Relationships among pure cultured strains of <i>Frankia</i> based on host specificity

Baker, Dwight

doi:10.1111/j.1399-3054.1987.tb06139.x

Cited by 165 publications

(83 citation statements)

References 8 publications

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“…Among the isolated strains tested, strain Mg15 isolated from M. gale was found to group with Elaeagnaceae strains by PCR-RFLP but not with the complete rrs gene sequence. However, this strain is atypical, since no nodulation was obtained on its original host plant, M. gale, but was obtained on Elaeagnaceae species (3,31). Thus it can be concluded that even if Myrica is often considered a promiscuous actinorhizal genus, our results show that M. gale does not exhibit such promiscuity in its natural environment.…”

Section: Vol 67 2001mentioning

confidence: 48%

Diversity and Specificity of Frankia Strains in Nodules of Sympatric Myrica gale, Alnus incana , and Shepherdia canadensis Determined by rrs Gene Polymorphism

Huguet

Batzli

Zimpfer

et al. 2001

Appl Environ Microbiol

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The identity of Frankia strains from nodules of Myrica gale, Alnus incana subsp. rugosa, and Shepherdia canadensis was determined for a natural stand on a lake shore sand dune in Wisconsin, where the three actinorhizal plant species were growing in close proximity, and from two additional stands with M. gale as the sole actinorhizal component. Unisolated strains were compared by their 16S ribosomal DNA (rDNA) restriction patterns using a direct PCR amplification protocol on nodules. Phylogenetic relationships among nodular Frankia strains were analyzed by comparing complete 16S rDNA sequences of study and reference strains. Where the three actinorhizal species occurred together, each host species was nodulated by a different phylogenetic group of Frankia strains. M. gale strains from all three sites belonged to an Alnus-Casuarina group, closely related to Frankia alni representative strains, and were low in diversity for a host genus considered promiscuous with respect to Frankia microsymbiont genotype. Frankia strains from A. incana nodules were also within the Alnus-Casuarina cluster, distinct from Frankia strains of M. gale nodules at the mixed actinorhizal site but not from Frankia strains from two M. gale nodules at a second site in Wisconsin. Frankia strains from nodules of S. canadensis belonged to a divergent subset of a cluster of Elaeagnaceae-infective strains and exhibited a high degree of diversity. The three closely related local Frankia populations in Myrica nodules could be distinguished from one another using our approach. In addition to geographic separation and host selectivity for Frankia microsymbionts, edaphic factors such as soil moisture and organic matter content, which varied among locales, may account for differences in Frankia populations found in Myrica nodules.The nitrogen-fixing actinomycete Frankia establishes a symbiosis with actinorhizal plants, leading to root nodule formation. The host plants, distributed among eight different families and more than 200 species (9), typically colonize N-deficient and disturbed environments such as bogs, sandy coastal dunes, arctic tundra, mine spoils, and volcanic soils. Many actinorhizal species occur early after disturbances and are pioneer species.Among the actinorhizal genera, Myrica, belonging to the Myricaceae family, has the widest geographic distribution. This genus is divided into 35 species, with 28 reported to be actinorhizal (9). They are small trees or shrubs common to nearly all major landmasses and with species occurring from tropical to temperate areas. According to morphological features (17), fossil and pollen records (26, 39), and a recent molecular study based on the rbcL gene (35), the Myricaceae family is considered the most primitive actinorhizal family.Since the first confirmed isolation of the microsymbiont genus Frankia (11), a variety of methods have been used to obtain a coherent classification of the bacterial symbiont at the species level: soluble protein patterns (5, 6, 25), isoenzyme patterns (24), fatty acids (5...

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Section: Vol 67 2001mentioning

confidence: 48%

Diversity and Specificity of Frankia Strains in Nodules of Sympatric Myrica gale, Alnus incana , and Shepherdia canadensis Determined by rrs Gene Polymorphism

Huguet

Batzli

Zimpfer

et al. 2001

Appl Environ Microbiol

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“…Among actinorhizal plants, the family Myricaceae is a good experimental model to study the specificity of symbiotic interactions, as it includes species with either narrow or broad symbiont specificity. Most Myricaceae species are promiscuous (nonselective for Frankia strains), but Myrica gale exhibits a narrow symbiont specificity, being nodulated only by cluster 1a strains (5,27). In addition, M. gale has the novel trait of exuding droplets of secondary metabolites at the fruit surface, and the phenolic contents of these metabolites are significantly different from those of other broad symbiont specificity Myricaceae species (our unpublished data).…”

