Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism

Wichner, Siegfried; Libbert, Eike

doi:10.1111/j.1399-3054.1968.tb07246.x

Cited by 41 publications

(10 citation statements)

References 35 publications

(2 reference statements)

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“…Crosstalk between auxin and plant defense responses has been known for many years. Most microbial pathogens possess the capacity to synthesize indole-3-acetic acid (IAA) (Fett et al, 1987;Wichner and Libbert, 1968). However, this capacity has been shown to be important for the pathogenicity of only a few pathogens such as P. syringae pv.…”

Section: Discussionmentioning

confidence: 99%

Overexpression of Arabidopsis MAP kinase kinase 7 leads to activation of plant basal and systemic acquired resistance

et al. 2007

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SummaryThere is a growing body of evidence indicating that mitogen-activated protein kinase (MAPK) cascades are involved in plant defense responses. Analysis of the completed Arabidopsis thaliana genome sequence has revealed the existence of 20 MAPKs, 10 MAPKKs and 60 MAPKKKs, implying a high level of complexity in MAPK signaling pathways, and making the assignment of gene functions difficult. The MAP kinase kinase 7 (MKK7) gene of Arabidopsis has previously been shown to negatively regulate polar auxin transport. Here we provide evidence that MKK7 positively regulates plant basal and systemic acquired resistance (SAR). The activationtagged bud1 mutant, in which the expression of MKK7 is increased, accumulates elevated levels of salicylic acid (SA), exhibits constitutive pathogenesis-related (PR) gene expression, and displays enhanced resistance to both Pseudomonas syringae pv. maculicola (Psm) ES4326 and Hyaloperonospora parasitica Noco2. Both PR gene expression and disease resistance of the bud1 plants depend on SA, and partially depend on NPR1. We demonstrate that the constitutive defense response in bud1 plants is a result of the increased expression of MKK7, and requires the kinase activity of the MKK7 protein. We found that expression of the MKK7 gene in wild-type plants is induced by pathogen infection. Reducing mRNA levels of MKK7 by antisense RNA expression not only compromises basal resistance, but also blocks the induction of SAR. Intriguingly, ectopic expression of MKK7 in local tissues induces PR gene expression and resistance to Psm ES4326 in systemic tissues, indicating that activation of MKK7 is sufficient for generating the mobile signal of SAR.

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Section: Discussionmentioning

confidence: 99%

Overexpression of Arabidopsis MAP kinase kinase 7 leads to activation of plant basal and systemic acquired resistance

et al. 2007

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“…IAA detection. -Tbe auxin contained in tbe ethereal solutions was checked by the Avena curvature test (daylight performance, Soding 1952, see Wichner andLibbert 1968 b). Mostly, tbe extracts were simultaneously separated by tbin layer cbromatograpby and tbe IAA traced by means of spray reagents (methods see Ballin 1964, also Wichner andLibbert 1968 b).…”

Section: Methodsmentioning

confidence: 99%

“…Both antibiotics (or their possible degradation products) did not disturb the Avena curvature test when used in the stated amounts (Wichner, unpublished). But they are able to suppress the IAA production from tryptophan by epiphytic bacteria Libbert 1968 a, 1968 b). 3.…”

Section: Auxin Gield Bg Long-duration Extraction Of Nonsterile Pea Epmentioning

confidence: 99%

“…Research work on the auxin content of liigher planls is usually done with nonslerile plant material. However, nonsterile plant parts are covered with epiphytic bacteria able to produce IAA from tryplophan (Libbert and Wichner 1963, Libbert et al 1966, Risch 1967, Wichner and Libbert 1968. Therefore the auxin amounts extractable from nonsterile plant material possibly partially originate from bacteria.…”

Section: Introductionmentioning

confidence: 99%

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Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metaholism

Wichner

1968

Physiologia Plantarum

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During an ether extraction (20 h, 4'^C), nonsterilc pea epicotyls dehver at lea.st 5 times more auxin than sterile ones. A great part of the additional auxin originates from a bacterial auxin production during the extraction. Presence of chloramphenicol or streptomycin during the extraction lowers the auxin amount extractable from nonsterile epicotyls. In extraction conditions (i.e. covered with ether, 20 h, 4 C), epiphytic bacteria contained in homogenates of nonsterile plant parts produce IAA from added tryptophan.Furthermore, first results are presented underlining the fact that epiphytic bacteria already produce auxin at the surface of nonsterile plant parts (before an extraction). Physiol. Plant., 21. lOOS [1356]

