Competition for Astragalus sinicus root nodule infection between its native microsymbiont Rhizobium huakuii bv. renge B3 and Rhizobium sp. ACMP18 strain, specific for Astragalus cicer

ABSTRACT Rhizobium sp. strain TAL1145 degrades the Leucaena toxin mimosine and its degradation product 3-hydroxy-4-pyridone (HP). The aim of this investigation is to characterize the Rhizobium genes for HP degradation and transport. These genes were localized by subcloning and mutagenesis on a previously isolated cosmid, pUHR263, containing mid genes of TAL1145 required for mimosine degradation. Two structural genes, pydA and pydB, encoding a metacleavage dioxygenase and a hydrolase, respectively, are required for degradation of HP, and three genes, pydC, pydD, and pydE, encoding proteins of an ABC transporter, are involved in the uptake of HP by TAL1145. These genes are induced by HP, although both pydA and pydB show low levels of expression without HP. pydA and pydB are cotranscribed, while pydC, pydD, and pydE are each transcribed from separate promoters. PydA and PydB show no homology with other dioxygenases and hydrolases in Sinorhizobium meliloti, Mesorhizobium loti, and Bradyrhizobium japonicum. Among various root nodule bacteria, the ability to degrade mimosine or HP is unique to some Leucaena-nodulating Rhizobium strains.

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Phylogeny and genetic diversity of the Astragalus cicer root nodule bacterial symbionts

Microbiology ◽

10.1134/s002626170701016x ◽

2007 ◽

Vol 76 (1) ◽

pp. 115-117

Author(s):

Al. Kh. Baimiev ◽

An. Kh. Baimiev ◽

I. I. Gubaidullin ◽

O. L. Kulikova ◽

A. V. Chemeris

Keyword(s):

Genetic Diversity ◽

Root Nodule ◽

Bacterial Symbionts ◽

Astragalus Cicer

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Biological Nitrogen Fixation and Root-Nodule Bacteria (Rhizobium Sp. and Bradyrhizobium Sp.) In Two Rehabilitating Sand Dune Areas Planted With Acacia Spp

Australian Journal of Botany ◽

10.1071/bt9850595 ◽

1985 ◽

Vol 33 (5) ◽

pp. 595 ◽

Cited By ~ 27

Author(s):

YM Barnet ◽

PC Catt ◽

DH Hearne

Keyword(s):

Nitrogen Fixation ◽

Biological Nitrogen Fixation ◽

Sand Dune ◽

Root Nodule ◽

Nodule Bacteria ◽

Root Nodule Bacteria ◽

Bradyrhizobium Sp ◽

Biological Nitrogen ◽

Slow Growing ◽

Rhizobium Sp

This paper reports a study of biological nitrogen fixation in two sand dune regions of New South Wales where planted Acacia spp. had been used in revegetation programmes. At one location (Bridge Hill Ridge), natural regrowth had produced a complex plant community, and native legumes in addition to the planted acacias were present. The other area (Wanda Beach) was a grossly disturbed site which contained only the planted species. Symbiotic fixation in association with Australian legumes occurred at both locations at rates within the range reported by other authors. Distinct seasonal changes were apparent, with higher activities in the cooler months. The legume association seemed the only source of biologically fixed nitrogen at Bridge Hill Ridge, but at Wanda Beach cyanobacteria in an algal mat also made a contribution. Fast and slow-growing bacterial strains were obtained from root nodules of native legumes at both sites and were classed as Rhizobium sp. and Bradyrhizobium sp., respectively. This division was supported by the pattern of serological affinities of the isolates and by differences in their protein profiles demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two atypical types of root-nodule bacteria were found at Bridge Hill Ridge: non-nodulating, fast-growing isolates and an abnormally slow-growing Bradyrhizobium sp.

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Sequence and Mutational Analysis of the 6.7-kb Region Containing nodAFEG Genes of Rhizobium sp. Strain N33: Evidence of DNA Rearrangements

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1997.10.3.401 ◽

1997 ◽

Vol 10 (3) ◽

pp. 401-406 ◽

Cited By ~ 11

Author(s):

Jean Cloutier ◽

Serge Laberge ◽

Hani Antoun

Keyword(s):

Wild Type Strain ◽

Mutational Analysis ◽

Open Reading Frames ◽

Wild Type ◽

Reading Frame ◽

Onobrychis Viciifolia ◽

Intergenic Regions ◽

Astragalus Cicer ◽

Reading Frames ◽

Rhizobium Sp

A 6.7-kb region upstream of nodBC genes in Rhizobium sp. strain N33 was shown to contain the nodAFEG genes and an open reading frame designated orfZ. The open reading frames for these genes contain 591, 282, 1209, 738, and 1,338 nucleotides respectively. Homologues of these genes were found in other rhizobia with the exception of orfZ, for which there was no counterpart found in the GenBank/EMBL database. Tn5 mutagenesis in nodEG and in the intergenic nodG-B region has shown a Nod+ phenotype on their temperate hosts Onobrychis viciifolia and Astragalus cicer. The nodules formed on O. viciifolia plants by these mutants were altered in shape and size. However, on A. cicer there was only a reduction in the number of nodules formed, compared with the wild-type strain. Sequence analysis of the orfZ-nodA and nodG-B intergenic regions indicates the presence of truncated nodD genes.

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