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confidence: 99%

Differential Effects of Rare Specific Flavonoids on Compatible and Incompatible Strains in the Myrica gale - Frankia Actinorhizal Symbiosis

Popovici

Comte

Bagnarol

et al. 2010

Appl Environ Microbiol

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Plant secondary metabolites, and specifically phenolics, play important roles when plants interact with their environment and can act as weapons or positive signals during biotic interactions. One such interaction, the establishment of mutualistic nitrogen-fixing symbioses, typically involves phenolic-based recognition mechanisms between host plants and bacterial symbionts during the early stages of interaction. While these mechanisms are well studied in the rhizobia-legume symbiosis, little is known about the role of plant phenolics in the symbiosis between actinorhizal plants and Frankia genus strains. In this study, the responsiveness of Frankia strains to plant phenolics was correlated with their symbiotic compatibility. We used Myrica gale, a host species with narrow symbiont specificity, and a set of compatible and noncompatible Frankia strains. M. gale fruit exudate phenolics were extracted, and 8 dominant molecules were purified and identified as flavonoids by high-resolution spectroscopic techniques. Total fruit exudates, along with two purified dihydrochalcone molecules, induced modifications of bacterial growth and nitrogen fixation according to the symbiotic specificity of strains, enhancing compatible strains and inhibiting incompatible ones. Candidate genes involved in these effects were identified by a global transcriptomic approach using ACN14a strain whole-genome microarrays. Fruit exudates induced differential expression of 22 genes involved mostly in oxidative stress response and drug resistance, along with the overexpression of a whiB transcriptional regulator. This work provides evidence for the involvement of plant secondary metabolites in determining symbiotic specificity and expands our understanding of the mechanisms, leading to the establishment of actinorhizal symbioses.Over the course of evolution, plants have developed many strategies to adapt to their environment and manage their biotic interactions. The production of secondary metabolites is an important tool in many of these strategies. In particular, secondary metabolites are involved in plant-microbe interactions both as weapons in plant defense mechanisms and as early signals in mutualistic as well as pathogenic relationships (22). For example, sesquiterpenes and flavonoids are involved in the early steps of arbuscular mycorrhizal symbiosis (1, 62). Similarly, in the early stages of the rhizobia-legume symbiosis, recognition of host flavonoids enhances rhizospheric competitiveness and root colonization and is the basic mechanism through which rhizobia induce the transcription of nod genes, leading to root hair deformation and nodulation in the plant tissues (13,49,55).Actinorhizal symbiosis is a less well-known nitrogen-fixing interaction, resulting from the association between the actinobacterium Frankia and plants belonging to eight dicotyledonous families collectively called "actinorhizal": Betulaceae, Myricaceae, Rosaceae, Datiscaceae, Elaeagnaceae, Coriariaceae, Casuarinaceae, and Rhamnaceae (8). Due to the nitrogen-fixing...

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“…Moreover, this grouping based on ARDRA is driven by host plant infectivity rather than host plant origin of isolation. Some Casuarina (NRRL-B16306 and NRRL-B16412) and Ceanothus (NRRL-B16316) strains that are non infective on the latter host plant but infective on Elaeagnus (Baker, 1987) (example Casuarina strains) indicate noteworthy genome variability among Frankia strains. While grouping is possible at high cutoff, the generated genogroups are not correlated to host infection groups that are determined in this study based on amplified ribosomal DNA restriction analysis.…”

Section: Resultsmentioning

confidence: 99%

Amplified ribosomal DNA restriction analysis and repetitive element polymorphism-polymerase chain reaction (rep-PCR) DNA fingerprinting of members of Frankia genus

Ghodhbane‐Gtari¹,

Boudabous²

2014

Afr. J. Microbiol. Res.

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Relationships among pure cultured strains of Frankia based on host specificity

Cited by 165 publications

References 8 publications

Diversity and Specificity of Frankia Strains in Nodules of Sympatric Myrica gale, Alnus incana , and Shepherdia canadensis Determined by rrs Gene Polymorphism

Diversity and Specificity of Frankia Strains in Nodules of Sympatric Myrica gale, Alnus incana , and Shepherdia canadensis Determined by rrs Gene Polymorphism

Differential Effects of Rare Specific Flavonoids on Compatible and Incompatible Strains in the Myrica gale - Frankia Actinorhizal Symbiosis

Amplified ribosomal DNA restriction analysis and repetitive element polymorphism-polymerase chain reaction (rep-PCR) DNA fingerprinting of members of Frankia genus

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