Genetic diversity of common bean (Phaseolus vulgaris L.) nodulating rhizobia in Nepal

Adhikari, D. and Itoh, K and Suyama, K (2012) Genetic diversity of common bean (Phaseolus vulgaris L.) nodulating rhizobia in Nepal. Plant and Soil. pp. 1-13.

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Background and Aims This study was conducted to reveal the genetic diversity of common bean (Phaseolus vulgaris L.) nodulating rhizobia in various agroecological regions in Nepal. Method A total of 63 strains were isolated from common bean grown in the soils collected from seven bean fields in Nepal and characterized based on the partial sequences of 16S–23S internal transcribed spacer (ITS) regions, 16S rDNA, nodC, and nifH. Symbiotic properties of some representative strains with host plants were examined to elucidate their characteristics in relation to genotype and their origin. Results The isolated strains belonged to Rhizobium leguminosarum, Rhizobium etli, Rhizobium phaseoli, and one unknown Rhizobium lineage, all belonging to a common symbiovar (sv.) phaseoli. Nine ITS genotypes were detected mainly corresponding to a single site, including a dominant group at three sites harboring highly diverse multiple ITS sequences. Three symbiotic genotypes corresponded to a geographical region, not to the ribosomal DNA group, suggesting horizontal transfer of symbiotic genes separately in each region. Great differences in nitrogenase activity and nodule forming ability among the strains irrespective of their species and origin were observed. Conclusions Nepalese Himalaya harbor phylogenetically highly diverse and site-specific strains of common bean rhizobia, some of which could have high potential of symbiotic nitrogen fixation.

Item Type: Article
Uncontrolled Keywords: Nepal – Common bean – Rhizobium – Genetic diversity – ARA – Multiple ITS bands
Author Affiliation: Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue Shimane, 690-8504, Japan, Nepal Agricultural Research Council, Singhadurbar Plaza, Kathmandu, Nepal
Subjects: Crop Improvement
Divisions: Common Bean
Depositing User: Mr. SanatKumar Behera
Date Deposited: 12 Nov 2012 04:55
Last Modified: 12 Nov 2012 04:55
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