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“…The existence of BIPs was recognized very early in the research on auxin, and plant-associated BIPs have long been considered a source of contamination in measurements of IAA present in plant tissues (24,51,52). Later, BIPs were identified as the cause of symptoms associated with severe plant diseases such as gypsophila gall (26), knot disease of olive and oleander (43), and russet of pear fruit (25), or, in other cases, as benefactors of plants, e.g., nitrogen-fixing Bradyrhizobium japonicum in root nodules (9) and plant-growth-promoting rhizobacteria such as Pseudomonas putida (33).…”

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confidence: 99%

Utilization of the Plant Hormone Indole-3-Acetic Acid for Growth by Pseudomonas putida Strain 1290

Leveau

Lindow

2005

Appl Environ Microbiol

269

146

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We have isolated from plant surfaces several bacteria with the ability to catabolize indole-3-acetic acid (IAA). One of them, isolate 1290, was able to utilize IAA as a sole source of carbon, nitrogen, and energy. The strain was identified by its 16S rRNA sequence as Pseudomonas putida. Activity of the enzyme catechol 1,2-dioxygenase was induced during growth on IAA, suggesting that catechol is an intermediate of the IAA catabolic pathway. This was in agreement with the observation that the oxygen uptake by IAA-grown P. putida 1290 cells was elevated in response to the addition of catechol. The inability of a catR mutant of P. putida 1290 to grow at the expense of IAA also suggests a central role for catechol as an intermediate in IAA metabolism. Besides being able to destroy IAA, strain 1290 was also capable of producing IAA in media supplemented with tryptophan. In root elongation assays, P. putida strain 1290 completely abolished the inhibitory effect of exogenous IAA on the elongation of radish roots. In fact, coinoculation of roots with P. putida 1290 and 1 mM concentration of IAA had a positive effect on root development. In coinoculation experiments on radish roots, strain 1290 was only partially able to alleviate the inhibitory effect of bacteria that in culture overproduce IAA. Our findings imply a biological role for strain 1290 as a sink or recycler of IAA in its association with plants and plant-associated bacteria.One intriguing type of interorganismal interaction is the manipulation by some microbes of their host's hormone system. A good example is given by bacteria of the genus Wolbachia, which convert male woodlice into females, supposedly by suppressing a gland that produces a masculinizing hormone (37). Another striking example is the microbial production of plant hormones such as auxin, cytokinin, and gibberellin, which allows certain bacteria and fungi to direct a plant's physiology toward their own advantage (5,7,14,20).Indole-3-acetic acid (IAA) is the main auxin in plants, controlling many important physiological processes including cell enlargement and division, tissue differentiation, and responses to light and gravity (45). Bacterial IAA producers (BIPs) have the potential to interfere with any of these processes by input of IAA into the plant's auxin pool. The consequence for the plant is usually a function of (i) the amount of IAA that is produced and (ii) the sensitivity of the plant tissue to changes in IAA concentration. A root, for instance, is one of the plant's organs that is most sensitive to fluctuations in IAA, and its response to increasing amounts of exogenous IAA extends from elongation of the primary root, formation of lateral and adventitious roots, to growth cessation (8).The existence of BIPs was recognized very early in the research on auxin, and plant-associated BIPs have long been considered a source of contamination in measurements of IAA present in plant tissues (24, 51, 52). Later, BIPs were identified as the cause of symptoms associated with severe plant disease...

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Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism

Cited by 41 publications

References 35 publications

Overexpression of Arabidopsis MAP kinase kinase 7 leads to activation of plant basal and systemic acquired resistance

Overexpression of Arabidopsis MAP kinase kinase 7 leads to activation of plant basal and systemic acquired resistance

Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metaholism

Utilization of the Plant Hormone Indole-3-Acetic Acid for Growth by Pseudomonas putida Strain 1290

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