Frankia Populations in Soil and Root Nodules of Sympatrically Grown Alnus Taxa

• Published in: Microbial ecology Vol. 61; no. 1; pp. 92 - 100
• Main Authors: Pokharel, Anita, Mirza, Babur S, Dawson, Jeffrey O, Hahn, Dittmar
• Format: Journal Article
• Language: English
• Published: New York New York : Springer-Verlag 01-01-2011; Springer Science + Business Media; Springer-Verlag; Springer; Springer Nature B.V
• Subjects: Alluvial soils; Alnus; Alnus - microbiology; Alnus glutinosa; Alnus incana; Alnus japonica; Alnus maritima; Alnus rhombifolia; Alnus serrulata; Biological and medical sciences; Biomedical and Life Sciences; Clay loam soils; Ecology; Environmental conditions; Frankia; Frankia - classification; Frankia - genetics; Frankia - isolation & purification; Fundamental and applied biological sciences. Psychology; Genes, Bacterial - genetics; Genetic diversity; Genetic Variation; Geoecology/Natural Processes; Infections; Libraries; Life Sciences; Microbial Ecology; Microbiology; Molecular Sequence Data; Nature Conservation; Nodules; Oxidoreductases - genetics; Phylogeny; PLANT MICROBE INTERACTIONS; Plant Roots - microbiology; Plants; Population growth; Root nodules; Soil Microbiology; Soils; Taxa; Water Quality/Water Pollution; Comparative Sequence Analysis; nifH Gene; Frankia Strain; Root Nodule; Root Nodule Formation; Alnus; Sympatry; Frankiaceae; Ecology; Plant nodule; Woody plant; Frankia; Actinomycetales; Soils; Geographic distribution; Dicotyledones; Angiospermae; Bacteria; Actinomycetes; Spermatophyta; Betulaceae
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-010-9726-2

The genetic diversity of Frankia populations in soil and in root nodules of sympatrically grown Alnus taxa was evaluated by rep-polymerase chain reaction (PCR) and nifH gene sequence analyses. Rep-PCR analyses of uncultured Frankia populations in root nodules of 12 Alnus taxa (n = 10 nodules each) growing sympatrically in the Morton Arboretum near Chicago revealed identical patterns for nodules from each Alnus taxon, including replicate trees of the same host taxon, and low diversity overall with only three profiles retrieved. One profile was retrieved from all nodules of nine taxa (Alnus incana subsp. incana, Alnus japonica, Alnus glutinosa, Alnus incana subsp. tenuifolia, Alnus incana subsp. rugosa, Alnus rhombifolia, Alnus mandshurica, Alnus maritima, and Alnus serrulata), the second was found in all nodules of two plant taxa (A. incana subsp. hirsuta and A. glutinosa var. pyramidalis), and the third was unique for all Frankia populations in nodules of A. incana subsp. rugosa var. americana. Comparative sequence analyses of nifH gene fragments in nodules representing these three profiles assigned these frankiae to different subgroups within the Alnus host infection group. None of these sequences, however, represented frankiae detectable in soil as determined by sequence analysis of 73 clones from a Frankia-specific nifH gene clone library. Additional analyses of nodule populations from selected alders growing on different soils demonstrated the presence of different Frankia populations in nodules for each soil, with populations showing identical sequences in nodules from the same soil, but differences between plant taxa. These results suggest that soil environmental conditions and host plant genotype both have a role in the selection of Frankia strains by a host plant for root nodule formation, and that this selection is not merely a function of the abundance of a Frankia strain in soil.