Plant Physiology

Halaban, Ruth

doi: 10.1104/pp.43.12.1883pmid: 16656985

Abstract A new instrument for the recording of leaf movement rhythm is described. Coleus blumei x C. frederici, a short day plant, exhibits a circadian rhythm of leaf movement. The period length of the free running rhythm is shortest in continuous darkness and is increased with an increase in the light intensity. The amplitude of the rhythm tends to damp in continuous bright light. 1 The material presented in this paper is a part of a dissertation submitted to the Department of Biology, Princeton University in partial fulfillment of the requirements for the degree of Doctor of Philosophy. 2 Supported in part by a NSF grant to Dr. W. P. Jacobs. This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Halaban, Ruth

doi: 10.1104/pp.43.12.1887pmid: 16656986

Abstract The phase response curve for the circadian rhythm of leaf movement of Coleus blumei x C. frederici, a short day plant, is generally similar to those reported for other organisms. An increase in the duration of the light signal caused an increase in the extreme values of the phase response curve and shortened the time for transition from maximum delays to maximum advances. Experiments with 2 light signals showed that the overt rhythm of leaf movement represents the rhythm of the light sensitive oscillator even during the transient period that followed the first light signal. A temperature decrease of 7° for 8 hr caused only a transient phase shift in the following 2 cycles but not in the steady state. The combination of such a temperature decrease and a light signal showed that only the overt rhythm of leaf movement was disturbed by the temperature decrease whereas the light sensitive oscillator was free running. A temperature decrease of 11° for 10 hr caused a steady state phase shift and affected the light sensitive oscillator as well. 1 The material presented in this paper is part of a dissertation submitted to the Department of Biology Princeton University in partial fulfillment of the requirements for the degree of Doctor of Philosophy. 2 Supported in part by a NSF grant to Dr. W. P. Jacobs. This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Halaban, Ruth

doi: 10.1104/pp.43.12.1894pmid: 16656987

Abstract The flowering response of Coleus frederici and Coleus blumei x C. frederici is dependent on the photoperiod; both plants have a critical day length of about 12 hr. The inductive phase, defined as the period when light signals inhibit floral development, started 10 hr after the onset of darkness under 4 and 8-hr photoperiods, and 8 hr after the onset of darkness under a 12-hr photoperiod. However, a fixed temporal relationship between the inductive phase and the minimum leaf position was observed for Coleus frederici. The inductive phase always started 5 hr after the minimum leaf position. This evidence supports the theory that a circadian clock participates in the time measurement process of photoperiodic floral induction. 1 This work was partially supported by a NSF grant to Dr. W. P. Jacobs. 2 The material presented here is a part of a dissertation submitted to the Department of Biology of Princeton University in partial fulfillment of the requirements for the degree of Doctor of Philosophy. This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Murata, Takao; Akazawa, T.; Fukuchi, Shikiko

doi: 10.1104/pp.43.12.1899pmid: 16656988

Abstract Time-sequence analyses of carbohydrate breakdown in germinating rice seeds shows that a rapid breakdown of starch reserve in endosperm starts after about 4 days of germination. Although the major soluble carbohydrate in the dry seed is sucrose, a marked increase in the production of glucose and maltooligosaccharides accompanies the breakdown of starch. Maltotriose was found to constitute the greatest portion of the oligosaccharides throughout the germination stage. α-Amylase activities were found to parallel the pattern of starch breakdown. Assays for phosphorylase activity showed that this enzyme may account for much smaller amounts of starch breakdown per grain, as compared to the amounts hydrolyzed by α-amylase. There was a transient decline in the content of sucrose in the initial 4 days of seed germination, followed by the gradual increase in later germination stages. During the entire germination stage, sucrose synthetase activity was not detected in the endosperm, although appreciable enzyme activity was present in the growing shoot tissues as well as in the frozen rice seeds harvested at the mid-milky stage. We propose the predominant formation of glucose from starch reserves in the endosperm by the action of α-amylase and accompanying hydrolytic enzyme(s) and that this sugar is eventually mobilized to the growing tissues, shoots or roots. 1 This research was supported in part by a research grant of ARS, USDA, under the PL 480 Program (No. FG-JA-126). This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Klucas, Robert V.; Koch, Burton; Russell, Sterling A.; Evans, Harold J.

doi: 10.1104/pp.43.12.1906pmid: 16656989

Abstract The nitrogenase system in cell-free extracts of soybean nodule bacteroids was fractionated into 2 components by use of protamine sulfate or polypropylene glycol precipitation followed by chromatography on DEAE-cellulose. Iron and molybdenum were concentrated in 1 fraction and iron in the other. Combination of fractions resulted in a striking stimulation in activity relative to the activity of individual fractions. The effect of different proportions of the 2 fractions on specific activities was studied. The ratios of the rates of reduction of acetylene and N2 by extracts or fractions of different purities were relatively constant. Extracts or fractions retained most of their nitrogenase activities when stored in liquid N2. 2 United States Public Health Service Fellow (GM 35-348-01). 1 This research was supported by NSF grant GB5185X and by the Oregon Agricultural Experiment Station (Technical Paper No. 2532). This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Hutchin, Maxine E.; Vaughan, Burton E.

