Ethylene biosynthesis and related physiological changes in Penicillium digitatum-infected grapefruit (Citrus paradisi)

Achilea, O.; Chalutz, E.; Fuchs, Yoram; Rot, I.

doi:10.1016/0048-4059(85)90013-x

Cited by 30 publications

(16 citation statements)

References 25 publications

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“…The lower infection level was likely a consequence of less inoculum (50 versus 100 g in the previous studies), earlier harvest dates, and a higher average concentration of P in roots (e.g. low P NM plants averaged 1 The effect of VAM infection on production of leachable phenolics from roots is illustrated in Figure 7B. Levels of leachable phenolics were not significantly affected by P nutrition or an interaction between VAM and [P].…”

Section: Resultsmentioning

confidence: 88%

“…Impairment of ACCOx activity has been observed in other host-parasite interactions, such as during infection of grapefruit by Penicillium digitatum (1). Related studies have shown that inhibition of either ACC synthase or ACCOx activity can result in redirection of S-adenosylmethionine into the polyamine biosynthetic pathway and, as a consequence, result in further reductions of ACCox activity (14).…”

Section: Discussionmentioning

confidence: 98%

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Resistance Responses of Potato to Vesicular-Arbuscular Mycorrhizal Fungi under Varying Abiotic Phosphorus Levels

McArthur¹,

Knowles²

1992

Plant Physiol.

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In mycorrhizal symbioses, susceptibility of a host plant to infection by fungi is influenced by environmental factors, especially the availability of soil phosphorus. This study describes morphological and biochemical details of interactions between a vesicular-arbuscular mycorrhizal (VAM) fungus and potato (Solanum tuberosum L. cv Russet Burbank) plants, with a particular focus on the physiological basis for P-induced resistance of roots to infection. Root infection by the VAM fungus Glomus fasciculatum ([Thaxt. sensu Gerdemann] Gerdemann and Trappe) was extensive for plants grown with low abiotic P supply, and plant biomass accumulation was enhanced by the symbiosis. The capacity of excised roots from P-deficient plants to produce ethylene in the presence or absence of exogenous 1-amino cyclopropane-1-carboxylic acid (ACC) was markedly reduced by VAM infection. This apparent inhibition of ACC oxidase (ACCOX) activity was localized to areas containing infected roots, as demonstrated in split-root studies. Furthermore, leachate from VAM roots contained a potent water-soluble inhibitor of ethylene generation from exogenous ACC by nonmycorrhizal (NM) roots. The leachate from VAM-infected roots had a higher concentration of phenolics, relative to that from NM roots. Moreover, the rates of ethylene formation and phenolic concentration in leachates from VAM roots were inversely correlated, suggesting that this inhibitor may be of a phenolic nature. The specific activity of extracellular peroxidase recovered in root leachates was not stimulated by VAM infection, although activity on a fresh weight basis was significantly enhanced, reflecting the fact that VAM roots had higher protein content than NM roots. Polyphenol oxidase activity of roots did not differ between NM and VAM roots. These results characterize the low resistance response of P-deficient plants to VAM infection. When plants were grown with higher abiotic P supply, the relative benefit of the VAM symbiosis to plant growth decreased and root infection was lower. The in vivo ACCOX activity was also greater in roots of plants grown on high levels of P compared with those grown on low levels, although the influence of VAM infection was partially to counteract the nutritional effect of P on ACCOX activity. Similar to ACCOX activity, extracellular peroxidase activity of roots increased linearly with increasing abiotic P supply, thus indicating a greater potential for resistance to VAM infection. These findings suggest that VAM fungi may alter phenolic metabolism of roots so as to hinder ethylene production and the root's ability to invoke a defense response. Raising the abiotic P supply to plants at least partially restores the capacity of roots to produce ethylene and may, in this way, increase the root's resistance to VAM infection. The VAM2 fungi are a small and distinct group of obligate, symbiotic fungi that are capable of association with roots of most terrestrial vascular plants (20). In exchange for photoassimilates, VAM fungi contribute to t...

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Section: Resultsmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 98%

Resistance Responses of Potato to Vesicular-Arbuscular Mycorrhizal Fungi under Varying Abiotic Phosphorus Levels

McArthur¹,

Knowles²

1992

Plant Physiol.

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“…Using ethylene producing and nonproducing isolates, Achilea et al (1,2) concluded that ethylene production by P. digitatum-infected fruit was mostly or entirely of fungal origin, and they showed that the biochemical pathway for the production of ethylene in P. digitatum is unlike the pathway in higher plants.…”

Section: Resultsmentioning

confidence: 99%

Cotton Fleahopper and Associated Microorganisms as Components in the Production of Stress Ethylene by Cotton

Martin

Morgan²,

Sterling³

et al. 1988

Plant Physiol.

