of intact cytoplasm-free pea (Pisum sativum) nuclei from the usual 3 to 10% to 32% (6 x 10(8) nuclei per 7 grams fresh weight of pea apices) and to complete the isolation in 80 to 90 minutes. The isolated nuclei appeared to retain their structural integrity as revealed in electron photomicrographs, and remained intact for at least 5 hours at 20 Celsius.The DNA:RNA: protein ratio of isolated pea nuclei was found to be 3.1:1:9.9. Their RNA polymerase activity, monitored by incorporation of (14)C into RNA from (14)C-UTP, was linear for about 10 minutes, and then gradually declined over the next 15 to 20 minutes.

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PubMed1971

Regulation by auxin of carbohydrate metabolism involved in cell wall synthesis by pea stem tissue.

Promotion of cell wall synthesis (from glucose) in pea (Pisum sativum) stem segments by indoleacetic acid (IAA) develops over a period of 1 to 2 hours and is comprised of a promotion of glucose uptake plus a promotion of the utilization of absorbed glucose. The effect of IAA resembles, in these and other respects, its effect on cell wall synthesis in oat coleoptile segments, but the pea system differs in not being inhibited by galactose or mannose, in involving considerably more isotope dilution by endogenous substrates, and in certain other respects.EFFECTOR INFLUENCES UPON AND TOTAL ACTIVITIES OF THE FOLLOWING ENZYMES OBTAINED FROM ETIOLATED PEA STEM SEGMENTS PRETREATED WITH OR WITHOUT IAA WERE EXAMINED: phosphoglucomutase, uridine diphosphate glucose (UDP-glucose) pyrophosphorylase, nucleoside diphosphokinase, UDP-glucose dehydrogenase, inorganic pyrophosphatase, hexokinase (particulate and soluble), and UDP-glucose-beta-1,4-glucan-glucosyl transferase (beta-glucan synthetase). The first three enzymes mentioned exhibit high activity relative to the flux in vivo, do not appear to show physiologically significant effector responses, and are concluded not to be control points. UDP-glucose dehydrogenase activity is regulated by UDP-xylose. Hexokinase is a potential control point but does not exhibit regulatory effects related to the IAA response. beta-Glucan synthetase is the only one of these enzymes with activity which is increased by treatment of tissue with IAA, and this may be responsible for the effect of IAA on wall synthesis.Assays of metabolite pools support the conclusion that stimulation of polysaccharide synthesis by IAA is due partly to changes in hexokinase reaction rate resulting from an increase in metabolic glucose pool size caused by increased glucose uptake, and partly to increased activity at the polysaccharide synthetase level.

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PubMed1973

Control of the formation of amylases and proteases in the cotyledons of germinating peas.

Protease activity increased in attached cotyledons of germinated peas (Pisum sativum L. cv. Alaska) as the stored proteins declined but did not increase in excised cotyledons incubated for the same length of time. Cotyledons of seeds germinated in the presence of a casein hydrolysate solution developed less protease activity than did those germinated on water. These results suggest that accumulation of amino acids regulates the protease level in the cotyledons of germinating peas.In contrast to protease, alpha- and beta-amylase increased during incubation of excised pea cotyledons. Their increase was inhibited by abscisic acid. Abscisic acid did not inhibit (14)C-leucine incorporation into protein or reduce the respiratory rate in the cotyledons; hence, its effect on amylase formation was not the result of a general inhibition of metabolism. An ether-soluble acid fraction, which would contain any abscisic acid present in the material, inhibited amylase formation more when it was obtained from imbibed seeds than when it was obtained from cotyledons of seeds germinated for 10 days. These and other results suggest that amylase formation in germinating peas is regulated by abscisic acid.

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PubMed1973

Structural Development during Germination of Different Populations of Mitochondria from Pea Cotyledons.

The crude mitochondrial fraction from pea cotyledons can, from days 1 to 7 of germination, be separated into three fractions by sucrose density gradient centrifugation. When seeds were grown in water (control) or cycloheximide (120 micrograms per milliliter of medium) for 4 days, the originally different populations of mitochondria acquired a uniform density and separated together in band 1 (density, 1.205 grams per milliliter). The oxidative and phosphorylative activities of mitochondria obtained from 4-day-old control and 4-day-old cycloheximide-treated pea seeds were the same. However, mitochondria from pea seeds that were grown in d-threo-chloramphenicol (1.5 milligrams per milliliter of medium) or erythromycin (0.5 milligram per milliliter of medium) for 4 days separate into three bands (fully developed mitochondria in the top band [band 1] and partially developed mitochondria in the lower two bands [bands 2 and 3]). Separation patterns and oxidative and phosphorylative activities were the same for mitochondria separated from 4-day-old cotyledons treated with d-threo-chloramphenicol or erythromycin and from 1-day-old cotyledons grown in water. This indicated that these inhibitors prevented the partially developed mitochondria originally in bands 2 and 3 from developing further. In contrast, cycloheximide did not seem to interfere with the mitochondrial structural development. These results along with those obtained from the experiments on the effects of d-threo-chloramphenicol, erthromycin, and cycloheximide on (14)C-leucine incorporation into mitochondrial membrane proteins suggest that the increase in mitochondrial activity during germination may be a result of structural development (membrane synthesis) in pre-existing mitochondria.

