Volatile Metabolites Controlling Germination in Buried Weed Seeds

Holm, Robert E.

doi:10.1104/pp.50.2.293

Cited by 129 publications

(97 citation statements)

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“…It is interesting to note that, whenever ChE activity was detected in plants, eserine was much less effective in vitro compared to animal ChE (27,28). On the other hand, when applied in vivo, eserine was active in relatively low concentrations even in plant tissues (8,13,16). This discrepancy might be explained by the possibility that eserine is being ionized in vivo and this corresponds to the increased activity observed in vivo.…”

Section: Discussionmentioning

confidence: 63%

“…Though )M PLANT TISSUES. I 527 the physiological role of this enzyme has not yet been established and there is no evidence that ACh is the natural substrate of the enzyme, there are some data which suggest that the enzyme functions as AChE to regulate the amount of ACh in plant tissues (8,13,15).…”

Section: Discussionmentioning

confidence: 99%

“…Other workers (8,9,13) have also reported that whenever ACh was found to play a role in physiological processes in plant tissues, ChE inhibitors increased the effects of ACh or were essential for getting any effects of ACh. It was for this reason that we became interested in ChE in plant tissues.…”

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confidence: 99%

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Cholinesterases from Plant Tissues

Riov¹,

Jaffe²

1973

Plant Physiol.

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A cholinesterase was purified 36-fold from mung bean (Phaseolus aureus) roots by a combination of differential extraction media and gel filtration. The enzyme could be effectively extracted only by high salt concentration, indicating that it is probably membrane-bound. Methods used for assaying animal cholinesterases were tested, two of which were adapted for use with the bean cholinesterase. The bean enzyme hydrolyzed choline and noncholine esters but showed its highest affinity for acetylcholine and acetylthiocholine. The pH optimum was 8.5 for acetylthiocholine and 8.7 for acetylcholine. The Michaelis constants were 72 and 84 AM for acetylcholine and acetylthiocholine, respectively. The cholinesterase was relatively insensitive to eserine (half-maximum inhibition at 0.42 mM) but showed high sensitivity to neostigmine (half-maximum inhibition at 0.6 AM). Other animal cholinesterase inhibitors were also found to inhibit the bean enzyme but most of them at higher concentrations than are generally encountered. Choline stimulated enzymatic activity. The molecular weight of the cholinesterase was estimated to be greater than 200,000, but at least one smaller form was observed. It is suggested that the large form of cholinesterase is converted to the smaller form by proteolysis.Acetylcholine has been shown to participate in phytochrome-mediated processes in bean roots (16), and the results obtained in the above work suggested that bean roots might contain a cholinesterase which functions to regulate the content of ACh' in roots. Other workers (8, 9, 13) have also reported that whenever ACh was found to play a role in physiological processes in plant tissues, ChE inhibitors increased the effects of ACh or were essential for getting any effects of ACh. It The chemicals used in this work were obtained from the following sources: choline chloride, acetylcholine chloride, acetylthiocholine iodide, propionylthiocholine iodide, butyrylthiocholine iodide, DTNB, eserine (physostigmine) sulfate, neostigmine (prostigmine) bromide, bovine serum albumin, Triton X-100, and Sephadex G-200 from Sigma Chemical Co.; acetyl-I-'4C-choline chloride (9.2 mc/mmole) and Aquasol

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Section: Discussionmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 99%

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Cholinesterases from Plant Tissues

Riov¹,

Jaffe²

1973

Plant Physiol.

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“…Além do efeito térmico, a cobertura apresenta outros efeitos que podem ser importantes quando se trata do controle das plantas daninhas. A própria barreira física que o plástico representa, alterações na atmosfera do solo quanto ao balanço entre CO2 e O2 (Egley & Duke, 1965;Grant Lipp & Ballard, 1959;Horowitz et al, 1983;Rubin & Benjamin, 1984) e quanto a manutenção de compostos voláteis sob a cobertura (Egley & Duke, 1965;Holm, 1972;Rubin & Benjamin, 1983;Taylorson, 1979) que podem afetar a germinação de sementes.…”

Section: Introductionunclassified

Efeitos da solarização do solo através de plástico transparente sobre o desenvolvimento da tiririca (Cyperus rotundus)

