The genes involved in cytokinin biosynthesis in Erwinia herbicola pv. gypsophilae: characterization and role in gall formation

Lichter, Amnon; Barash, Isaac; Valinsky, Lea; Manulis, Shulamit

doi:10.1128/jb.177.15.4457-4465.1995

Cited by 97 publications

(41 citation statements)

References 29 publications

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“…Overproduction of cytokinins by the transduced IPT causes abnormal cell proliferation. The gene has been identified in various bacterial species (13)(14)(15)(16)(17), and the translated product has been proved to biosynthesize iPMP, an active cytokinin, in vitro (18). On the other hand, there is little concrete evidence of the authentic biosynthesis of iPMP by IPT in higher plants.…”

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confidence: 99%

Identification of Genes Encoding Adenylate Isopentenyltransferase, a Cytokinin Biosynthesis Enzyme, inArabidopsis thaliana

Takei¹,

Sakakibara

Sugiyama³

2001

Journal of Biological Chemistry

450

319

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The initial step in the de novo biosynthesis of cytokinin in higher plants is the formation of isopentenyladenosine 5-monophosphate (iPMP) from AMP and dimethylallylpyrophosphate (DMAPP), which is catalyzed by adenylate isopentenyltransferase (IPT). Although cytokinin is an essential hormone for growth and development, the nature of the enzyme for its biosynthesis in higher plants has not been identified. Herein, we describe the molecular cloning and biochemical identification of IPTs from Arabidopsis thaliana. Eight cDNAs encoding putative IPT, designated as AtIPT1 to AtIPT8, were picked up from A. thaliana. The Escherichia coli transformants expressing the recombinant proteins excreted cytokinin species into the culture medium except for that expressing AtIPT2 that is a putative tRNA IPT. A purified recombinant AtIPT1 catalyzed the formation of iPMP from DMAPP and AMP. These results indicate that the small multigene family contains both types of isopentenyltransferase, which could synthesize cytokinin and mature tRNA.

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confidence: 99%

Identification of Genes Encoding Adenylate Isopentenyltransferase, a Cytokinin Biosynthesis Enzyme, inArabidopsis thaliana

Takei¹,

Sakakibara

Sugiyama³

2001

Journal of Biological Chemistry

450

319

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“…A more subtle approach consists of disrupting the plant's hormone balance, resulting in the formation of hyperplasia without killing the host (such as crown galls by Agrobacterium tumefaciens [26] and galls by Pantoea agglomerans pv. gypsophilae [30] and Pseudomonas savastanoi pv. savastanoi [58]).…”