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PubMed1974

Correlations of Growth Rate and De-etiolation with Rate of Ent-Kaurene Biosynthesis in Pea (Pisum sativum L.).

Biosynthesis of the gibberellin precursor ent-kaurene-(14)C from mevalonic acid-2-(14)C was assayed in cell-free extracts of shoot tips of etiolated and light-grown Alaska (normal) and Progress No. 9 (dwarf) peas (Pisum sativum L.). During ontogeny of light-grown Alaska peas, kaurene-synthesizing activity increased from an undectectable level in 3-day-old epicotyls to a maximum in shoot tips of 9-day-old plants and remained relatively constant thereafter until postanthesis. The capacity for kaurene synthesis in extracts from shoot tips of 10-day-old etiolated Alaska seedlings increased approximately exponentially during the first 12 hr of de-etiolation in continuous high intensity white light and remained relatively constant during the succeeding 24 hr of irradiation. Extracts from light-grown Alaska (normal) shoot tips possessed greater capacity for kaurene synthesis than did extracts from light-grown Progress No. 9 (dwarf) shoot tips. Extracts from shoot tips of either light-grown cultivar displayed greater kaurene-synthesizing capacity than was observed in extracts from their dark-grown counterparts. It is concluded that gibberellin biosynthesis in pea shoot tips is subject to partial regulation by factors controlling the rate of biosynthesis of kaurene.

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PubMed1974

Mode of Pisatin Induction: Increased Template Activity and Dye-binding Capacity of Chromatin Isolated from Polypeptide-treated Pea Pods.

Increases in phenylalanine ammonia lyase activity and pisatin synthesis were induced in excised pea pods (a) by basic polypeptides such as protamine, histone, lysozyme, cytochrome c, and ribonuclease; (b) by the polyamines spermine, spermidine, cadaverine, and putrescine, and (c) by the synthetic oligopeptides poly-l-lysine, poly-dl-ornithine, and poly-l-arginine.Poly-l-lysine (1 milligram per milliliter, molecular weight 7,200) was utilized as a model inducer of pisatin and phenylalanine ammonia lyase. The poly-l-lysine-induced responses could be inhibited by adding the RNA synthesis inhibitors cordycepin or alpha-amanitin to the pods prior to or at the time of inducer application. Cordycepin added 1.5 hours after inducer no longer completely inhibited induction. The application of poly-l-lysine was shown to characteristically change the rate of RNA synthesis within 30 minutes. Ultrastructural changes in pea nuclei were detected within 3 hours, and gross changes in nuclear morphology were apparent at 14 hours after inducer application. The physical appearance of uranyl acetate-stained chromatin isolated from poly-l-lysine 2 hours after inducer application differed from that of water-treated tissues. The template properties of chromatin extracted from pods 3 hours after inducer application were consistently superior to control chromatin when assayed with Escherichia coli RNA polymerase (without sigma factor). Chromatin from poly-l-lysine-induced tissue also bound 49% more actinomycin D-(3)H.The DNA-complexing properties of inducer compounds and the induced changes in the template and dye-binding properties of pea chromatin formed the basis for a proposed mode of action for phytoalexin induction.

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PubMed1974

Effects of ethylene and gibberellic Acid on cellular growth and development in apical and subapical regions of etiolated pea seedling.

Subhook swelling of 4-day-old etiolated pea seedlings (var. Alaska), caused by 0.5 microliter per liter ethylene, was prevented by preincubation and continued growth in 0.1 mm gibberellic acid (GA). The subhook region exhibited normal elongation and cell size and volume. However, inhibition of elongation and cessation of cell division caused by 0.5 microliter per liter ethylene in the apical hook region of the etiolated pea stem were not overcome by GA. Most of the arrested cells were in G(2). These data suggest a possible interaction of GA and ethylene in cell enlargement in the subhook region of the etiolated pea seedlings. They also suggest a different mode of action by ethylene in the apical hook region where the ethylene effect was not counteracted by GA.

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PubMed1975

Effects of ethylene, kinetin, and calcium on growth and wall composition of pea epicotyls.

