Patterns of phenolic compounds in leafy galls of tobacco

Vereecke, Danny; Messens, Eric; Klarskov, Klaus; Bruyn, André De; Montagu, Marc Van; Goethals, Koen

doi:10.1007/s004250050076

Cited by 48 publications

(19 citation statements)

References 34 publications

(38 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Upon addition of NIP extracts, IAA secretion did not increase, suggesting that leafy-gall-specific compounds are responsible for the observed enhancement of IAA production. Previous studies have indeed shown that the composition of amino acids and phenolic compounds differs between R. fascians-infected plant tissues and uninfected plants (19,58). Our data and previous reports also indicate that bacterial gene expression and physiology are modified in the presence of LG extracts.…”

Section: Discussionsupporting

confidence: 86%

Biosynthesis of Auxin by the Gram-Positive PhytopathogenRhodococcus fasciansIs Controlled by Compounds Specific to Infected Plant Tissues

Vandeputte

Öden

Mol

et al. 2005

Appl Environ Microbiol

Self Cite

118

View full text Add to dashboard Cite

The role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. The phytopathogen Rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. Phenotypic analysis of a leafy gall suggests that auxin may play an important role in the development of the symptoms. We show here for the first time that R. fascians produces and secretes the auxin indole-3-acetic acid. Interestingly, whereas noninfected-tobacco extracts have no effect, indole-3-acetic acid synthesis is highly induced in the presence of infected-tobacco extracts when tryptophan is not limiting. Indole-3-acetic acid production by a plasmid-free strain shows that the biosynthetic genes are located on the bacterial chromosome, although plasmid-encoded genes contribute to the kinetics and regulation of indole-3-acetic acid biosynthesis. The indole-3-acetic acid intermediates present in bacterial cells and secreted into the growth media show that the main biosynthetic route used by R. fascians is the indole-3-pyruvic acid pathway with a possible rate-limiting role for indole-3-ethanol. The relationship between indole-3-acetic acid production and the symptoms induced by R. fascians is discussed.The phytopathogenic actinomycete Rhodococcus fascians induces the development of a wide range of malformations on its numerous monocotyledonous and dicotyledonous host plants: leaf deformation, growth inhibition, witches' brooms, fasciations, and leafy galls (reference 23 and references therein). The leafy-gall structure, considered an extreme form of apical dominance (59), is the most severe outcome of the R. fasciansplant interaction. Consisting of small misshapen leaves and numerous buds that are inhibited for further outgrowth, the leafy gall is believed to result from the alteration of the endogenous hormone balance of the host plant (23). Leafy-gall features, such as leaf wrinkling, shoot multiplication, and delayed senescence, are typical cytokinin effects. In this respect, R. fascians pathogenicity has been linked to a linear plasmid (pFiD188) that carries different virulence genes. On pFiD188 an isopentenyl transferase (ipt) homologue is located that is essential for symptom development and has been found in all virulent strains examined thus far (14,15,53). Moreover, it is known that R. fascians can produce at least 11 different cytokinins in vitro (2,18,24,28,48,51). In R. fascians, cytokinins probably originate from two sources, either release from tRNA (36, 38) and/or condensation of isopentenyl pyrophosphate and 5Ј-AMP (14). Nevertheless, hitherto no clear correlation between known cytokinins and symptom development could be established (16,18), suggesting that new cytokinin-like molecules could be involved in the formation of the leafy gall (23).Formation of a leafy gall cannot be attributed solely to the action of cytokinin. Some leafy-gall charac...

show abstract

Section: Discussionsupporting

confidence: 86%

Biosynthesis of Auxin by the Gram-Positive PhytopathogenRhodococcus fasciansIs Controlled by Compounds Specific to Infected Plant Tissues

Vandeputte

Öden

Mol

et al. 2005

Appl Environ Microbiol

Self Cite

118

View full text Add to dashboard Cite

show abstract

“…Thus, the activation of the KNOX pathway in response to R. fascians infection might contribute to the circumvention of plant defense and the formation of local lesions in the epidermis. Indeed, accumulation of defense-related secondary metabolites (Vereecke et al, 1997;Lin et al, 2003) or extensive cell wall thickenings (de O. Manes et al, 2001(de O. Manes et al, , 2004, typical signs of strong defense responses, have not been observed upon R. fascians infection.…”

