Plant Physiology

Green, D. G.; Ferguson, W. S.; Warder, F. G.

doi: 10.1104/pp.45.1.1pmid: 16657270

Abstract After 3 days of exposure to 10−3 and 10−4 M decenylsuccinic acid, winter wheat plants wilted and died. Decenylsuccinate at 10−3 M inhibited 32P uptake by barley roots and wheat roots and resulted in significant (P ≤ 0.05) leakage of previously absorbed 32P and total phosphorus (barley roots). Decenylsuccinate effects on 32P uptake and retention were attributed to increased permeability resulting from injury. Decenylsuccinate at 10−4 M did not inhibit root uptake of 32P but decreased movement into the shoot. This could be interpreted as an indication of reduced transpiration or inhibition of 32P loading into the transpiration stream. Decenylsuccinate did not increase cold hardiness in winter wheat in a nonhardening environment. This content is only available as a PDF. © 1970 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)

Mandal, N. C.; Biswas, B. B.

doi: 10.1104/pp.45.1.4pmid: 16657276

Abstract The degradation of phytin in germinating mung bean seeds has been found to be associated with the increased activity of phytase in the cotyledon. In the differentiated embryo the increase of this activity is very low all throughout the growth periods studied. Phytase appears in the cotyledon during germination. No activity has been detected in the cotyledons of unsoaked seeds. Cycloheximide (10−6 M) inhibits the appearance of phytase by 61% during 24 and 48 hours after the start of germination. This phytase increase is dependent on the synthesis of new RNA in the cotyledon. Synthesis of DNA is not detected in the cotyledon during germination. 1 Supported by United States Department of Agriculture Grant F.G. In-321. This content is only available as a PDF. © 1970 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)

Clegg, M. D.; Rappaport, Lawrence

doi: 10.1104/pp.45.1.8pmid: 16657283

Abstract The rest period of the potato tuber was studied in relation to certain biochemical changes that are induced by gibberellic acid (GA3). The concentration of reducing sugars in excised plugs with buds treated with 10−4m GA3 decreased in the first 4 hours after treatment and then rapidly increased up to 70 hours. The pattern in control buds was similar, but the changes occurred more slowly. The response to GA3 is temperature-dependent and is not limited to any particular tissue of the tuber. The concentration of reducing sugars in excised buds increased proportionally to the log of the concentration of GA3 in a range from 10−8 to 10−4m. At 10−3m, GA3 slightly inhibited production of reducing sugars. Malonate inhibits the initial decrease and the subsequent increase in reducing sugars in control buds, but not the increase induced by GA3. Total protein in buds was not influenced by 10−4m GA3 over a period of 40 hours, nor did activity of α-amylase increase significantly until 20 hours after beginning of treatment. Invertase activity was present initially and, in the presence of GA3, increased after 20 hours. GA3 had no effect on starch phosphorylase activity, which was always present and remained steady over the 20-hour test period. In short term experiments the rate of protein synthesis and synthesis of specific protein fractions were not affected by 10−4m GA3, as measured by the incorporation of l-phenylalanine-U-14C or by experiments with 14C- and 3H- labeled l-phenylalanine or l-leucine. 3 Present address: Department of Agronomy, University of Nebraska, Lincoln, Nebraska 68503. 1 This investigation was supported in part by Research Grant GM-12885 from the United States Public Health Service. 2 Submitted by M. D. C. to the Graduate Division, University of California, Davis, in partial fulfillment of the requirements for the degree of Doctor of Philosophy. This content is only available as a PDF. © 1970 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)

Gupta, Geeta R. P.; Maheshwari, S. C.

doi: 10.1104/pp.45.1.14pmid: 16657272

Abstract Extracts of seeds of pumpkin (Cucurbita pepo Linn.) contain three chromatographically distinguishable cytokinins which are held on Dowex 50-W and are extractable by ethanol and n-butanol. Two of the active factors are precipitable by silver nitrate at acidic pH. The chromatographic behavior and the spectral characteristics of one of these cytokinins are similar to those of zeatin. However, the RF values of the other two active compounds do not match with those of any of the known natural cytokinins. This content is only available as a PDF. © 1970 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)

de la Fuente, R. K.; Leopold, A. C.

