Tropentag, October 5 - 7, 2011 in Bonn "Development on the margin"

Genetic Identification of Rhizobia Isolates: Behaviour on Bean (Phaseolus vulgaris L.) Genotypes

¹Central University of Las Villas, Faculty of Agricultural Sciences, Cuba
²University of Rostock, Faculty of Agricultural and Environmental Sciences, Germany
³Universidad Nacional de Loja, Area de Recursos Naturales, Ecuador
⁴Gent University, Laboratory of Microbiology, Belgium
⁵Katholieke Universiteit Leuven, Centre for Microbial and Plant Genetics, Belgium

Abstract

The work was carried out with the aim to identify and characterise isolates of Rhizobium genus from 13 sampling areas in central provinces of Cuba (Sancti Spiritus, Villa Clara and Cienfuegos), and to determine the effect of the isolates on phenotypic and growth parameters of common bean genotypes under controlled conditions. The morphological analysis was based on determining the differences of the colonies obtained from isolation, which evaluated the Gram stain, growth type, colour, slime production, edge and elevation. The genetic identification of isolates was performed by molecular tools using 16S rRNA gene sequencing. Under controlled conditions the nodulation, phenotypic parameters, biomass and nitrogen content were evaluated on ICA Pijao and BAT-304 common bean genotypes. The results showed a wide morphological diversity of native strains in the soils of central Cuba. A total of 33 isolates showed different characteristics in at least one parameter measured. A total of 22 sequences were analysed for genetic identification, turning out six genus of bacteria matching to Arthrobacter, Chryseobacterium, Enterobacter, Stenotrophomonas, Pseudomonas and Rhizobium genus. Rhizobia were the only bacteria with differences at species level. From eight sequences aligned belonging to the genus Rhizobium, four species (Rhizobium sp., R. etli, R. pisi and R. radiobacter) were identified including the first report of R. pisi for Cuban soils. Phenotypic analysis showed the beneficial effect of the species R. etli and R. pisi, respectively, increasing the growth parameters, biomass production and nitrogen content on bean genotypes. Genotypic variability demonstrated the close correlation among these strains and genotype BAT-304 compared with ICA Pijao.

Keywords: Genetic identification, growth parameters, nitrogen content, Phaseolus vulgaris, Rhizobium, strains

Contact Address: Bettina Eichler-Loebermann, University of Rostock, Faculty of Agricultural and Environmental Sciences, J. von Liebig Weg 6, 18059 Rostock, Germany, e-mail: bettina.eichleruni-rostock.de