摘要:

After 3 days of exposure to 10−3and 10−4M decenylsuccinic acid, winter wheat plants wilted and died. Decenylsuccinate at 10−3M inhibited32P uptake by barley roots and wheat roots and resulted in significant (P≤0.05) leakage of previously absorbed32P and total phosphorus (barley roots). Decenylsuccinate effects on32P uptake and retention were attributed to increased permeability resulting from injury. Decenylsuccinate at 10−4M did not inhibit root uptake of32P but decreased movement into the shoot. This could be interpreted as an indication of reduced transpiration or inhibition of32P loading into the transpiration stream. Decenylsuccinate did not increase cold hardiness in winter wheat in a nonhardening en

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

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 (10−6M) 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 germinatio

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

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 10−4mGA3decreased 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 GA3is 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 GA3in a range from 10−8to 10−4m. At 10−3m, GA3slightly 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 10−4mGA3over a period of 40 hours, nor did activity ofα-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. GA3had 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 10−4mGA3, as measured by the incorporation ofl-phenylalanine-U-14C or by experiments with14C- and3H- labeledl-phenylalanine

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

Extracts of seeds of pumpkin (Cucurbita pepoLinn.) contain three chromatographically distinguishable cytokinins which are held on Dowex 50-W and are extractable by ethanol andn-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 RFvalues of the other two active compounds do not match with those of any of the known natural cytokinins.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

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.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

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 ofp-chloromercuribenzoic acid orN-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 sodiumβ-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

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

The effect of gibberellin A3(10−4m) and abscisic acid (10−4m), applied separately and together, on incorporation of3H-thymidine and3H-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 A3slightly promoted synthesis of DNA and RNA, and abscisic acid essentially blocked such synthesis, in both the presence and absence of gibberellin

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

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 inhibits32P 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 translati

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

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 measuredin 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.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB

摘要:

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-soluble14C from treated corn roots and tobacco pith gives no indication of degradation. Very little14C-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% of14C-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.

ISSN:0032-0889    

出版商:American Society of Plant Biologists    

年代:1970

数据来源: ASPB