Inhibition of Auxin Signaling in <i>Frankia</i> Species-Infected Cells in <i>Casuarina glauca</i> Nodules Leads to Increased Nodulation

Champion, Antony; Lucas, Mikaël; Tromas, Alexandre; Vaissayre, Virginie; Crabos, Amandine; Diédhiou, Issa; Prodjinoto, Hermann; Moukouanga, Daniel; Pirolles, Elodie; Cissoko, Maïmouna; Bonneau, Jocelyne; Gherbi, Hassen; Franche, Claudine; Hocher, Valérie; Svistoonoff, Sergio; Laplaze, Laurent

doi:10.1104/pp.114.255307

Cited by 21 publications

(9 citation statements)

References 51 publications

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“…As exogenous auxin partially restored the normal number of nodules in STTM160 roots, this mobile signal is likely to act downstream of auxin. In Casuarina glauca , auxin activity in Frankia ‐infected cells appears to limit the number of nodules (Champion et al ., ), suggesting that this may be an evolutionarily conserved mechanism.…”

Section: Discussionmentioning

confidence: 99%

microRNA160 dictates stage‐specific auxin and cytokinin sensitivities and directs soybean nodule development

et al. 2015

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SUMMARYLegume nodules result from coordinated interactions between the plant and nitrogen-fixing rhizobia. The phytohormone cytokinin promotes nodule formation, and recent findings suggest that the phytohormone auxin inhibits nodule formation. Here we show that microRNA160 (miR160) is a key signaling element that determines the auxin/cytokinin balance during nodule development in soybean (Glycine max). miR160 appears to promote auxin activity by suppressing the levels of the ARF10/16/17 family of repressor ARF transcription factors. Using quantitative PCR assays and a fluorescence miRNA sensor, we show that miR160 levels are relatively low early during nodule formation and high in mature nodules. We had previously shown that ectopic expression of miR160 in soybean roots led to a severe reduction in nodule formation, coupled with enhanced sensitivity to auxin and reduced sensitivity to cytokinin. Here we show that exogenous cytokinin restores nodule formation in miR160 over-expressing roots. Therefore, low miR160 levels early during nodule development favor cytokinin activity required for nodule formation. Suppression of miR160 levels using a short tandem target mimic (STTM160) resulted in reduced sensitivity to auxin and enhanced sensitivity to cytokinin. In contrast to miR160 over-expressing roots, STTM160 roots had increased nodule formation, but nodule maturation was significantly delayed. Exogenous auxin partially restored proper nodule formation and maturation in STTM160 roots, suggesting that high miR160 activity later during nodule development favors auxin activity and promotes nodule maturation. Therefore, miR160 dictates developmental stage-specific sensitivities to auxin and cytokinin to direct proper nodule formation and maturation in soybean.

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Section: Discussionmentioning

confidence: 99%

microRNA160 dictates stage‐specific auxin and cytokinin sensitivities and directs soybean nodule development

et al. 2015

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“…A local accumulation of auxins depending on the AUX1 influx carrier was linked to Frankia nitrogen-fixing bacterial infections in the Casuarina glauca actinorhizal host plant forming symbiotic nodules evolutionary related to the legume nodulation ( Péret et al, 2007 ; Perrine-Walker et al, 2010 ). Using a dominant-negative version of an auxin signaling repressor gene expressed in actinorhizal nodules, Indole-3-Acetic Acid7 (IAA7), to specifically inhibit auxin signaling in Frankia -infected cells, an increased actinorhizal nodulation was observed ( Champion et al, 2015 ). This suggests a model where auxins, notably produced by Frankia symbiotic bacteria, induce the degradation of IAA7 and thus activate auxin-signaling, ultimately leading to an inhibitory negative feedback on nodulation.…”

Section: Introductionmentioning

confidence: 99%

How Auxin and Cytokinin Phytohormones Modulate Root Microbe Interactions

2016

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A large range of microorganisms can associate with plants, resulting in neutral, friendly or hostile interactions. The ability of plants to recognize compatible and incompatible microorganisms and to limit or promote their colonization is therefore crucial for their survival. Elaborated communication networks determine the degree of association between the host plant and the invading microorganism. Central to these regulations of plant microbe interactions, phytohormones modulate microorganism plant associations and coordinate cellular and metabolic responses associated to the progression of microorganisms across different plant tissues. We review here hormonal regulations, focusing on auxin and cytokinin phytohormones, involved in the interactions between plant roots and soil microorganisms, including bacterial and fungi associations, either beneficial (symbiotic) or detrimental (pathogenic). The aim is to highlight similarities and differences in cytokinin/auxin functions amongst various compatible versus incompatible associations.

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“…The production of IAA has been widely studied in actinobacteria [47][48][49][50][51][52][53]. Authors like El-Shanshoury [47] suggest that IAA can act as endogen regulator of spore germination of Streptomyces atroolivacezlz and can be involved in the differentiation of actinobacteria [46].…”

Section: Indole Acetic Acid Productionmentioning

confidence: 99%

“…Streptomyces genus [47][48][49][50][51][52][53], Frankia sp. [47,51,54], Nocardia sp. [47,54], Kitasatospora sp.…”

Section: Indole Acetic Acid Productionmentioning

confidence: 99%

Actinobacteria as Plant Growth-Promoting Rhizobacteria

Franco-Correa¹,

Chavarro-Anzola²

2016

Actinobacteria - Basics and Biotechnological Applications

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Abstract"ctinobacteria commonly inhabit the rhizosphere, being an essential part of this environment due to their interactions with plants. Such interactions have made possible to characterize them as plant growth-promoting rhizobacteria PGPR . "s PGPR, they possess direct or indirect mechanisms that favor plant growth. "ctinobacteria improve the availability of nutrients and minerals, synthesized plant growth regulators, and specially, they are capable of inhibiting phytopathogens. Different activities that are performed by actinobacteria have been studied, such as phosphate solubilization, siderophores production, and nitrogen fixation. Furthermore, actinobacteria do not contaminate the environment instead, they help to maintain the biotic equilibrium of soil by cooperating with nutrients cycling. The aforementioned is directly related to the quality and productivity of crops. Moreover, different aspects of these microorganisms have been studied, such as production of metabolites that improve plant growth, resilience against unfavorable environmental conditions, and beneficial and synergic interactions with arbuscular mycorrhizal fungi. Taking into account the above-mentioned activities, actinobacteria can be considered as possible plant fertilizers.

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Inhibition of Auxin Signaling in Frankia Species-Infected Cells in Casuarina glauca Nodules Leads to Increased Nodulation

Cited by 21 publications

References 51 publications

microRNA160 dictates stage‐specific auxin and cytokinin sensitivities and directs soybean nodule development

microRNA160 dictates stage‐specific auxin and cytokinin sensitivities and directs soybean nodule development

How Auxin and Cytokinin Phytohormones Modulate Root Microbe Interactions

Actinobacteria as Plant Growth-Promoting Rhizobacteria

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