Strains of Mesorhizobium amorphae and Mesorhizobium tianshanense, carrying symbiotic genes of common chickpea endosymbiotic species, constitute a novel biovar (ciceri) capable of nodulating Cicer arietinum.
OBJECTIVE
To identify several strains of Mesorhizobium amorphae and Mesorhizobium tianshanense nodulating Cicer arietinum in Spain and Portugal, and to study the symbiotic genes carried by these strains.


RESULTS
The sequences of 16S-23S intergenic spacer (ITS), 16S rRNA gene and symbiotic genes nodC and nifH were analysed. According to their 16S rRNA gene and ITS sequences, the strains from this study were identified as M. amorphae and M. tianshanense. The type strains of these species were isolated in China from Glycyrrhiza pallidiflora and Amorpha fruticosa nodules, respectively, and are not capable of nodulating chickpea. These strains carry symbiotic genes, phylogenetically divergent from those of the chickpea isolates, whose nodC and nifH genes showed more than 99% similarity with respect to those from Mesorhizobium ciceri and Mesorhizobium mediterraneum, the two common chickpea nodulating species in Spain and Portugal.


CONCLUSIONS
The results from this study showed that different symbiotic genes have been acquired by strains from the same species during their coevolution with different legumes in distinct geographical locations.


CONCLUSIONS
A new infrasubspecific division named biovar ciceri is proposed within M. amorphae and M. tianshanense to include the strains able to effectively nodulate Cicer arietinum.
Rivas
R
R
Departamento de Microbiología y Genética, Universidad de Salamanca, Salamanca, Spain.
Laranjo
M
M
Mateos
P F
PF
Oliveira
S
S
Martínez-Molina
E
E
Velázquez
E
E
D020561:Alphaproteobacteria / Q000145:classification* / Q000235:genetics / Q000502:physiology*; D029863:Cicer / Q000382:microbiology* / Q000502:physiology; D004269:DNA, Bacterial / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005798:Genes, Bacterial; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics; D010802:Phylogeny; D011174:Portugal; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D053204:Root Nodules, Plant / Q000382:microbiology*; D013030:Spain; D013559:Symbiosis
D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D012336:RNA, Ribosomal, 16S; D010088:Oxidoreductases; C029130:nitrogenase reductase; D017351:N-Acetylglucosaminyltransferases