20971905
not annotated - annotated - LINNAEUS only
The nodulation of alfalfa by the acid-tolerant Rhizobium sp. strain LPU83 does not require sulfated forms of lipochitooligosaccharide nodulation signals.
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.
Ann file
T1 Species 47 73 Rhizobium sp. strain LPU83
N1 Reference T1 Taxonomy:348824
T2 Species 662 688 Rhizobium sp. strain LPU83
N2 Reference T2 Taxonomy:348824
T3 Species 733 740 alfalfa
N3 Reference T3 Taxonomy:3879
T4 Species 752 772 Leucena leucocephala
N4 Reference T4 Taxonomy:3866
T5 Species 896 903 alfalfa
N5 Reference T5 Taxonomy:3879
T6 Species 925 947 Sinorhizobium meliloti
N6 Reference T6 Taxonomy:382
T7 Species 952 973 Sinorhizobium medicae
N7 Reference T7 Taxonomy:110321
T8 Species 1074 1104 Rhizobium mongolense USDA 1844
N8 Reference T8 Taxonomy:57676
T9 Species 1127 1132 LPU83
N9 Reference T9 Taxonomy:348824
T10 Species 1228 1233 LPU83
N10 Reference T10 Taxonomy:348824
T11 Species 1254 1272 R. mongolense 1844
N11 Reference T11 Taxonomy:57676
T12 Species 1314 1340 Rhizobium sp. strain LPU83
N12 Reference T12 Taxonomy:348824
T13 Species 1366 1373 alfalfa
N13 Reference T13 Taxonomy:3879
T14 Species 1630 1635 LPU83
N14 Reference T14 Taxonomy:348824
T15 Species 1748 1755 LPU83-H
N15 Reference T15 Taxonomy:348824
T16 Species 1851 1856 LPU83
N16 Reference T16 Taxonomy:348824
T17 Species 1878 1885 alfalfa
N17 Reference T17 Taxonomy:3879
T18 Species 18 25 alfalfa
N18 Reference T18 Taxonomy:3879
T19 Species 1563 1570 alfalfa
N19 Reference T19 Taxonomy:3879