doi: 10.1104/pp.45.1.19pmid: 16657273

Abstract Evidences from experiments with stem sections of sunflower seedlings suggest that the transport of auxin may be limited by a restricted pool size of transportable auxin and restrictions in the availability of transport sites. A steady state of transport is observed over a range of lengths of stem sections, and over a wide range of auxin contents. The capacity of the sections to transport a pulse of auxin declines with aging after cutting, 50% decline occurring at about 10+ hours; the transportability of a pulse of auxin declines rapidly after the completion of uptake, 50% decline occurring at about 1 hour. A chase treatment with unlabeled auxin does not alter transport, but a pretreatment with auxin depressed subsequent transport for about 1 hour. In depleted tissues such pretreatment is not inhibitory but rather is promotive of transport. The interpretation offered is that transport is limited by the pool size and transport sites, and roles for these factors are suggested in relation to the auxin transport gradient and the tropistic responses. 2 Present address: Biological Sciences Department, Kent State University, Kent, Ohio. 1 Journal paper No. 3721, Agricultural Experiment Station, Purdue University, Lafayette, Indiana. Supported in part by a grant from the National Science Foundation. This content is only available as a PDF. © 1970 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)

Sabnis, Dinkar D.; Gordon, Mildred; Galston, Arthur W.

doi: 10.1104/pp.45.1.25pmid: 4245003

Abstract When samples of pea tendril tissue were incubated in the Wachstein-Meisel medium for the demonstration of adenosine triphosphatases, deposits of lead reaction product were localized between the membranes of the chloroplast envelope. The presence of Mg2+ was necessary for adenosine triphosphatase activity, and Ca2+ could not substitute for this requirement. Varying the pH of incubation to 5.5 or 9.4 inhibited enzyme activity, as did the addition of p-chloromercuribenzoic acid or N-ethylmaleimide. The adenosine triphosphatase was apparently inactivated or degraded when the plants were grown in the dark for 24 hours prior to incubation. The enzyme was substrate-specific for adenosine triphosphate; no reaction was obtained with adenosine diphosphate, uridine triphosphate, inosine triphosphate, p-nitrophenyl phosphate, and sodium β-glycerophosphate. Sites of nonspecific depositions of lead are described. The adenosine triphosphatase on the chloroplast envelope may be involved in the light-induced contraction of this organelle. 2 Present address: Botany Department, University of Aberdeen, Aberdeen, Scotland. 3 Present address: Department of Anatomy, Yale University School of Medicine, New Haven, Connecticut 06510. 1 This investigation was supported by a National Science Foundation grant to A. W. Galston. This content is only available as a PDF. © 1970 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)

Shih, C. Y.; Rappaport, Lawrence

doi: 10.1104/pp.45.1.33pmid: 16657274

Abstract The effect of gibberellin A3 (10−4m) and abscisic acid (10−4m), applied separately and together, on incorporation of 3H-thymidine and 3H-uridine into DNA and RNA of buds from freshly harvested potatoes was investigated. In some treatments apical buds in intact tubers were treated three times daily for 3 days with test solution before the buds were excised and treated an additional 12 hours in Petri dishes. In other treatments, untreated buds were excised and treated 12 hours. Irrespective of length of treatment, gibberellin A3 slightly promoted synthesis of DNA and RNA, and abscisic acid essentially blocked such synthesis, in both the presence and absence of gibberellin A3. 2 Present address: Department of Botany, University of Iowa, Iowa City, Iowa. 1 Supported in part by a University cancer research grant and by a research grant (GM 12885) from the United States Public Health Service. This content is only available as a PDF. © 1970 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)

Walton, D. C.; Soofi, G. S.; Sondheimer, E.

