Abstract
The induction of root nodules by the majority of rhizobia has a strict requirement for the secretion of symbiosis-specific lipochitooligosaccharides (nodulation factors [NFs]). The nature of the chemical substitution on the NFs depends on the particular rhizobium and contributes to the host specificity imparted by the NFs. We present here a description of the genetic organization of the nod gene cluster and the characterization of the chemical structure of the NFs associated with the broad-host-range Rhizobium sp. strain LPU83, a bacterium capable of nodulating at least alfalfa, bean, and Leucena leucocephala. The nod gene cluster was located on the plasmid pLPU83b. The organization of the cluster showed synteny with those of the alfalfa-nodulating rhizobia, Sinorhizobium meliloti and Sinorhizobium medicae. Interestingly, the strongest sequence similarity observed was between the partial nod sequences of Rhizobium mongolense USDA 1844 and the corresponding LPU83 nod genes sequences. The phylogenetic analysis of the intergenic region nodEG positions strain LPU83 and the type strain R. mongolense 1844 in the same branch, which indicates that Rhizobium sp. strain LPU83 might represent an early alfalfa-nodulating genotype. The NF chemical structures obtained for the wild-type strain consist of a trimeric, tetrameric, and pentameric chitin backbone that shares some substitutions with both alfalfa- and bean-nodulating rhizobia. Remarkably, while in strain LPU83 most of the NFs were sulfated in their reducing terminal residue, none of the NFs isolated from the nodH mutant LPU83-H were sulfated. The evidence obtained supports the notion that the sulfate decoration of NFs in LPU83 is not necessary for alfalfa nodulation.
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Claims 10
Claim · model-written summary
LPU83 nodulates alfalfa, bean, and Leucena leucocephala.
- Taxon
- alfalfa
Medicago sativae0 - Interactor
- a bacteriume0symbiont
- Outcome
- nodulatinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a bacterium capable of nodulating at least alfalfa, bean, and Leucena leucocephala”
Claim · model-written summary
The LPU83 nod gene cluster is on plasmid pLPU83b.
- Taxon
- AlfalfaMedicago sativat0
- Interactor
- Rhizobium sp. strain LPU83
Rhizobium sp.e1symbiont - Gene
- nod gene clustere0
- Outcome
- located on the plasmid pLPU83be0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The nod gene cluster was located on the plasmid pLPU83b.”
t0“Alfalfa”
e1“Rhizobium sp. strain LPU83 might represent an early alfalfa-nodulating genotype”
Claim · model-written summary
The LPU83 nod cluster is syntenic with clusters of alfalfa-nodulating rhizobia.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- Sinorhizobium meliloti
Sinorhizobium melilotie0symbiont - Second interactor
- Sinorhizobium medicae
Sinorhizobium medicaee0symbiont - Outcome
- syntenye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The organization of the cluster showed synteny with those of the alfalfa-nodulating rhizobia, Sinorhizobium meliloti and Sinorhizobium medicae.”
Claim · model-written summary
R. mongolense USDA 1844 nod sequences showed the strongest similarity to LPU83 sequences.
- Taxon
- AlfalfaMedicago sativat0
- Interactor
- Rhizobium mongolense USDA 1844Rhizobium mongolense USDA 1844e0symbiont
- Gene
- nod genese0
- Outcome
- strongest sequence similaritye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the strongest sequence similarity observed was between the partial nod sequences of Rhizobium mongolense USDA 1844 and the corresponding LPU83 nod genes sequences”
t0“Alfalfa”
Claim · model-written summary
The nodEG intergenic phylogeny places LPU83 and R. mongolense 1844 in the same branch.
- Taxon
- AlfalfaMedicago sativat0
- Interactor
- R. mongolense 1844Rhizobium mongolensee0symbiont
- Gene
- nodEGe0
- Outcome
- same branche0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The phylogenetic analysis of the intergenic region nodEG positions strain LPU83 and the type strain R. mongolense 1844 in the same branch”
t0“Alfalfa”
Claim · model-written summary
LPU83 may represent an early alfalfa-nodulating genotype.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- Rhizobium sp. strain LPU83Rhizobium sp.e0symbiont
- Outcome
- early alfalfa-nodulating genotypee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Rhizobium sp. strain LPU83 might represent an early alfalfa-nodulating genotype”
Claim · model-written summary
Wild-type LPU83 nodulation factors have trimeric, tetrameric, and pentameric chitin backbones with substitutions shared with alfalfa- and bean-nodulating rhizobia.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- rhizobiae0symbiont
- Outcome
- trimeric, tetrameric, and pentameric chitin backbonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NF chemical structures obtained for the wild-type strain consist of a trimeric, tetrameric, and pentameric chitin backbone that shares some substitutions with both alfalfa- and bean-nodulating rhizobia.”
Claim · model-written summary
Most LPU83 nodulation factors were sulfated at their reducing terminal residue.
- Taxon
- AlfalfaMedicago sativat0
- Interactor
- Rhizobium sp. strain LPU83Rhizobium sp.e1symbiont
- Outcome
- NFs were sulfatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in strain LPU83 most of the NFs were sulfated in their reducing terminal residue”
t0“Alfalfa”
e1“Rhizobium sp. strain LPU83 might represent an early alfalfa-nodulating genotype”
Claim · model-written summary
No nodulation factors from the nodH mutant LPU83-H were sulfated.
- Taxon
- AlfalfaMedicago sativat0
- Interactor
- Rhizobium sp. strain LPU83Rhizobium sp.e1symbiont
- Gene
- nodHe0
- Outcome
- none of the NFs isolated from the nodH mutant LPU83-H were sulfatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“none of the NFs isolated from the nodH mutant LPU83-H were sulfated”
t0“Alfalfa”
e1“Rhizobium sp. strain LPU83 might represent an early alfalfa-nodulating genotype”
Claim · model-written summary
Sulfate decoration of LPU83 nodulation factors is unnecessary for alfalfa nodulation.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- LPU83e0symbiont
- Outcome
- not necessary for alfalfa nodulatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the sulfate decoration of NFs in LPU83 is not necessary for alfalfa nodulation”