Plant-Associated Rhodococcus Species, for Better and for Worse

Francis, Isolde M.; Vereecke, Danny

doi:10.1007/978-3-030-11461-9_13

Cited by 9 publications

(13 citation statements)

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“…All these cytokinins could derive from tRNA (Murai et al, 1980; Pertry et al, 2010; Francis et al, 2016). Based on the above cluster analyses (Figures 1, 6) we suggest that the “Trick-with-the-Cytokinin-Mix” hypothesis of Pertry et al (2010) does not hold in terms of generality to plants considered host species for R. fascians , as foreshadowed in Francis and Vereecke (2019) who recently stated “time will tell if the fas operon and the Trick-with-the-Cytokinin-Mix are indeed determinative for leafy gall formation.”…”

Section: Discussionmentioning

confidence: 78%

The Cytokinin Complex Associated With Rhodococcus fascians: Which Compounds Are Critical for Virulence?

et al. 2019

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Virulent strains of Rhodococcus fascians cause a range of disease symptoms, many of which can be mimicked by application of cytokinin. Both virulent and avirulent strains produce a complex of cytokinins, most of which can be derived from tRNA degradation. To test the three current hypotheses regarding the involvement of cytokinins as virulence determinants, we used PCR to detect specific genes, previously associated with a linear virulence plasmid, including two methyl transferase genes ( mt1 and mt2 ) and fas4 (dimethyl transferase), of multiple strains of R. fascians . We inoculated Pisum sativum (pea) seeds with virulent and avirulent strains of R. fascians , monitored the plants over time and compared these to mock-inoculated controls. We used RT-qPCR to monitor the expression of mt1, mt2 , and fas4 in inoculated tissues and LC-MS/MS to obtain a comprehensive picture of the cytokinin complement of inoculated cotyledons, roots and shoots over time. The presence and expression of mt1 and mt2 was associated with those strains of R. fascians classed as virulent, and not those classed as avirulent. Expression of mt1, mt2 , and fas4 peaked at 9 days post-inoculation (dpi) in cotyledons and at 15 dpi in shoots and roots developed from seeds inoculated with virulent strain 602. Pea plants inoculated with virulent and avirulent strains of R. fascians both contained cytokinins likely to have been derived from tRNA turnover including the 2-methylthio cytokinins and cis -zeatin-derivatives. Along with the isopentenyladenine-type cytokinins, the levels of these compounds did not correlate with virulence. Only the novel 1- and 2-methylated isopentenyladenine cytokinins were uniquely associated with infection by the virulent strains and are, therefore, the likely causative factors of the disease symptoms.

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Section: Discussionmentioning

confidence: 78%

The Cytokinin Complex Associated With Rhodococcus fascians: Which Compounds Are Critical for Virulence?

et al. 2019

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“…Despite the absolute requirement of the linear plasmid for virulence in most leafy gall inducers, an important contribution of co-option of chromosomal and plasmid-encoded functions seems to guarantee a successful interaction with plants (Creason et al, 2014;Francis et al, 2016). As a result of metagenomic studies in search of biostimulants, it has now become evident that diverse Rhodococcus species are established members of the plant microbiome (Francis and Vereecke, 2019). Additionally, a novel disease on "UCB-1" pistachio rootstock trees, designated Pistachio Bushy Top Syndrome (PBTS) has been associated with the presence of two Rhodococcus species that act synergistically on their host (Stamler et al, 2015a,b).…”

