Genotypic Diversity and Host-Specificity of Frankia Bacteria Associated with Sympatric Populations of Alnus rubra and Alnus rhombifolia in Oregon

Balkan, Mehmet A.; Stewart, Nathan U.; Kauffman, Emily S.; Wolfe, Emily R.; Ballhorn, Daniel J.

doi:10.3955/046.093.0307

Cited by 5 publications

(3 citation statements)

References 42 publications

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“…and their mycorrhizal fungi (Molina, 1981), our finding that cultivable fungal endophyte communities also differ between host species is not surprising. Although we did not focus on Frankia in this study, the fact that bacterial endophyte communities did not differ by host aligns with findings by Balkan et al (2020) that A. rubra and A. rhombifolia lack strong host specificity regarding their Frankia mutualists, implicating potential general cross‐compatibility of bacterial symbionts within Alnus .…”

Section: Discussionsupporting

confidence: 85%

Root nodules of red alder (Alnus rubra) and Sitka alder (Alnus viridis ssp. sinuata) are inhabited by taxonomically diverse cultivable microbial endophytes

Dove,

Wolfe,

Stewart

et al. 2024

MicrobiologyOpen

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The root nodules of actinorhizal plants are home to nitrogen‐fixing bacterial symbionts, known as Frankia, along with a small percentage of other microorganisms. These include fungal endophytes and non‐Frankia bacteria. The taxonomic and functional diversity of the microbial consortia within these root nodules is not well understood. In this study, we surveyed and analyzed the cultivable, non‐Frankia fungal and bacterial endophytes of root nodules from red and Sitka alder trees that grow together. We examined their taxonomic diversity, co‐occurrence, differences between hosts, and potential functional roles. For the first time, we are reporting numerous fungal endophytes of alder root nodules. These include Sporothrix guttuliformis, Fontanospora sp., Cadophora melinii, an unclassified Cadophora, Ilyonectria destructans, an unclassified Gibberella, Nectria ramulariae, an unclassified Trichoderma, Mycosphaerella tassiana, an unclassified Talaromyces, Coniochaeta sp., and Sistotrema brinkmanii. We are also reporting several bacterial genera for the first time: Collimonas, Psychrobacillus, and Phyllobacterium. Additionally, we are reporting the genus Serratia for the second time, with the first report having been recently published in 2023. Pseudomonas was the most frequently isolated bacterial genus and was found to co‐inhabit individual nodules with both fungi and bacteria. We found that the communities of fungal endophytes differed by host species, while the communities of bacterial endophytes did not.

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Section: Discussionsupporting

confidence: 85%

Root nodules of red alder (Alnus rubra) and Sitka alder (Alnus viridis ssp. sinuata) are inhabited by taxonomically diverse cultivable microbial endophytes

Dove,

Wolfe,

Stewart

et al. 2024

MicrobiologyOpen

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“…Currently, studies on actinorhizal symbiosis have mainly focused on the morphological structure of nodules, isolated cultures of Frankia , and the diversity of microbial communities in root nodules. Some studies have suggested that nodules of actinorhizal plants contain more than one species of Frankia , and that Frankia diversity in nodules may be related to host plant species, the geographical environment, and soil texture, but not to the abundance of Frankia in the soil ( Tekaya et al., 2018 ; Balkan et al., 2020 ). In addition, some non- Frankia microbes such as Streptomyces, Nocardia, and Micromonospora in nodules, may assist nodulation and promote plant growth ( Trujillo et al., 2015 ; Alekhya and Gopalakrishnan, 2017 ; Ghodhbane-Gtari et al., 2019 ; Karthikeyan et al., 2022 ).…”

Section: Introductionmentioning

confidence: 99%

High Frankia abundance and low diversity of microbial community are associated with nodulation specificity and stability of sea buckthorn root nodule

Liu,

Ni,

Duan

et al. 2024

Front. Plant Sci.

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IntroductionActinorhizal symbioses are gaining attention due to the importance of symbiotic nitrogen fixation in sustainable agriculture. Sea buckthorn (Hippophae L.) is an important actinorhizal plant, yet research on the microbial community and nitrogen cycling in its nodules is limited. In addition, the influence of environmental differences on the microbial community of sea buckthorn nodules and whether there is a single nitrogen-fixing actinomycete species in the nodules are still unknown.MethodsWe investigated the diversity, community composition, network associations and nitrogen cycling pathways of the microbial communities in the root nodule (RN), nodule surface soil (NS), and bulk soil (BS) of Mongolian sea buckthorn distributed under three distinct ecological conditions in northern China using 16S rRNA gene and metagenomic sequencing. Combined with the data of environmental factors, the effects of environmental differences on different sample types were analyzed. ResultsThe results showed that plants exerted a clear selective filtering effect on microbiota, resulting in a significant reduction in microbial community diversity and network complexity from BS to NS to RN. Proteobacteria was the most abundant phylum in the microbiomes of BS and NS. While RN was primarily dominated by Actinobacteria, with Frankia sp. EAN1pec serving as the most dominant species. Correlation analysis indicated that the host determined the microbial community composition in RN, independent of the ecological and geographical environmental changes of the sea buckthorn plantations. Nitrogen cycle pathway analyses showed that RN microbial community primarily functions in nitrogen fixation, and Frankia sp. EAN1pec was a major contributor to nitrogen fixation genes in RN.DiscussionThis study provides valuable insights into the effects of eco-geographical environment on the microbial communities of sea buckthorn RN. These findings further prove that the nodulation specificity and stability of sea buckthorn root and Frankia sp. EAN1pec may be the result of their long-term co-evolution.