Section: Discussionmentioning

confidence: 99%

Modulation of the Hormone Setting byRhodococcus fasciansResults in EctopicKNOXActivation in Arabidopsis

et al. 2008

Self Cite

View full text Add to dashboard Cite

The biotrophic actinomycete Rhodococcus fascians has a profound impact on plant development and a common aspect of the symptomatology is the deformation of infected leaves. In Arabidopsis (Arabidopsis thaliana), the serrated leaf margins formed upon infection resemble the leaf phenotype of transgenic plants with ectopic expression of KNOTTED-like homeobox (KNOX) genes. Through transcript profiling, we demonstrate that class-I KNOX genes are transcribed in symptomatic leaves. Functional analysis revealed that BREVIPEDICELLUS/KNOTTED-LIKE1 and mainly SHOOT MERISTEMLESS were essential for the observed leaf dissection. However, these results also positioned the KNOX genes downstream in the signaling cascade triggered by R. fascians infection. The much faster activation of ARABIDOPSIS RESPONSE REGULATOR5 and the establishment of homeostatic and feedback mechanisms to control cytokinin (CK) levels support the overrepresentation of this hormone in infected plants due to the secretion by the pathogen, thereby placing the CK response high up in the cascade. Hormone measurements show a net decrease of tested CKs, indicating either that secretion by the bacterium and degradation by the plant are in balance, or, as suggested by the strong reaction of 35S:CKX plants, that other CKs are at play. At early time points of the interaction, activation of gibberellin 2-oxidase presumably installs a local hormonal setting favorable for meristematic activity that provokes leaf serrations. The results are discussed in the context of symptom development, evasion of plant defense, and the establishment of a specific niche by R. fascians.

show abstract

“…It is commonly accepted that neoplastic tissues have biochemical and physiological characteristics different from those of host plant tissues (Vereecke et al 1997;Hartley 1998;Schö nrogge et al 2000;Konno et al 2003). However, no general theory on the exact nature of these changes had emerged based on investigations in all the major groups of gall-inducer Á/host plant combinations.…”

Section: Discussionmentioning

confidence: 99%

Arthropod-induced neoplastic formations on trees change photosynthetic pigment levels and oxidative enzyme activities

Gailīte

Andersone

Ievinsh

2005

Journal of Plant Interactions

View full text Add to dashboard Cite

In order to test the hypothesis that arthropod-induced neoplastic formations on trees affect biochemical characteristics of both the newly formed galls and host plant tissues, biochemical characteristics with a possible adaptive role were determined in nine gall-former Á/host tree combinations. Photosynthetic pigments, extractable protein content, and oxidative enzyme activities were determined in gall tissues, leaf tissues of galled leaves, and leaves on ungalled tree branches. Neoplastic tissues were characterized by a low content of photosynthetic pigments, decreased chlorophyll a /b ratio, lower extractable protein content, and decreased activities of peroxidase and polyphenol oxidase as compared with ungalled host leaf tissues. In galled leaves or in leaves adjacent to galls, increased level of peroxidase activity was found. In several gall-inducer Á/host plant combinations, galled host plant tissues contained increased activity of polyphenol oxidase as well. The presented data reflect long-term systemic effects of neoplastic formation on host tree physiology suggesting that gall inducers affect potential adaptive responses of host plants.

show abstract

Patterns of phenolic compounds in leafy galls of tobacco

Cited by 48 publications

References 34 publications

Biosynthesis of Auxin by the Gram-Positive PhytopathogenRhodococcus fasciansIs Controlled by Compounds Specific to Infected Plant Tissues

Biosynthesis of Auxin by the Gram-Positive PhytopathogenRhodococcus fasciansIs Controlled by Compounds Specific to Infected Plant Tissues

Modulation of the Hormone Setting byRhodococcus fasciansResults in EctopicKNOXActivation in Arabidopsis

Arthropod-induced neoplastic formations on trees change photosynthetic pigment levels and oxidative enzyme activities

Contact Info

Product

Resources

About