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confidence: 99%

Chromosomal Locus That Affects Pathogenicity ofRhodococcus fascians

et al. 2002

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The gram-positive plant pathogen Rhodococcus fascians provokes leafy gall formation on a wide range of plants through secretion of signal molecules that interfere with the hormone balance of the host. Crucial virulence genes are located on a linear plasmid, and their expression is tightly controlled. A mutant with a mutation in a chromosomal locus that affected virulence was isolated. The mutation was located in gene vicA, which encodes a malate synthase and is functional in the glyoxylate shunt of the Krebs cycle. VicA is required for efficient in planta growth in symptomatic, but not in normal, plant tissue, indicating that the metabolic requirement of the bacteria or the nutritional environment in plants or both change during the interaction. We propose that induced hyperplasia on plants represents specific niches for the causative organisms as a result of physiological alterations in the symptomatic tissue. Hence, such interaction could be referred to as metabolic habitat modification.The outcome of a plant-pathogen interaction results from the complex action of a whole set of genes, from both host and pathogen. The tools used by pathogens to provoke plant diseases are often well characterized, and a wide array of pathogenic approaches has been described, ranging from destructive to subtle strategies. The most destructive interactions are often lethal for the plant and result from the bacterial secretion of extracellular cell wall-degrading enzymes that literally digest the plant (for instance, soft rots by Pantoea species [1]) or from the obstruction of transport tissues leading to wilting (such as for Ralstonia solanacearum [23], Pantoea stewartii [28], and Corynebacterium species [29,46]). A more subtle approach consists of disrupting the plant's hormone balance, resulting in the formation of hyperplasia without killing the host (such as crown galls by Agrobacterium tumefaciens [26] and galls by Pantoea agglomerans pv. gypsophilae [30] and Pseudomonas savastanoi pv. savastanoi [58]).The most obvious reason why bacteria seek interaction with plants is nutrition. For the necrogenic pathogens, this nutritional benefit is clear. On the other hand, A. tumefaciens transfers a discrete piece of its tumor-inducing (Ti) plasmid, the T-DNA, which carries genes responsible for hormone and opine synthesis, to the plant nucleus (47). Opines are novel compounds whose structure depends on the bacterial strain that induces the crown gall. Only this strain carries the catabolic genes specific for that type of opine on its Ti plasmid (14). Hence, the bacterium that invests its energy into genetically transforming its host is rewarded in terms of specific nutritional compounds. However, for other hyperplasia-inducing bacteria such a benefit is not evident.Rhodococcus fascians (20) belongs to the latter class of pathogens. It is a gram-positive actinomycete with a very broad host range, encompassing both monocots and dicots (3, 53). It is a well-adapted epiphyte and grows on the surface of the plant as well as inside tissues...

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“…Pathogenicity tests were carried out on fresh cuttings of Gypsophila paniculata 'Perfecta' (Danziger Ltd, Bet Dagan, Israel), essentially according to Lichter et al (1995). After removal of a 2-3 mm section from the bottom of the stem, the cuttings were inoculated by dipping into a bacterial suspension of 10 9 cells ml 21 , placed in a vermiculitefilled tray and maintained at 25-28 uC.…”

Section: Methodsmentioning

confidence: 99%

Characterization of nuclear localization signals in the type III effectors HsvG and HsvB of the gall-forming bacterium Pantoea agglomerans

et al. 2011

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HsvG and HsvB, two paralogous type III effectors of the gall-forming bacteria Pantoea agglomerans pv. gypsophilae and P. agglomerans pv. betae, determine host specificity on gypsophila and beet, respectively. They were previously shown to be DNA-binding proteins imported into host and non-host nuclei and might act as transcriptional activators. Sequence analysis of these effectors did not detect canonical nuclear localization signals (NLSs), but two basic amino acid clusters designated putative NLS1 and NLS2 were detected in their N-terminal and C-terminal regions, respectively. pNIA assay for nuclear import in yeast and bombardment of melon leaves with each of the NLSs fused to a 2xYFP reporter indicated that putative NLS1 and NLS2 were functional in transport of HsvG into the nucleus. A yeast two-hybrid assay showed that HsvB, HsvG, putative NLS1, putative NLS2, HsvG converted into HsvB, or HsvB converted into HsvG by exchanging the repeat domain, all interacted with AtKAP-a and importin-a3 of Arabidopsis thaliana. Deletion analysis of the NLS domains in HsvG suggested that putative NLS1 or NLS2 were required for pathogenicity on gypsophila cuttings and presumably for import of HsvG into the nucleus. This study demonstrates the presence of two functional NLSs in the type III effectors HsvG and HsvB.

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The genes involved in cytokinin biosynthesis in Erwinia herbicola pv. gypsophilae: characterization and role in gall formation

Cited by 97 publications

References 29 publications

Identification of Genes Encoding Adenylate Isopentenyltransferase, a Cytokinin Biosynthesis Enzyme, inArabidopsis thaliana

Identification of Genes Encoding Adenylate Isopentenyltransferase, a Cytokinin Biosynthesis Enzyme, inArabidopsis thaliana

Chromosomal Locus That Affects Pathogenicity ofRhodococcus fascians

Characterization of nuclear localization signals in the type III effectors HsvG and HsvB of the gall-forming bacterium Pantoea agglomerans

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