Section: Introductionmentioning

confidence: 99%

Functional Genomics Insights Into the Pathogenicity, Habitat Fitness, and Mechanisms Modifying Plant Development of Rhodococcus sp. PBTS1 and PBTS2

et al. 2020

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Pistachio Bushy Top Syndrome (PBTS) is a recently emerged disease that has strongly impacted the pistachio industry in California, Arizona, and New Mexico. The disease is caused by two bacteria, designated PBTS1 that is related to Rhodococcus corynebacterioides and PBTS2 that belongs to the species R. fascians. Here, we assessed the pathogenic character of the causative agents and examined their chromosomal sequences to predict the presence of particular functions that might contribute to the observed co-occurrence and their effect on plant hosts. In diverse assays, we confirmed the pathogenicity of the strains on "UCB-1" pistachio rootstock and showed that they can also impact the development of tobacco species, but concurrently inconsistencies in the ability to induce symptoms were revealed. We additionally evidence that fas genes are present only in a subpopulation of pure PBTS1 and PBTS2 cultures after growth on synthetic media, that these genes are easily lost upon cultivation in rich media, and that they are enriched for in an in planta environment. Analysis of the chromosomal sequences indicated that PBTS1 and PBTS2 might have complementary activities that would support niche partitioning. Growth experiments showed that the nutrient utilization pattern of both PBTS bacteria was not identical, thus avoiding co-inhabitant competition. PBTS2 appeared to have the potential to positively affect the habitat fitness of PBTS1 by improving its resistance against increased concentrations of copper and penicillins. Finally, mining the chromosomes of PBTS1 and PBTS2 suggested that the bacteria could produce cytokinins, auxins, and plant growth-stimulating volatiles and that PBTS2 might interfere with ethylene levels, in support of their impact on plant development. Subsequent experimentation supported these in silico predictions. Altogether, our data provide an explanation for the observed pathogenic behavior and unveil part of the strategies used by PBTS1 and PBTS2 to interact with plants.

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“…Might the growth‐promoting skills of harmful gall‐inducers be put to a better purpose? Plasmid‐free R. fascians derivatives and other Rhodococcus species now are being explored for their potential to promote multi‐directional balanced plant growth (Francis et al , ; Savory et al , ; Francis & Vereecke, ). A different way to exploit parasitic gall‐inducers is to use knowledge about their plant interactions to discover plant features that we might target in order to increase crop yields.…”

Section: Galls As Parasitismmentioning

confidence: 99%

Plants make galls to accommodate foreigners: some are friends, most are foes

Harris

Pitzschke

2020

New Phytologist

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At the colonization site of a foreign entity, plant cells alter their trajectory of growth and development. The resulting structurea plant gallaccommodates various needs of the foreigner, which are phylogenetically diverse: viruses, bacteria, protozoa, oomycetes, true fungi, parasitic plants, and many types of animals, including rotifers, nematodes, insects, and mites. The plant species that make galls also are diverse. We assume gall production costs the plant. All is well if the foreigner provides a gift that makes up for the cost. Nitrogen-fixing nodule-inducing bacteria provide nutritional services. Gall wasps pollinate fig trees. Unfortunately for plants, most galls are made for foes, some of which are deeply studied pathogens and pests: Agrobacterium tumefaciens, Rhodococcus fascians, Xanthomonas citri, Pseudomonas savastanoi, Pantoea agglomerans, 'Candidatus' phytoplasma, rust fungi, Ustilago smuts, root knot and cyst nematodes, and gall midges. Galls are an understudied phenomenon in plant developmental biology. We propose gall inception for discovering unifying features of the galls that plants make for friends and foes, talk about molecules that plants and gall-inducers use to get what they want from each other, raise the question of whether plants colonized by arbuscular mycorrhizal fungi respond in a gall-like manner, and present a research agenda.'Only connect!' E. M. Forster, Howard's End

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Plant-Associated Rhodococcus Species, for Better and for Worse

Cited by 9 publications

References 91 publications

The Cytokinin Complex Associated With Rhodococcus fascians: Which Compounds Are Critical for Virulence?

The Cytokinin Complex Associated With Rhodococcus fascians: Which Compounds Are Critical for Virulence?

Functional Genomics Insights Into the Pathogenicity, Habitat Fitness, and Mechanisms Modifying Plant Development of Rhodococcus sp. PBTS1 and PBTS2

Plants make galls to accommodate foreigners: some are friends, most are foes

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