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Excised cotton terminal buds incubated with adults or nymphs of the cotton fleahopper (CFH), Pseudatomoscelis seriatus (Reuter), produced ethylene at theoretical abscission-inducing rates by 24 h after introduction of the insect. Inoculation of cotton shoot tips with three microorganisms commonly associated with CFH and cotton in all cases promoted ethylene production to theoretical abscission-inducing rates by 24 h after inoculation. CFH alone or injection of microorganisms consistently caused cotton shoot tips to darken and become soft. These changes paralleled the rise in ethylene production and did not occur in control shoot tips. Of the three microorganisms, Xanthomonas campestris pv malvacearum (Smith) Dye (XCM) produced little ethylene when grown in culture, while the two fungi, Peneilium purpurogenum Stoil and P. glabrum (Wehmer) Westling, produced higher levels. The parallel between plant response to CFH, XCM, and CFH-+ XCM suggests a sinilar mechanism of ethylene induction by these two stress agents. Since a portion of the CFH were devoid of microorganisms, yet their impact on ethylene production by cotton tissue was uniform, we propose that the primary mechanism of ethylene induction involves the insect's salivary fluids which contain cell wall hydrolyzing enzymes.plant of the CFH influences the insect's microflora and the extent of its contamination (18); and (d) lab-reared CFH generally contain more microorganisms than insects collected in the field (18). Assessing the role of microorganisms has the additional difficulty of the existence of several other possible mechanisms for CFHinduced ethylene synthesis, including mechanical damage, injection of hydrolytic enzymes, injection of elicitors, injection of IAA, or injection of ACC (14).Efforts to rear CFH devoid of microorganisms have been unsuccessful, but examination of excised CFH salivary glands revealed that those collected from certain host plants contained little or no microbial contamination (18). This observation offered a strategy to examine the role of the insect and associated microorganisms in the induction of stress ethylene synthesis in cotton. Surface-sterilized CFH with minimally contaminated salivary glands were employed along with cultures of three microorganisms. These microorganisms were identified in an extensive survey as the most common genera in the salivary glands of natural CFH populations (18). Additional objectives were to compare for the first time the effects of immature insects with those of the more mobile adult, to employ a cultivar of cotton which is highly susceptible to a disease caused by XCM, to compare ethylene production by the microorganisms in culture to that when inoculated into cotton shoot tips, and to test the possibility that the microorganisms possess nonenzymic elicitor activity. Stress-induced ethylene production has been implicated in cotton (Gossypium hirsutum L.) flower bud abscission caused by the cotton fleahopper, Pseudatomoscelis seriatus (Reuter). This insect feeds on the cotton shoot...

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“…A pesar de su importancia, poco se conoce acerca de los mecanismos de patogénesis de P. digitatum. La inoculación con este hongo afecta considerablemente el contenido en ácido galacturónico en la piel (Achilea et al, 1985a). Durante el proceso de infección, P. digitatum produce exo-poligalacturonasa que hidroliza la pectina de la pared celular formando monómeros de ácido galacturónico (Barmore y Brown, 1979).…”

Section: 1unclassified

“…Conforme avanza la infección, el incremento de su biomasa conlleva a que el hongo sea responsable de prácticamente la totalidad de la producción del ET en estadios más avanzados. (Achilea et al, 1985a;Achilea et al, 1985b). Posteriores estudios con otros hongos patógenos sobre frutos cítricos confirmaron este comportamiento.…”

Section: Respuestas De Los Frutos Cítricosunclassified

Cambios de expresión génica asociados a la respuesta de los frutos cítricos frente a la infección por hongos del género Penicillium.

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Ethylene biosynthesis and related physiological changes in Penicillium digitatum-infected grapefruit (Citrus paradisi)

Cited by 30 publications

References 25 publications

Resistance Responses of Potato to Vesicular-Arbuscular Mycorrhizal Fungi under Varying Abiotic Phosphorus Levels

Resistance Responses of Potato to Vesicular-Arbuscular Mycorrhizal Fungi under Varying Abiotic Phosphorus Levels

Cotton Fleahopper and Associated Microorganisms as Components in the Production of Stress Ethylene by Cotton

Cambios de expresión génica asociados a la respuesta de los frutos cítricos frente a la infección por hongos del género Penicillium.

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