Diversity among Bradyrhizobium isolates nodulating yardlong bean and sunnhemp in Guam.
OBJECTIVE
To isolate and characterize bradyrhizobia that nodulate yardlong bean and sunnhemp in Guam.


RESULTS
Bradyrhizobia populations that nodulate yardlong bean and sunnhemp in Guam were examined for genetic diversity and their relatedness to Bradyrhizobium japonicum and B. elkanii reference strains. Genomic DNA of 58 isolates of Bradyrhizobium spp. was hybridized with B. japonicum nodY and B. elkanii nodK genes. Based on the hybridization patterns, the isolates were classified into three nodY-nodK hybridizing groups. Group I comprised the majority of the isolates and hybridized with nodY whereas group II isolates hybridized with nodK. The group III isolates, that did not hybridize with either nodY or nodK, formed nitrogen-fixing nodules on cowpea but did not nodulate soybean. DNA sequence analysis of a 280-bp fragment of the variable region of the 16S rRNA gene of a few group III isolates showed that these isolates were more similar to Bradyrhizobium spp. than to B. japonicum or B. elkanii.


CONCLUSIONS
The majority of the isolates nodulating yardlong bean and sunnhemp in Guam are similar to B. japonicum, although some isolates are similar to Bradyrhizobium spp. that nodulate a miscellaneous group of legumes including cowpea.


CONCLUSIONS
Since both yardlong bean and sunnhemp are nodulated by a range of bradyrhizobia, selection of superior strains may be based on nodulation effectiveness on both legumes.
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Department of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI 96822, USA.
Marutani
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Borthakur
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D001426:Bacterial Proteins / Q000235:genetics; D020369:Bradyrhizobium / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000032:analysis; D007887:Fabaceae / Q000382:microbiology*; D020459:Genes, rRNA; D014644:Genetic Variation; D006141:Guam; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
D001426:Bacterial Proteins; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S