Ethylene supplied with indoleacetic acid at 0.1 and 1 mum inhibited elongation and enhanced swelling in epicotyls of decapitated and derooted pea seedlings (Pisum sativum L., var. Alaska). These growth responses were correlated with the development of cell walls rich in weak acid-extractable materials and pectic uronic acids. Ethylene had no effect on the formation of hemicellulose, or hemicellulosic uronic acid. Ethylene stimulated the formation of residual materials at 0.1 mum indoleacetic acid but had little effect at 1 mum. With indoleacetic acid at 10 mum, ethylene modified neither the growth or wall composition appreciably. Growth and wall composition in intact seedlings were modified in similar fashion by ethylene. In intact seedlings ethylene promoted the development of walls high in weak acid-extractable materials and pectic uronic acid. These effects were less impressive in the first 24 hours than in the second 24 hours when the control plants suffered a net loss of these constituents. Ethylene considerably inhibited the formation of hemicellulose and residual wall materials in the apical sections but promoted it in the basal sections of the intact seedlings.Measurements of ethylene production by decapitated and derooted pea seedlings suggest that Ca(2+) and kinetin do not promote swelling through an effect on the formation of ethylene.We propose that cells of ethylene-treated pea epicotyls lack polarity because their walls are abnormally rich in pectic substances.

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PubMed1975

Effects of gibberellic Acid, calcium, kinetic, and ethylene on growth and cell wall composition of pea epicotyls.

The influence of gibberellic acid (GA), calcium, kinetin, and ethylene on growth and cell-wall composition of decapitated pea epicotyls (Pisum sativum L. var. Alaska) was investigated. Calcium, kinetin, and ethylene each caused an inhibition of GA-induced elongation of pea stems. Gibberellic acid did not reverse the induction of swelling by Ca(2+), kinetin, or ethylene. Both Ca(2+) and ethylene significantly inhibited the stimulatory effects of GA on the formation of residual wall material. Although GA promoted the development of walls relatively low in pectic substances and pectic uronic acid, Ca(2+), kinetin, and ethylene favored the formation of walls rich in these constituents. Calcium, kinetin, and GA, alone or in combination, had no effect on the production of ethylene by pea epicotyls.

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PubMed1977

Photosynthesis by isolated pea chloroplasts: some effects of adenylates and inorganic pyrophosphate.

When added singly to chloroplasts isolated from young pea (Pisum sativum) leaves, both inorganic pyrophosphate (PPi) and small quantities (0.2 mm) of ADP inhibit photosynthesis, but when added together they cause a marked stimulation. ATP (at 0.2 mm) is less inhibitory (or not inhibitory) when added alone, but like ADP, stimulates when added in the presence of PPi. This behavior is in marked contrast to that of spinach (Spinacia oleracea) chloroplasts which are normally stimulated rather than inhibited by PPi and which are largely unresponsive to exogenous adenylates. The inhibitory behavior of PPi with pea chloroplasts was observed under conditions where external hydrolysis to Pi is negligible. It is proposed that the exchange of organic and PPi across the chloroplast envelope may be more rapid in chloroplasts from young pea leaves than in chloroplasts from spinach and that interaction between these two processes could account for the principal observations.

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PubMed1978

Effects of Protein Synthesis Inhibitors on ent-Kaurene Biosynthesis during Photomorphogenesis of Etiolated Pea Seedlings.

Excised shoot tips from 10-day-old etiolated pea (Pisum sativum L. cv. Alaska) seedlings were incubated in solutions of chloramphenicol, cycloheximide, and lincomycin at different concentrations during periods of 0, 4, 8, and 12 hours of irradiation with high intensity white light. Enzyme extracts were prepared from the whole shoot tips and compared with extracts from nontreated shoot tips for their capacity to synthesize ent-kaurene from mevalonate. In control samples, kaurene synthesis increased during the first 8 hours of irradiation and decreased after 12 hours. Chlorophyll content increased steadily up to 12 hours of irradiation. Chloramphenicol and cycloheximide reduced both kaurene synthesis and chlorophyll formation to a similar extent during all periods of irradiation, the reduction being greatest after 8 hours of irradiation. Lincomycin, a specific inhibitor of the formation of chloroplast ribosomes in detached pea shoot tips, did not significantly affect kaurene synthesis activity but strongly inhibited chlorophyll formation. It is tentatively concluded that the increase in kaurene synthesis activity during normal photomorphogenesis in pea seedlings is due to photoinduction of de novo synthesis of one or more proteins involved in the biosynthetic pathway from mevalonate to kaurene.

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PubMed1979

Indole-3-acetic Acid Oxidase from Peas: I. Occurrence and Distribution of Peroxidative and Nonperoxidative Forms.