doi: 10.1104/pp.45.1.37pmid: 16657275

Abstract Abscisic acid (ABA) is an effective inhibitor of cell elongation in excised embryonic bean axes whether added prior to or after the initiation of cell elongation. Zeatin partially reverses this growth inhibition. ABA inhibits 32P incorporation into ribosomal RNA, transfer RNA, and DNA but not into the tenaciously bound fraction of elongating axes in a manner resembling 5-fluorouracil, a compound which does not inhibit axis growth. The methylated albumin on kie-selguhr elution profiles of nucleic acids obtained from axes treated with either ABA, 5-fluorouracil, or a combination of the two are similar, and zeatin treatment has little apparent effect on these results. Our results suggest that the inhibition of growth in the axes by ABA is not due to its inhibition of DNA synthesis. ABA (1.9 × 10−5m) inhibits growth by 30 and 70% within 1 and 2 hours, respectively, after its addition to elongating axes. Its kinetics of inhibition are similar to those obtained with cycloheximide, and both compounds are more effective than 8-azaadenine. Based on these results, it is suggested that one possible effect of ABA may be at the level of translation. 2 Present address: Department of Radiation Biology, State University of New York Medical Center, Syracuse, New York. 1 This work was partly supported by Forest Service Grant 3-4040 and by National Science Foundation Grants GB 4145 and GB 4262. This content is only available as a PDF. © 1970 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)

Holm, Robert E.; O'Brien, T. J.; Key, J. L.; Cherry, J. H.

doi: 10.1104/pp.45.1.41pmid: 16657277

Abstract Soybean seedlings treated with ethylene exhibited small increases in ribonucleic acid content in the elongating section of the hypocotyl. Chromatin isolated from the elongating section of ethylene-treated seedlings showed a 35 to 60% increase in the capacity for RNA synthesis. The ethylene-induced response was saturated at 1 microliter/liter of ethylene and was fully expressed after 3 hours. Auxin caused marked accumulation of RNA and DNA in the elongating and basal tissue of the hypocotyl. Chromatin isolated from these auxin-treated tissues showed an 8- to 10- fold increase in RNA synthetic capacity as measured in vitro. Ethylene added with auxin reduced the auxin enhancement of nucleic acid synthesis in the elongating and basal tissues. Both ethylene and auxin treatment of the seedlings inhibited nucleic acid accumulation and chromatin activity in the apical tissue. Ethylene did not appear to mediate the auxin effects on nucleic acid synthesis in soybean hypocotyl with the possible exception of inhibition in the apical tissue. The RNA which was synthesized by chromatin isolated from control and auxin- and ethylene-treated tissues was characterized by nearest neighbor analyses. The nearest neighbor frequencies of the RNA products synthesized by chromatin isolated from auxin- and ethylene-treated hypocotyl tissue were different from each other and different from the control RNA product. Seedlings treated in sealed containers exhibited growth, RNA, and DNA responses, especially to ethylene, different from those of seedlings treated in continuous flow containers. 3 Present address: Diamond Shamrock Corporation, T. R. Evans Research Center, P. O. Box 348, Painesville, Ohio 44077. 4 Present address: Department of Botany, University of Georgia, Athens, Georgia. 1 Research supported by National Institutes of Health grant, formerly GM 10157, now CA 10932 (J. L. K.) and a grant from the National Science Foundation (GB-7415 to J. H. C.). 2 Purdue University AES Journal Paper 3737. This content is only available as a PDF. © 1970 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)

Noodén, Larry D.

doi: 10.1104/pp.45.1.46pmid: 16657278

Abstract Maleic hydrazide (MH) is taken up by corn and pea seedling roots and bound to some material which is insoluble in 80% ethanol or 5% trichloroacetic acid. 14C-MH is stable metabolically; chromatography of the 80% ethanol-soluble 14C from treated corn roots and tobacco pith gives no indication of degradation. Very little 14C-MH is bound in the zone of cell division (where MH acts to inhibit root elongation) or even in the region of cell enlargement in corn roots and most is bound 1 or more centimeters behind the tip. Likewise, very little MH is bound in corn coleoptile and tobacco pith sections. About 90% of 14C-MH bound in corn roots is associated with large particles which may be cell wall fragments. The binding is blocked by azide and dinitrophenol, indicating a requirement for metabolic energy; however, inhibitors of protein synthesis (chloramphenicol, puromycin, cycloheximide) and DNA synthesis (fluorodeoxyuridine) do not inhibit binding. Only very small amounts of MH are bound in root homogenates, providing further evidence that the binding process is active. Once the MH is bound in the roots, the complex is stable for at least 1 week. Treatment with 2-aminoethanol releases MH. 1 This work was supported initially by Institutional Research Grant IN-40G to the University of Michigan from the American Cancer Society, by a grant from the H. H. Rackham School of Graduate Studies, and later by National Science Foundation Grant GB-5502. This content is only available as a PDF. © 1970 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)