Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism

Libbert, Eike; Risch, Hannelore

doi:10.1111/j.1399-3054.1969.tb07840.x

Cited by 64 publications

(19 citation statements)

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“…Another factor influencing the degradation and growth utilization of IAA is catabolite repression. Although the presence of fructose or glucose did not interfere with the ability of P. putida 1290 to degrade IAA, Libbert and Risch reported that degradation of IAA by their isolates was reduced in the presence of 0.2% glucose in phosphate buffer and even abolished with 5% glucose or 1% malic acid (23). In both the rhizosphere and on leaves, sugars such as glucose and fructose are abundantly available (16,21), suggesting that in such environments strains such as the ones described by Libbert and Rische would be less able to utilize available IAA and therefore would have a disadvantage over strains such as P. putida 1290.…”

Section: Discussionmentioning

confidence: 99%

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

Leveau

Lindow

2005

Appl Environ Microbiol

273

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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Section: Discussionmentioning

confidence: 99%

“…This is surprising given the early realization that, like BIPs, bacterial IAA degraders (BIDs) are abundantly associated with plants (1,2,23,29,38,49). Actually, BIDs were also considered a source of contamination, since their ability to destroy IAA obscured true levels of IAA in plant tissues (30,46).…”

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confidence: 92%

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

Leveau

Lindow

2005

Appl Environ Microbiol

273

146

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“…This hydroxylation has been described for the microorganism Pseudomonasfluorescens (21,28). It may, thus, be suspected that the indolyl-C, compounds observed in experiments with Orobanche are actually formed by contaminant bacteria (12). This suspicion is favored by the fact that, the epiphytic bacteria isolated from the plant material were flagellate and resistant to chloroamphenicol and, thus, may belong to the genus Pseudomonas.…”

Section: Methodsmentioning

confidence: 99%

Metabolism of Tryptophan, Indole-3-acetic Acid, and Related Compounds in Parasitic Plants from the Genus Orobanche

Magnus¹,

Šimaga²,

Iskrić³

et al. 1982

Plant Physiol.

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Metabolic reactions involving the aliphatic side chain of tryptophan were studied in the holoparasitic dicotyledonous plants Orobanche graciis Sm., 0. haea Baumg., and 0. ramosa L. Unlike known autotrophic plants, the parasite metabolized L-tryptophan directly to indole-3-carboxaldehyde, which was further converted to indole-3-methanol and indole-3-carboxylic acid. Independently, these metabolites were also formed from D-tryptophan, tryptamine, indole-3-lactic acid, and indole-3-acetic acid. As in autotrophic plants, tryptophan and tryptamine were also converted, via indole-3-acetaldehyde, to indole-3-acetic acid, indole-3-ethanol, and its glucoside. free from adhering soil and stored overnight. The plant material was cut into sections about 1 cm in length. Boiled plant material was prepared in flasks immersed in a boiling water bath for 30 min.Incubation Procedure. Substrate solutions (1 ml/g of plant material) were prepared in 0.067 M KH2PO4 (pH 4.5) at approximate concentrations of 1 mg/ml for D-and L-tryptophan, tryptamine hydrochloride, indole-3-lactic acid, and tryptophol, and 0.1 mg/ml for IAA, indole-3-acetaldehyde, indole-3-methanol, indole-3-carboxaldehyde, and indole-3-carboxylic acid. Inhibitors were added to the substrate solutions at 1 to 2 mg/ml for cycloserine and semicarbazide hydrochloride and 0.1 mg/ml for KCN. These solutions were vacuum-infiltrated (at 20 mm Hg) into the plant sections. The sections took up about one-quarter of the solutions, a great deal of which was retained in dead space, such as that in between bracts and in flower buds. Intemal substrate levels per g of metabolically active plant tissue are, thus, smaller than are those per ml of the external solutions by at least one order of magnitude. The plant material and the remaining substrate solutions were incubated separately at 22°C for 5 h, the latter with aeration.Prepurification of Plant Extracts. After incubation, the plant material was homogenized in a 2-fold (w/v) amount of methanol.The homogenate was filtered, and the residue was reextracted. The combined filtrates were stored at -10°C until used. They were then concentrated in vacuo to a few ml; methanol (50 ml) was added, and the mixture was left at -10°C overnight. The precipitate was discarded, and the filtrate was concentrated in vacuo, adjusted to 10 ml with methanol, and extracted, once with 30 ml and a second time with 15 ml of benzene. The combined extracts were evaporated and the residue extracted with 5 x

