Genetic and Phenotypic Diversity of Microsymbionts Nodulating Promiscuous Soybeans from Different Agro-Climatic Condition
Date
2022
Authors
Mburu, Simon W.
Koskey, Gilbert
Njeru, Ezekiel M
Maingi, John
Kimiti, Jacinta M.
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Genetic Engineering and Biotechnology
Abstract
Background: Global food supply is highly dependent on feld crop production that is currently severely threatened by changing climate, poor soil quality, abiotic, and biotic stresses. For instance, one of the major challenges to
sustainable crop production in most developing countries is limited nitrogen in the soil. Symbiotic nitrogen fxation
of legumes such as soybean (Glycine max (L.) Merril) with rhizobia plays a crucial role in supplying nitrogen sufcient
to maintain good crop productivity. Characterization of indigenous bradyrhizobia is a prerequisite in the selection
and development of efective bioinoculants. In view of this, bradyrhizobia were isolated from soybean nodules in four
agro-climatic zones of eastern Kenya (Embu Upper Midland Zone, Embu Lower Midland Zone, Tharaka Upper Midland
Zone, and Tharaka Lower Midland Zone) using two soybean varieties (SB8 and SB126). The isolates were characterized
using biochemical, morphological, and genotypic approaches. DNA fngerprinting was carried out using 16S rRNA
gene and restricted by enzymes HaeIII, Msp1, and EcoRI.
Results: Thirty-eight (38) bradyrhizobia isolates obtained from the trapping experiments were placed into nine
groups based on their morphological and biochemical characteristics. Most (77%) of the isolates had characteristics
of fast-grower bradyrhizobia while 23% were slow-growers. Restriction digest revealed signifcant (p<0.015) variation
within populations and not among the agro-climatic zones based on analysis of molecular variance. Principal coordinate analysis demonstrated sympatric speciation of indigenous bradyrhizobia isolates. Embu Upper Midland Zone
bradyrhizobia isolates had the highest polymorphic loci (80%) and highest genetic diversity estimates (H’=0.419)
compared to other agro-climatic zones.
Conclusion: The high diversity of bradyrhizobia isolates depicts a valuable genetic resource for selecting more efective and competitive strains to improve promiscuous soybean production at a low cost through biological nitrogen
fxation.
Description
Article
Keywords
Principal coordinate analysis, Shannon’s information index, Bradyrhizobia, 16S rRNA gene, ARDRA
Citation
Mburu, S. W., Koskey, G., Njeru, E. M., Ombori, O., Maingi, J., & Kimiti, J. M. (2022). Genetic and phenotypic diversity of microsymbionts nodulating promiscuous soybeans from different agro-climatic conditions. Journal of Genetic Engineering and Biotechnology, 20(1), 1-15.