Morphological and Genetic Diversity of Rhizobia Nodulating Cowpea (Vigna unguiculataL.) from Agricultural Soils of Lower Eastern Kenya

Abstract

Limited nitrogen (N) content in the soil is a major challenge to sustainable and high crop production in many developing countries. The nitrogen fixing symbiosis of legumes with rhizobia plays an important role in supplying sufficient N for legumes and subsequent nonleguminous crops. To identify rhizobia strains which are suitable for bioinoculant production, characterization of rhizobia is a prerequisite. The objective of this study was to assess the morphological and genetic diversity of rhizobia that nodulates cowpea in agricultural soils of lower eastern Kenya. Twenty-eight rhizobia isolates were recovered from soil samples collected from farmers' fields in Machakos, Makueni, and Kitui counties in lower eastern Kenya and characterized based on morphological characteristics. Thirteen representative isolates were selected and characterized using BOX repetitive element PCR fingerprinting. Based on the dendrogram generated from morphological characteristics, the test isolates were distributed into two major clusters at a similarity of 75%. Phylogenetic tree, based on BOX repetitive element PCR, grouped the isolates into two clusters at 90% similarity level. The clustering of the isolates did not show a relationship to the origin of soil samples, although the isolates were genetically diverse. This study is a prerequisite to the selection of suitable cowpea rhizobia to develop bioinoculants for sustainable crop production in Kenya.

Genetic and Morphological Diversity of Indigenous Bradyrhizobium Nodulating Soybean in Organic and Conventional Family Farming Systems

“…The amplification of the target 16S rDNA gene resulted to a single band of 1.5 kb in size. Previous results reported that the band size obtained correspond to the expected size due to the use of primers specific to rhizobia (Zhang et al, 2014;Ondieki et al, 2017). The molecular analysis findings demonstrated a high variation in the 38 indigenous representatives isolates which is an indication that the soils from the trapping farms harbor populations of highly diverse bradyrhizobia species.…”

Potential of Native Rhizobia to Improve Cowpea Growth and Production in Semiarid Regions of Kenya

“…The pure isolates were grouped according to their morphological and biochemical features as described by Ondieki et al (2017). Individual colonies incubated for 48 h were characterized based on their size, shape, color, elevation, transparency, and margin.…”

Diversidade e eficiência simbiótica de rizóbios de solos de clima semiárido tropical com diferentes fertilidades

“…O estabelecimento da simbiose com rizóbios de crescimento rápido e lento deve-se à baixa especificidade simbiótica do feijão-caupi. A nodulação do feijão-caupi é frequentemente estabelecida com isolados de crescimento lento em diversos ambientes (TAMPAKAKI et al, 2017;CHIDEBE et al, 2018;FERREIRA et al, 2019), porém a predominância de nodulação por rizóbios de crescimento rápido vem sendo cada vez mais observada (ONDIEKI et al, 2018;GIRIJA et al, 2018).…”

“…Além disto, a produção de muco dos isolados deste trabalho provavelmente funcionou como outra importante estratégia de adaptação e resistência ao clima hostil e a estresses ambientais, independentemente da quantidade de muco produzido (OLIVEIRA et al, 2014), sugerindo uma alta vantagem competitiva no estabelecimento da simbiose (ONDIEKI et al, 2018).…”