Diverse Mesorhizobium plurifarium populations native to Mexican soils.
Forty-six Mesorhizobium strains associated with the leguminous plants Leucaena leucocephala and Sesbania herbacea in an uncultivated Mexican field were characterized using a polyphasic approach. The strains were identified as Mesorhizobium plurifarium based upon the close relationships with the reference strains for this species in PCR-based restriction fragment length polymorphism analyses, sequencing of 16S rRNA genes, multilocus enzyme electrophoresis, and DNA-DNA hybridization. Although the strains isolated from both plants formed the same group in multilocus enzyme electrophoresis and cross-nodulations were observed in the laboratory, different electrophoretic types were obtained from the two plants grown in natural soils, indicating the existence of a preferable association between the plants and the rhizobia. The M. plurifarium strains from Mexico and the reference strains from Africa and Brazil formed different phenotypic clusters in a numerical taxonomy. The Mexican strains did not grow at 37 degrees C and were sensitive to salty-alkaline conditions, while the reference strains from Africa and Brazil grew at 42 degrees C and were more resistant to salty-alkaline conditions. These results demonstrate that both the plants and environmental factors affected the evolution of rhizobia and that the Mexican strains had adapted to the neutral soils and the cool climate where they were isolated.
Departamento de Microbiología, Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, 11340 Carpio y Plan de Ayala S/N, México D.F., México. ewang@encb.ipn.mx
En Tao
ET
Wang
Feng Ling
FL
Kan
Zhi Yuan
ZY
Tan
Ivonne
I
Toledo
Wen Xin
WX
Chen
Esperanza
E
Martínez-Romero
D000220:Adaptation, Biological; D020561:Alphaproteobacteria / Q000145:classification* / Q000254:growth & development / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000032:analysis / Q000302:isolation & purification; D044822:Biodiversity; D005075:Biological Evolution; D004275:DNA, Ribosomal / Q000737:chemistry / Q000302:isolation & purification; D007887:Fabaceae / Q000382:microbiology*; D014644:Genetic Variation; D006863:Hydrogen-Ion Concentration; D008800:Mexico; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D009997:Osmotic Pressure; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012965:Sodium Chloride; D012988:Soil Microbiology; D013696:Temperature
D001426:Bacterial Proteins; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012965:Sodium Chloride