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Diversity of frankia strains in root nodules of plants from the families elaeagnaceae and rhamnaceae

ABSTRACT: Partial 16S ribosomal DNAs (rDNAs) were PCR amplified and sequenced from Frankia strains living in root nodules of plants belonging to the families Elaeagnaceae and Rhamnaceae, including Colletia hystrix, Elaeagnus angustifolia, an unidentified Elaeagnus sp., Talguenea quinquenervia, and Trevoa trinervis. Nearly full-length 16S rDNAs were sequenced from strains of Frankia living in nodules of Ceanothus americanus, C. hystrix, Coriaria arborea, and Trevoa trinervis. Partial sequences also were obtained from Frankia strains isolated and cultured from the nodules of C. hystrix, Discaria serratifolia, D. trinervis, Retanilla ephedra, T. quinquenervia, and T. trinervis (Rhamnaceae). Comparison of these sequences and other published sequences of Frankia 16S rDNA reveals that the microsymbionts and isolated strains from the two plant families form a distinct phylogenetic clade, except for those from C. americanus. All sequences in the clade have a common 2-base deletion compared with other Frankia strains. Sequences from C. americanus nodules lack the deletion and cluster with Frankia strains infecting plants of the family Rosaceae. Published plant phylogenies (based on chloroplast rbcL sequences) group the members of the families Elaeagnaceae and Rhamnaceae together in the same clade. Thus, with the exception of C. americanus, actinorhizal plants of these families and their Frankia microsymbionts share a common symbiotic origin.

SUBMITTER: Clawson ML

PROVIDER: S-EPMC106764 | biostudies-literature | 1998 Sep

REPOSITORIES: biostudies-literature

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Diversity of frankia strains in root nodules of plants from the families elaeagnaceae and rhamnaceae

Clawson ML Caru M Benson DR

Applied and environmental microbiology 19980901 9

Partial 16S ribosomal DNAs (rDNAs) were PCR amplified and sequenced from Frankia strains living in root nodules of plants belonging to the families Elaeagnaceae and Rhamnaceae, including Colletia hystrix, Elaeagnus angustifolia, an unidentified Elaeagnus sp., Talguenea quinquenervia, and Trevoa trinervis. Nearly full-length 16S rDNAs were sequenced from strains of Frankia living in nodules of Ceanothus americanus, C. hystrix, Coriaria arborea, and Trevoa trinervis. Partial sequences also were ob ...[more]

PMID: 9726914

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Project description:Actinorhizal plants form nitrogen-fixing root nodules in symbiosis with soil-dwelling actinobacteria within the genus Frankia, and specific Frankia taxonomic clusters nodulate plants in corresponding host infection groups. In same-soil microcosms, we observed that some host species were nodulated (Alnus glutinosa, Alnus cordata, Shepherdia argentea, Casuarina equisetifolia) while others were not (Alnus viridis, Hippophaë rhamnoides). Nodule populations were represented by eight different sequences of nifH gene fragments. Two of these sequences characterized frankiae in S. argentea nodules, and three others characterized frankiae in A. glutinosa nodules. Frankiae in A. cordata nodules were represented by five sequences, one of which was also found in nodules from A. glutinosa and C. equisetifolia, while another was detected in nodules from A. glutinosa Quantitative PCR assays showed that vegetation generally increased the abundance of frankiae in soil, independently of the target gene (i.e., nifH or the 23S rRNA gene). Targeted Illumina sequencing of Frankia-specific nifH gene fragments detected 24 unique sequences from rhizosphere soils, 4 of which were also found in nodules, while the remaining 4 sequences in nodules were not found in soils. Seven of the 24 sequences from soils represented >90% of the reads obtained in most samples; the 2 most abundant sequences from soils were not found in root nodules, and only 2 of the sequences from soils were detected in nodules. These results demonstrate large differences between detectable Frankia populations in soil and those in root nodules, suggesting that root nodule formation is not a function of the abundance or relative diversity of specific Frankia populations in soils.IMPORTANCE The nitrogen-fixing actinobacterium Frankia forms root nodules on actinorhizal plants, with members of specific Frankia taxonomic clusters nodulating plants in corresponding host infection groups. We assessed Frankia diversity in root nodules of different host plant species, and we related specific populations to the abundance and relative distribution of indigenous frankiae in rhizosphere soils. Large differences were observed between detectable Frankia populations in soil and those in root nodules, suggesting that root nodule formation is not a function of the abundance or relative diversity of specific Frankia populations in soils but rather results from plants potentially selecting frankiae from the soil for root nodule formation. These data also highlight the necessity of using a combination of different assessment tools so as to adequately address methodological constraints that could produce contradictory data sets.

Dataset Information

Diversity of frankia strains in root nodules of plants from the families elaeagnaceae and rhamnaceae

Publications

Diversity of frankia strains in root nodules of plants from the families elaeagnaceae and rhamnaceae

Similar Datasets

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