Bradyrhizobium spp. (TGx) isolates nodulating the new soybean cultivars in Africa are diverse and distinct from bradyrhizobia that nodulate North American soybeans
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Date
2000
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Academia
Abstract
The newly developed cultivars of soybean in Africa, known as Tropical Glycine
cross (TGx), are nodulated by bradyrhizobia indigenous to African soils, here
designated Bradyrhizobium spp. (TGx). Isolates of Bradyrhizobium spp. (TGx)
obtained from nodules of TGx soybeans that were inoculated with soils from
65 locations in six African countries were characterized and grouped into 11
phylogenetic clusters on the basis of RFLP of the 16S rRNA gene. Five
restriction enzymes (RsaI, HinfI, MspI, CfoI and HaeIII) established RFLP groups
within these Bradyrhizobium spp. (TGx) isolates, which were used to construct
a phylogenetic tree showing their genetic relationship with other
Bradyrhizobium species. RFLP analysis indicated that Bradyrhizobium spp.
(TGx) is a heterogeneous group with some isolates related to Bradyrhizobium
japonicum and Bradyrhizobium elkanii strains and some to Bradyrhizobium
spp. (misc.) reference strains isolated from a variety of tropical legumes. The
heterogeneity within the large phylogenetic clusters was further examined
through analysis of randomly amplified polymorphic DNA (RAPD) using GC rich PCR primers.
The RAPD analysis showed additional heterogeneity in the
Bradyrhizobium spp. (TGx) phylogenetic clusters, which was not revealed by
separations based on RFLP analysis. The Bradyrhizobium spp. (TGx) isolates
were classified into effective and ineffective types based on their symbiotic
performance on TGx soybean. The isolates were randomly distributed
throughout the phylogenetic clu
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This article is Published by Academia, 2000
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Citation
International Journal of Systematic and Evolutionary Microbiology (2000), 50, 225–234