<i>Rhodococcus fascians</i> in Herbaceous Perennials

Putnam, M. L.; Miller, Marilyn L.

doi:10.1094/pdis-91-9-1064

Cited by 68 publications

(54 citation statements)

References 70 publications

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“…Rhodococcus fascians is a gram-positive actinomycete that causes symptoms ranging from leaf deformation to differentiated shooty outgrowths known as leafy galls in more than 150 different plant species (Goethals et al, 2001;Stes et al, 2011). In ornamental plants, such infections reduce their value and contribute to economic losses worldwide (Putnam and Miller, 2007). Leafy gall symptoms are reminiscent of CK overproduction and can be partially induced by exogenous application of CKs (Thimann and Sachs, 1966;Eason et al, 1996).…”

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confidence: 99%

Methylated Cytokinins from the Phytopathogen Rhodococcus fascians Mimic Plant Hormone Activity

Venkatesan

Ueda²,

Tsuboi

et al. 2015

Plant Physiol.

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ORCID ID: 0000-0001-5449-6492 (H.S.).Cytokinins (CKs), a class of phytohormones that regulate plant growth and development, are also synthesized by some phytopathogens to disrupt the hormonal balance and to facilitate niche establishment in their hosts. Rhodococcus fascians harbors the fasciation (fas) locus, an operon encoding several genes homologous to CK biosynthesis and metabolism. This pathogen causes unique leafy gall symptoms reminiscent of CK overproduction; however, bacterial CKs have not been clearly correlated with the severe symptoms, and no virulence-associated unique CKs or analogs have been identified. Here, we report the identification of monomethylated MeCKs were recognized by a CK receptor and up-regulated type-A ARABIDOPSIS THALIANA RESPONSE REGULATOR genes. Treatment with MeCKs inhibited root growth, a hallmark of CK action, whereas the receptor mutant was insensitive. MeCKs were retained longer in planta than canonical CKs and were poor substrates for a CK oxidase/ dehydrogenase, suggesting enhanced biological stability. MeCKs were synthesized by S-adenosyl methionine-dependent methyltransferases (MT1 and MT2) that are present upstream of the fas genes. The best substrate for methylation was isopentenyl diphosphate. MT1 and MT2 catalyzed distinct methylation reactions; only the MT2 product was used by FAS4 to synthesize monomethylated N 6 -(Δ 2 -isopentenyl)adenine. The MT1 product was dimethylated by MT2 and used as a substrate by FAS4 to produce dimethylated N 6 -(Δ 2 -isopentenyl)adenine. Chemically synthesized MeCKs were comparable in activity. Our results strongly suggest that MeCKs function as CK mimics and play a role in this plant-pathogen interaction.

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confidence: 99%

Methylated Cytokinins from the Phytopathogen Rhodococcus fascians Mimic Plant Hormone Activity

Venkatesan

Ueda²,

Tsuboi

et al. 2015

Plant Physiol.

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“…However, in our study no symbiosis or nitrogen fixation related genes were detected for the isolates of this genus. Some genera including, Arthrobacter, Microbacterium, Rhodococcus, Sphingomonas, Bacillus, Cohnella, Pseudomonas and Herbaspirillum, were previously reported from root nodules of several legume species (Sturz et al, 1997;Mantelin et al, 2006;Zakhia et al, 2006;Putnam and Miller, 2007;Zurdo-Pineiro et al, 2007;Palaniappan et al, 2010). Other bacterial genera encountered, including Pantoea, Corynebacterium, Chryseobacterium, Sphingomonas and Xanthomonas, were described previously as endophytes in certain plant tissues including legume plant tissue (Burch and Sarathchandra, 2006).…”

Section: Discussionmentioning

confidence: 96%

A large diversity of non-rhizobial endophytes found in legume root nodules in Flanders (Belgium)

Meyer

Beuf

Vekeman

et al. 2015

Soil Biology and Biochemistry

111

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Statistical analysis grouped the investigated plant species into six clusters according to the presence of particular NRE. However, no correlations could be found within these six clusters towards plant tribes or ecoregions the plants had been sampled from. Cluster analysis of the ecoregions according to the presence of NRE, revealed correlations between bacterial genera and those areas. However, groups present in the ecoregions did not correlate with the groups present in the different plant clusters. When combining our previous study on rhizobial diversity recovered from the same sampling campaign (De Meyer et al., 2011) with the current study, 84.1% of the isolates belonged to the traditional rhizobia groups and only 15.9% were NRE. The Loamy ecoregion yielded the lowest number of culturable NRE (8.04%) and the Campine ecoregion the highest number (24.19%). The present study highlights the frequent presence of these NRE in root nodules. The occurrence of certain rhizobia was correlated with the presence of particular NRE, suggesting their presence may not be accidental, however their functions remain unclear at this point.

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“…The plant pathogenic actinomycete R. fascians is rather unique among the hyperplasia-inducing bacteria because it induces the formation of differentiated galls upon infection of its many hosts (Putnam and Miller, 2007). Typical symptoms observed in Arabidopsis are small serrated leaves, early flowering, inhibition of floral stalk elongation, activation of axillary meristems, de novo meristem formation in the axillary regions of the rosette, and delayed senescence.…”

Section: Discussionmentioning

confidence: 99%

An Integrated Genomics Approach to Define Niche Establishment byRhodococcus fascians

et al. 2008

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Rhodococcus fascians is a Gram-positive phytopathogen that induces shooty hyperplasia on its hosts through the secretion of cytokinins. Global transcriptomics using microarrays combined with profiling of primary metabolites on infected Arabidopsis (Arabidopsis thaliana) plants revealed that this actinomycete modulated pathways to convert its host into a niche. The transcript data demonstrated that R. fascians leaves a very characteristic mark on Arabidopsis with a pronounced cytokinin response illustrated by the activation of cytokinin perception, signal transduction, and homeostasis. The microarray data further suggested active suppression of an oxidative burst during the R. fascians pathology, and comparison with publicly available transcript data sets implied a central role for auxin in the prevention of plant defense activation. Gene Ontology categorization of the differentially expressed genes hinted at a significant impact of infection on the primary metabolism of the host, which was confirmed by subsequent metabolite profiling. The much higher levels of sugars and amino acids in infected plants are presumably accessed by the bacteria as carbon and nitrogen sources to support epiphytic and endophytic colonization. Hexoses, accumulating from a significantly increased invertase activity, possibly inhibited the expression of photosynthesis genes and photosynthetic activity in infected leaves. Altogether, these changes are indicative of sink development in symptomatic tissues. The metabolomics data furthermore point to the possible occurrence of secondary signaling during the interaction, which might contribute to symptom development. These data are placed in the context of regulation of bacterial virulence gene expression, suppression of defense, infection phenotype, and niche establishment.

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Rhodococcus fascians in Herbaceous Perennials

Cited by 68 publications

References 70 publications

Methylated Cytokinins from the Phytopathogen Rhodococcus fascians Mimic Plant Hormone Activity

Methylated Cytokinins from the Phytopathogen Rhodococcus fascians Mimic Plant Hormone Activity

A large diversity of non-rhizobial endophytes found in legume root nodules in Flanders (Belgium)

An Integrated Genomics Approach to Define Niche Establishment byRhodococcus fascians

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