Tissues of etiolated pea seedlings variety Alaska were examined for the presence of peroxidative and nonperoxidative forms of indoleacetic acid (IAA) oxidase. Enzymes were extracted in a sequence involving acetone powder preparation from pea tissues, buffer extraction of the powder, ammonium sulfate precipitation, dialysis, lyophilization, and acrylamide gel electrophoresis. Electrophoretically separable proteins were assayed for IAA oxidase activity with the Salkowski test, and peroxidase activity was based on the color reaction with benzidine and H(2)O(2). Each tissue examined contained several nonperoxidative IAA oxidases. No tissue contained more than three peroxidative IAA oxidases, whereas the plumule hooks (a tissue with a high IAA oxidase activity) contained no detectable peroxidases. The results indicate that nonperoxidative IAA oxidases might play a major role in the regulation of IAA content in pea seedlings.

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PubMed1979

Changes in Chloroplast DNA Levels during Development of Pea (Pisum sativum).

Determinations were made of the percentage of chloroplast DNA (ct DNA) in total cell DNA isolated from shoots of pea at different stages of development. Labeled pea ct DNA was reassociated with a high concentration of total DNA; the percentage of ct DNA was estimated by comparing the rate of reassociation of this reaction with that of a model reaction containing a known concentration of unlabeled ct DNA. The maximum change in ct DNA content was from 1.3% of total DNA in young shoots to 7.3% in fully greened shoots. Analyses were also performed on DNA from embryos, etiolated tissue, roots, and leaves. The first leaf set to develop in pea was excised over a growth period of 8 days during which leaf length increased from 4 to 12 millimeters. Young leaves contained about 8% ct DNA; in fully greened leaves the level of ct DNA approached 12%, equivalent to as many as 9,575 copies of ct DNA per cell. Root tissue contained only 0.4% ct DNA.

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PubMed1981

Precursor Forms of Pea Vicilin Subunits: MODIFICATION BY MICROSOMAL MEMBRANES DURING CELL-FREE TRANSLATION.

Polyribosomal RNA isolated from pea cotyledons at various developmental stages programmed the cell-free synthesis of polypeptides which were recognized by antibodies specific for pea storage proteins. There were quantitative and qualitative changes in the template activity during seed maturation. Most of the polysomal RNA was associated with the membrane fraction, and all of the template for storage protein occurred in this fraction. Using RNA from a stage of seed maturation at which the synthesis of the high-molecular weight vicilin polypeptides predominate, it was found that the major translation products, although antigenically recognizable as storage protein, did not coincide with the authentic vicillin polypeptides on denaturing polyacrylamide gels. The addition during translation of microsomal membranes from dog pancreas or pea cotyledons resulted in the appearance of new polypeptides which did coincide with some of the authentic vicilin polypeptides (in the apparent molecular weight regions of 75,000 and 50,000) and were antigenically recognizable as storage protein. Other translation products related to storage protein were not visibly altered in their electrophoretic mobility by the addition of membranes. Microsomal membranes treated with Triton X-100 were not effective in modifying the cell-free products. The modified vicilin polypeptides and at least two other translation products were protected from proteolytic degradation, suggesting that they were sequestered within microsomal vesicles. Thus, these storage protein components may be synthesized by a mechanism analogous to that described for membrane and secretory proteins (Blobel G, B Dobberstein 1975 J Cell Biol 67: 835-851).

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PubMed1981

Effect of salt on auxin-induced acidification and growth by pea internode sections.

The capacity of excised internode sections of pea to grow and secrete protons in response to indoleacetic acid (IAA) and Ca(2+) and K(+) treatments was examined. By incubating unpeeled and unabraded sections in rapidly flowing solutions, it was shown that acidification of the external medium in the presence or absence of IAA is dependent on the presence of Ca(2+) and K(+). Similar results were obtained when unpeeled and unabraded sections were incubated in dishes with shaking. When peeled or abraded sections were incubated with shaking in IAA, H(+) release was also dependent on the presence of Ca(2+) and K(+). The release of H(+) from sections incubated in Ca(2+) and K(+) is not caused by displacement of H(+) from binding sites in the cell wall. Rather, the release of protons from sections is temperature dependent, and it is concluded that this is a metabolically linked process. Although Ca(2+) and K(+) are essential for the release of H(+) from isolated stem sections of peas, these cations do not influence elongation. Despite the large increase in proton release induced by Ca(2+) and K(+) either in the presence or absence of auxin, growth in the presence of these ions was never greater than it was in their absence. Furthermore, cations do not affect the neutral sugar or uronic acid composition of the solution which can be centrifuged from isolated sections. As is the case for growth, an increase in the neutral sugar and uronide composition of the cell wall solution is dependent only on IAA. It is concluded that IAA-induced growth of pea stem sections is independent of the secretion of protons.

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