1995

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RESUMOUm ensaio foi conduzido em condições de campo, durante o verão, com o objetivo de avaliar o potencial da técnica de solarização do solo no controle da tiririca (Cyperus rotundus L.). O delineamento experimental utilizado foi o de blocos casualizados com três repetições, e os tratamentos num esquema fatorial 2 X 2 X 3, sendo duas situações de cobertura (com e sem plástico transparente de 300 µm de espessura), dois estádios de desenvolvimento da planta daninha (vegetativo e florescimento) e três períodos de cobertura com plástico (15, 30 e 60 dias). A temperatura do solo sob solarização teve um aumento médio de 4,3°C em relação à testemunha, atingindo valores superiores a 50°C em determi nados horários. Observou-se, também, um acúmulo da ordem de 400 % nos teores de CO 2 na atmosfera do solo solarizado. Nessas condições houve inibição da brotação dos tubérculos e diminuição no peso de matéria seca de todas as partes estudadas da planta. Houve redução na taxa de multiplicação dos tubérculos, reduzindo-a de 1:11 para 1:4, quando coberta no estádio vegetativo e para 1:9 quando a cobertura se realizou no estádio de florescimento. Houve, ainda, diminuição na ordem de 20% na viabilidade dos tubérculos remanescentes.Palavras-chave: Plantas daninhas, controle físico, temperatura, biologia, estratégia reprodutiva. ABSTRACT Th e ef fe ct s of so il so la ri za ti on wi th tr an sp ar en t pl as ti c on pu rp le nutsedge (Cyperus rotundus)The research was conducted under field conditions during the summer period, to evaluate the solarization effect on purple nutsedge (Cyperus rotundus) control. The experimental design was randomized blocks with three replications. The treatments were arranged in a factorial scheme 2 X 2 X 3, with two cover conditions (with and without transparent plastic sheet, 300 µm thickness), two periods of covering (vegetative and flower stages), and three cover periods (15, 30 and 60 days). The soil temperature under solarization was 4.3°C higher than the control, reaching more than 50°C at certain times of day. An increase of 400% was observed in the CO2 concentration in the atmosphere of solarized soil. Under these conditions the tuber sprouting was inhibited and the dry weight of all parts of the plant was decreased. The rate of tuber multiplication was decreased from 1:11 to 1:4 when the plant was covered at the vegetative stage, and to 1:9 when it was covered at the repr oductive stage. A decrease of 20% in tuber viability was also observed.

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“…Since the pioneer work on leaf leachates and root exudates (30)(31)(32)(33)(34)(35), an array of literature confirms that plants loose many metabolites as well as allelochemicals. There is compelling evidence that a wide range of allelochemicals present in seeds contribute to the prevention of seed decay (1,36), and a few experiments illustrate that inhibitors may leach from seeds (37)(38)(39)(40)(41). Likewise, even during their limited life span, the various microorganisms do not retain all that they produce.…”

Section: Allelochemical Release and Transfersmentioning

confidence: 99%

Allelopathy: Current Status and Future Goals

Einhellig

1994

ACS Symposium Series

148

112

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The phenomenon of allelopathy encompasses all types of chemical interactions among plants and microorganisms. Several hundred different organic compounds (allelochemicals) released from plants and microbes are known to affect the growth or aspects of function of the receiving species. Many new allelochemicals have been identified in recent years and it has become clear that the actions of allelochemicals are important features characterizing the interrelationships among organisms. These compounds influence patterns in vegetational communities, plant succession, seed preservation, germination of fungal spores, the nitrogen cycle, mutualistic associations, crop productivity, and plant defense. Allelopathy is tightly coupled with competition for resources and stress from disease, temperature extremes, moisture deficit, and herbicides. Such stresses often increase allelochemical production and accentuate their action. Allelopathic inhibition typically results from a combination of allelochemicals which interfere with several physiological processes in the receiving plant or microorganism. Other than the autecological study of specific species, there are persistent challenges in allelopathy to determine the mechanism of action of compounds, isolate new compounds, evaluate environmental interactions, and understand activity in the soil. New frontiers will focus on ways to capitalize on allelopathy to enhance crop production and develop a more sustainable agriculture, including weed and pest control through crop rotations, residue management, and a variety of approaches in biocontrol. Other goals are to adapt allelochemicals as herbicides, pesticides, and growth stimulants, modify crop genomes to manipulate allelochemical production, and better elucidate chemical communications that generate associations between microorganisms and higher plants. 0097 ALLELOPATHY: ORGANISMS, PROCESSES, AND APPLICATIONSThe writings of some natural philosophers that date back more than two millenniums show that they recognized chemical influences in nature (1). However, it is the evidence accumulated over the last several decades which has established that external roles for biochemicals, meaning roles that do not directly affect the basic physiology of the producing organism, are pervasive themes characterizing the interrelationships among organisms. This realization does not diminish the respective importance that competition for resources has on the relative success of an organism or a species. Instead, chemical ecology extends our dimensions of understanding and provides new insights into the intricacies of interchanges that occur in an ecosystem, community, or population.Allelopathy, a subset within the broader scope of chemical ecology, is concerned with effects that chemicals of plant or microbial origin have on growth, development, and distribution of other plants and microorganisms in natural communities or agricultural systems. The aims of this overview chapter are to provide a synthesis of the scope of allelopathy, suggest gen...

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Volatile Metabolites Controlling Germination in Buried Weed Seeds

Cited by 129 publications

References 12 publications

Cholinesterases from Plant Tissues

Cholinesterases from Plant Tissues

Efeitos da solarização do solo através de plástico transparente sobre o desenvolvimento da tiririca (Cyperus rotundus)

Allelopathy: Current Status and Future Goals

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