doi: 10.1104/pp.43.12.1913pmid: 5725599

Abstract Root segments of vetch, barley, and pine were exposed to a nutrient solution containing 85Sr and 45Ca tracers. Translocation was measured from solutions containing stable ions at concentrations of 2.5 mm Ca, and at either 0.5 mm or 2.5 mm Sr. Polar transport was established between 12 and 18 hr in barley, and between 16 and 22 hr in vetch. Acropetal transport remained below 5% of basipetal transport of tracer during these intervals. Transport in both vetch and barley usually declined before an elapsed time of 24 hr unlike corn, which maintained its steady state beyond 24 hr. Pine was radically different in that it showed no difference between acropetal and basipetal transport rates and had very low rates. Sr transport in all plants studied to date paralleled that of Ca and the ratio Sr:Ca transported was equal to the ratio Sr:Ca in the nutrient. In vetch, stable Ca transport was reduced to one-fifth when Sr concentration was increased from 0.5 mm to 2.5 mm. Yet stable Sr transport did not change, indicating that the effect on transport was not due to competitive inhibition. A similar effect was less pronounced in barley, but could not be detected in pine. The magnitude of the transport rates varied considerably among the various species, corn having the greatest followed by barley, vetch, and pine in decreasing order. Transport did not correlate with root weight or surface area; it amounted to from 0.03 to 0.60 nanomoles per hr in these experiments as compared to 7 nanomoles per hr previously established in corn (in all cases, 55 mm segments, sectioned 10 mm from apex). 1 Work supported jointly under Office of Civil Defense and under Director of Navy Laboratories, Independent Exploratory Development Program. This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Ting, Irwin P.

doi: 10.1104/pp.43.12.1919pmid: 16656990

Abstract Phosphoenolpyruvate carboxylase was purified from corn root tips about 80-fold by centrifugation, ammonium sulfate fractionation, and anion exchange and gel filtration chromatography. The resulting preparation was essentially free from malate dehydrogenase, isocitrate dehydrogenase, malate enzyme, NADH oxidase, and pyruvate kinase activity. Kinetic analysis indicated that l-malate was a noncompetitive inhibitor of P-enolpyruvate carboxylase with respect to P-enolpyruvate (KI = 0.8 mm). d-Malate, aspartate, and glutamate inhibited to a lesser extent; succinate, fumarate, and pyruvate did not inhibit. Oxaloacetate was also a noncompetitive inhibitor of P-enolpyruvate carboxylase with an apparent KI of 0.4 mm. A comparison of oxaloacetate and l-malate inhibition suggested that the mechanisms of inhibition were different. These data indicated that l-malate may regulate CO2 fixation in corn root tips by a feedback or end product type of inhibition. 1 Supported in part by NSF Grant GB-6735. This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Shimabukuro, R. H.

doi: 10.1104/pp.43.12.1925pmid: 16656991

Abstract The metabolism of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) in the resistant species, corn (Zea mays L.) and sorghum (Sorghum vulgare Pers.) was not the same. In corn, atrazine was metabolized via both the 2-hydroxylation and N-dealkylation pathways while sorghum metabolized atrazine via the N-dealkylation pathway. Atrazine metabolism in corn yielded the metabolites, 2-hydroxy-4-ethylamino-6-isopropylamino-s-triazine (hydroxyatrazine), 2-hydroxy-4-amino-6-isopropylamino-s-triazine (hydroxycompound I), and 2-hydroxy-4-amino-6-ethylamino-s-triazine (hydroxycompound II). None of these hydroxylated derivatives appeared as metabolites of atrazine in sorghum. Hydroxycompounds I and II were formed in 2 ways in corn: (1) by benzoxazinone-catalyzed hydrolysis of 2-chloro-4-amino-6-isopropylamino-s-triazine (compound I) and 2-chloro-4-amino-6-ethylamino-s-triazine (compound II) that were formed by N-dealkylation of atrazine and (2) by N-dealkylation of hydroxyatrazine, the major atrazine metabolite in corn. The interaction of the 2-hydroxylation and N-dealkylation pathways in corn results in the formation of the 3 hydroxylated non-phytotoxic derivatives of atrazine. This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Klepper, Betty

doi: 10.1104/pp.43.12.1931pmid: 16656992

Abstract The dynamic relationship between the rates of water loss and uptake controls plant water status. Marked diurnal variations in water potential of both leaves and fruit occurred in all plants studied. Variations in water status during the day were most clearly related to changes in evaporative demand of the air and were different for the east and west sides of a tree. At night, the plant water potential reflected the soil moisture status. Changes in the water potential of pear fruit were correlated with changes in fruit diameter. Since water loss from fruit occurred mostly through the pedicel into the xylem of the tree, the fruit could be used as a crude gauge of xylem water potential, which also showed dramatic changes during the day. 1 Present address: Department of Botany and Plant Pathology, Auburn University, Auburn, Alabama 36830. This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Sun, Elena; Barr, Rita; Crane, F. L.

doi: 10.1104/pp.43.12.1935pmid: 16656993

Abstract Plastoquinones A and C have been found in all classes of algae, including representatives of greens, yellow-greens, blue-greens, reds, browns and the flagellate, Euglena. Plastoquinone C from red and brown algae can be separated into 6 different types. An additional plastoquinone C has been found in Gigartina and Rhydomela. From chromatographic evidence this may be equivalent to plastoquinone Co, a C type with a hydroxyl group on the first isoprene unit of the terpenoid sidechain of this substituted benzo-quinone. The ubiquinone, vitamin K and α-tocopherylquinone content of several algae is also reported. The presence of plastoquinone A in all green plants and many algae indicates that it may be a functional element in photosynthesis. Our study shows that plastoquinone C is more regularly present in algae than has been previously shown. This content is only available as a PDF. © 1968 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)