Cytokinin-like activity in extracts from culture filtrates ofPseudomonas savastanoi

Surico, G.; Sparapano, Lorenzo; Lerario, P.; Durbin, R. D.; Iacobellis, Nicola Sante

doi:10.1007/bf02358857

Cited by 26 publications

(7 citation statements)

References 6 publications

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“…P. savastanoi secretes a number of cytokinins including the novel methylated derivative, 6-(4-hydroxy-1,3-dimethylbut-2-trans-enylamine-9-#;-D-ribofuranosyl)purine (ribosyl-l"-methylzeatin) (32,33). Although some strains of A. tumefaciens secrete zeatin (14), the situation is more complicated than in P. savastanoi.…”

mentioning

confidence: 98%

Secretion of Zeatin, Ribosylzeatin, and Ribosyl-1″ -Methylzeatin by Pseudomonas savastanoi

Macdonald¹,

Powell²,

Regier³

et al. 1986

Plant Physiol.

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Cytokinin production by strains of the phytopathogenic bacterium Pseudomonas syningae pv savastanoi was measured by immunoaffinity chromatography of the culture medium on immobilized anti-cytokinin antibodies, followed by high performance liquid chromatography, radioimmunoassay and mass spectrometry. P. sawastanoi strain PB213-2 secretes zeatin (80 nanograms per milliliter) and ribosylzeatin (80 nanograms per milliliter). Even higher levels of zeatin (400 nanograms per milliliter) are produced by the olive-specific strain EW1006, which also produces 180 nanograms per milliliter of the recently identified cytokinin, ribosyl-l"-methylzeatin. The amounts secreted were approximately 1000 times greater than those secreted by Agrobacterium tumefaciens Biochem Biophys Res Commun 104: 1560-1566. Examination of cytokinin production by' plasmid deletion mutants of PB213-2 and EW1006 indicated that cytokinin biosynthesis was specified, at least in part, by plasmid-borne genes. A fragment of the 105 kilobase pair plasmid from EW1006 was cloned into Escherichia coli where its expression resulted in dimethylallyl transferase activity and the secretion of zeatin.Gall-forming phytopathogenic bacteria have long been known to produce plant hormones (11,28) and there has been speculation, supported by recent evidence, that pathogenesis may be hormone-dependent. It is now known that the bacterial pathogens Pseudomonas syringae pv savastanoi and Agrobacterium tumefaciens contain genes which specify the synthesis of IAA. P. savastanoi, the causative organism of olive and oleander knot, contains two plasmid-born genes which specify IAA biosynthesis (6,7, 17); the first, iaaM, encodes the enzyme tryptophan monooxygenase (12) while the second, iaaH, encodes an indoleacetamide hydrolase. Both genes are required for effective

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mentioning

confidence: 98%

Secretion of Zeatin, Ribosylzeatin, and Ribosyl-1″ -Methylzeatin by Pseudomonas savastanoi

Macdonald¹,

Powell²,

Regier³

et al. 1986

Plant Physiol.

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“…These also occur in regular series along the branches at sites where leaf scars were infected. Development of knots is thought to be associated with production by the bacterium of auxin and cytokinins which would induce, in succession, hypertrophy, hyperplasia and vascular differentiation (37). Once the bacterium has died, growth of the knot stops, presumably because diffusion of these growth factors ceases.…”

Section: Electivity As a Specific Feature Of Plant Pathogensmentioning

confidence: 99%

Tissue and Organ Specificity in Plant Diseases

Graniti

1976

Specificity in Plant Diseases

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“…More recently, Southern blot hybridization experiments on various P. savastanoi strains from olive and whole genome sequencing of P. savastanoi strain NCPPB 3335 highlighted the existence of two copies of the IAA operon in each of these genomes, one of which at least in the case of NCPPB 3335, contains an iaaM pseudogene (Rodríguez‐Palenzuela et al ., ; Ramos et al ., ; Aragón et al ., ). It is also known that P. savastanoi from olive and oleander produce different cytokinins in vitro (Surico et al ., ; Surico & Iacobellis, ), including trans ‐zeatin ( t ‐Z), trans ‐zeatin riboside ( t ‐ZR), 1′‐methyl zeatin (1′‐MeZ) and 1″‐methyl zeatin riboside (1″‐MeZR); however, the pathway of cytokinin biosynthesis is much less defined compared to the metabolism of IAA. To date the only characterized determinant is the ptz gene, coding for an adenylate isopentenyl transferase (IPT) that is putatively responsible for the initial and rate‐limiting step of cytokinin biosynthesis (Powell & Morris, ; Ramos et al ., ; Caballo‐Ponce et al ., ).…”

Section: Introductionmentioning

confidence: 99%

The colonization processes of Myrtus communis by strains of Pseudomonas savastanoi with a differential ability to produce phytohormones

Schiff

Tani

Cimmino³

et al. 2019

Plant Pathology

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The ability to produce indole-3-acetic acid (IAA) through the indole-3-acetamide (IAM) pathway as well as cytokinins is a common trait of Pseudomonas savastanoi populations causing disease on oleander and olive. These phytohormones are required for the induction and development of an outgrowth of plant cell tissue termed a knot. However, in myrtle orchards of Sardinia (Italy), strains of P. savastanoi unable to produce cytokinins were found coexisting with cytokininproducing strains. Data presented here show that the ability to produce IAA through the IAM pathway is also a variable trait within this population, raising questions on the exact role of these plant growth substances in the disease process on myrtle. Three P. savastanoi strains were selected based on their differential ability to produce phytohormones in vitro, and their interaction with the host was investigated over a period of 8 months using histological methods. All strains successfully invaded the infected twigs, moving systemically (unhalted by host defences) upward and downward from the inoculation point, both by completely degrading the cell walls and by taking advantage of the xylem vessels and intercellular spaces. Moreover, all strains induced the development of cankers, which slowly evolved into typical knots only on the twigs inoculated with the phytohormone-producing strains. This study further demonstrates that cytokinins and IAA are essential for knot development; moreover, it ascertains that bacterial production of cytokinins is not necessary for host colonization and for the expression of pathogenicity (i.e. the ability to cause disease) of P. savastanoi on myrtle.

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Cytokinin-like activity in extracts from culture filtrates ofPseudomonas savastanoi

Cited by 26 publications

References 6 publications

Secretion of Zeatin, Ribosylzeatin, and Ribosyl-1″ -Methylzeatin by Pseudomonas savastanoi

Secretion of Zeatin, Ribosylzeatin, and Ribosyl-1″ -Methylzeatin by Pseudomonas savastanoi

Tissue and Organ Specificity in Plant Diseases

The colonization processes of Myrtus communis by strains of Pseudomonas savastanoi with a differential ability to produce phytohormones

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