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“…are important in the dynamic succession and nutrient cycle of many ecosystems ( Roy et al, 2007 ; Kennedy et al, 2010 ). At present, research on alder symbiotic N fixation focuses mostly on the diversity of and symbiotic relationship with nitrogen-fixing bacteria in root nodules ( Balkan et al, 2020 ; Wolfe et al, 2022 ; Vemulapally et al, 2022a ), while research on the actinobacteria and Frankia found in the root nodules of varied ploidy Alnus spp. has fallen behind in terms of community composition, structural diversity, and N fixation capacity.…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of nitrogen content and its influence on actinorhizal nodule and rhizospheric microorganism diversity in three Alnus species

Yuan,

Chen,

Huang

et al. 2023

Front. Microbiol.

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Alnus spp. (alder) are typical nonleguminous nitrogen-fixing trees that have a symbiotic relationship with Frankia. To explore the differences in nitrogen-fixing microorganisms between three alders (A. cremastogyne, A. glutinosa, and A. formosana) with different chromosome ploidies, the community structure and compositional diversity of potential nitrogen-fixing microorganism in root nodules and rhizosphere soil were comparatively analyzed using 16S rRNA and nitrogenase (nifH) gene sequencing. The nitrogen contents in the root nodules and rhizosphere soil were also determined. The results showed that the contents of total nitrogen and nitrate nitrogen in the root nodules of the three alders are significantly higher than those in the rhizosphere soils, while the ammonium nitrogen content show the opposite trend. The family, genus, and species levels showed obviously differences between root nodules and rhizosphere soils, while there were no significant differences at the classification level between the three alders. At the phylum level, the dominant phyla from 16S rRNA and nifH gene data in the root nodules and rhizosphere soil of the three alders are phylum Actinomycetota and phylum Pseudomonadota, respectively. The LEfSe results showed that there are significant differences in the dominant groups in the root nodules and rhizosphere oil of the three alders. The relative abundances of dominant groups also showed obvious differences between the root nodules and rhizosphere soils of three alders. The relative abundances of Frankia and unclassified_Frankia in root nodules are obviously higher than those in rhizosphere soils, and their relative abundances in A. glutinosa root nodules are significantly higher than those in A. cremastogyne and A. formosana at the genus and species levels. The diversity of potential nitrogen-fixing microorganism from 16S rRNA and nifH gene data in the A. glutinosa root nodules and rhizosphere soils are all higher than those in A. cremastogyne and A. formosana. The results of functional prediction also showed that the OTUs for nitrogen fixation, nitrate respiration, and ureolysis in A. glutinosa root nodules are higher than those in the other two alders. Redundancy analysis revealed that the total nitrogen content mostly affects the Frankia community. Overall, there are significant differences in the community composition and structure of potential nitrogen-fixing microorganism in the root nodules and rhizosphere soils between the three alders. A. glutinosa showed a relatively stronger nitrogen fixation capacity than A. formosana and A. cremastogyne. The results help elucidates how the community structure and nitrogen-fixing ability of potential nitrogen-fixing microorganism differ between alder species and serve as a reference for applying Frankia to alder plantations.

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Genotypic Diversity and Host-Specificity of Frankia Bacteria Associated with Sympatric Populations of Alnus rubra and Alnus rhombifolia in Oregon

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 5 publications

References 42 publications

Root nodules of red alder (Alnus rubra) and Sitka alder (Alnus viridis ssp. sinuata) are inhabited by taxonomically diverse cultivable microbial endophytes

Root nodules of red alder (Alnus rubra) and Sitka alder (Alnus viridis ssp. sinuata) are inhabited by taxonomically diverse cultivable microbial endophytes

High Frankia abundance and low diversity of microbial community are associated with nodulation specificity and stability of sea buckthorn root nodule

Comparative analysis of nitrogen content and its influence on actinorhizal nodule and rhizospheric microorganism diversity in three Alnus species

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