Genetic diversity of indigenous Rhizobium leguminosarum bv. viciae isolates nodulating two different host plants during soil restoration with alfalfa

Abstract

A total of 360 Rhizobium leguminosarum bv. viciae strains was isolated from three brown-coal mining restoration fields of different age and plant cover (without and in the first and second year of alfalfa, Medicago sativa, cultivation) using two host species (Vicia hirsuta and Pisum sativum) as capture plants. The strains were genetically typed by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-generated 16S-23S ribosomal DNA intergenic spacer regions (IGS-RFLP) and characterized by plasmid profiles and RFLP analysis of amplified nodABC genes. The R. leguminosarum bv. viciae population was dominated by the same group of strains (irrespective of the trap plant used). According to type richness, the genetic diversity of indigenous R. leguminosarum in the second year of restoration was lower than in the first year and it resembled that of the fallow field, except for plasmid types, in which it was higher than that of the fallow field. Some of the less frequent nodABC genotypes were associated with distinct chromosomal IGS genotypes and symbiotic plasmids (pSyms) of different sizes, indicating that horizontal transfer and rearrangements of pSym can occur in natural environments. However, the dominant pSym and chromosomal genotypes were strictly correlated suggesting a genetically stable persistence of the prevailing R. leguminosarum bv. viciae genotypes in the absence of its host plant.

Compatibility of Rhizobial Genotypes within Natural Populations of Rhizobium leguminosarum Biovar viciae for Nodulation of Host Legumes

“…Correlations between chromosomal and Sym plasmid genotypes have been previously observed within pea R. leguminosarum bv. viciae populations (11,23,50,52). This suggests that both components of the rhizobial genome are involved in competitiveness for nodule formation with peas.…”

“…A previous study has shown that associations constructed by introduction of the same Sym plasmid in different recipient strains varied in competitiveness for nodulation of pea plants, indicating that both components of the genome were involved (5). Several reports have shown that the Sym plasmid is not strictly associated with the chromosomal background in natural populations of R. leguminosarum (14,23,25,30,38,50,52). The analysis of the genetic structure of populations of R. leguminosarum bv.…”

Assessing the Relative Effects of Geographic Location and Soil Type on Microbial Communities Associated with Straw Decomposition

“…About 120 transformants were randomly selected for each straw sample in black soil and subjected to restriction fragment length polymorphism (RFLP) analysis (40). To do this, the cloned 16S rRNA gene fragments were PCR amplified using two primers located in the vector, RV-M (5=-GAGCGGA TAATTTCACACAGG-3=) and M13-47 (5=-CGCCAGGGTTTTCCCAG TCACGA-3=), and PCR products were digested by two enzymes, Sau3AI and HhaI.…”

Occurence and host specificity of indigenous rhizobia from soils of São Paulo State, Brazil

“…Cultivated areas containing Neonotonia wightii (Lopes et al, 1972), peanut (Giardini et al, 1985;Lombardi et al, 1992) or green manure legumes (Chada & De Polli, 1988;Rodrigues et al, 1994, Zilli et al, 2004 were capable of maintaining rhizobial communities that were highly infective for their host plants and well adapted to soil conditions. Several studies indicated that the rhizobial communities can be affected by the properties of the soil and by the host plants (Palmer & Young, 2000, Zhang et al, 2001Laguerre et al, 2003), as well as by soil tillage (Cattelan & Vidor, 1990;Castro et al, 1993, Carvalho et al, 2004, and crop history (Venkatesvarlu et al, 1997).…”