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“…Libbert and co-workers reported that such bacteria are responsible for the indoleacetic acid formed from tryptophan in incubation mixtures, including plant tissue from pea seedlings and a variety of other plant tissue (22,23). Large populations of Bacillus subtilis have been associated with phosphorus toxicity in soybeans (9).…”

Section: Discussionmentioning

confidence: 99%

Curtobacterium plantarum sp. nov. Is Ubiquitous in Plant Leaves and Is Seed Transmitted in Soybean and Corn

Dunleavy

1989

International Journal of Systematic Bacteriology

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A total of 22 strains of a yellow-pigmented bacterium which I designated YB, which were isolated from leaves of various plants, were compared with the type strains of Curtobacterium citreum, Curtobacterium albidum, Curtobacterium luteum, and Curtobacterium pusillum and six strains of Curtobacterium jlaccumfaciens, a pathogen of soybeans and garden beans. These species comprise the genus Curtobacterium. YB was nonpathogenic when it was inoculated onto leaves of soybeans and garden beans and produced p-carotene, as did both C. citreum and C . luteum. These species and YB were all originally isolated from plants. YB could be distinguished from all previously described species of the genus Curtobacterium on the basis of more rapid production of acid from maltose and xylose, more rapid hydrolysis of gelatin, susceptibility to bacteriophage PYB-3 infection, inability to hydrolyze hippurate, growth in the presence of 10% sodium chloride, and higher deoxyribonucleic acid guanine-plus-cytosine content. Because the YB strains represent a new center of variation in the genus Curtobacterium, a new species, Curtobacterium plantarum, is proposed. This bacterium was isolated from leaves of three soybean cultivars at weekly intervals. Mean populations, expressed in colony-forming units (CFU) per gram of leaf tissue, increased gradually over the season from 28 CFU/g at 5 weeks after planting to 158 CFU/g at plant maturity. The bacterium was also isolated from leaves of 10 soybean cultivars and 10 corn inbred lines in each of 3 years, from leaves in one soybean field and one corn field in each of 25 Iowa counties, and from leaves of each of 100 soybean plants from one field and 100 corn plants from one field. Over a 2-year period, it was isolated from all 200 plant species sampled. The samples represented 62 plant families and included trees (both broad leaved, and conifers), shrubs, annuals, and perennials. The bacterium was isolated from field-grown immature and mature soybean seeds and from leaves of soybean and corn seedlings grown in a microbe-free environment from seeds treated to eliminate external microorganisms. I concluded that C. plantarum sp. nov. is seed transmitted in soybeans and corn and is ubiquitous in the leaves of plants.From 1881, when T. J. Burrill first established that Erwinia amylovora (Burrill) Winslow, Broadhurst, Buchanan, Krumwiede, Rogers and Smith is the cause of fire blight of apples and pears, the following two groups of plant-associated bacteria have been recognized: the pathogens, which invade plant tissues and produce disease, and the saprophytes, which utilize leaf and root surfaces as substrates but cause no disease. While isolating Curtobacterium Jlaccumfaciens pv. Jaccumfaciens (Hedges) Collins and Jones, which is pathogenic for leaves of soybeans (GIycine max [L.] Merr.) and garden beans (Phaseolus vulgaris L.), I consistently observed colonies of another yellow-pigmented bacterium that I designated YB (yellow-pigmented bacterium). YB was associated with other plants, such as corn, oats, a...

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Interactions between Plants and Epiphytic Bacteria Regarding Their Auxin Metabolism

Cited by 64 publications

References 7 publications

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

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

Metabolism of Tryptophan, Indole-3-acetic Acid, and Related Compounds in Parasitic Plants from the Genus Orobanche

Curtobacterium plantarum sp. nov. Is Ubiquitous in Plant Leaves and Is Seed Transmitted in Soybean and Corn

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