Felix Dakora - Academia.edu (original) (raw)

Papers by Felix Dakora

Scientific Reports

In most legumes, the rhizobial symbionts exhibit diversity across different environments. Althoug... more In most legumes, the rhizobial symbionts exhibit diversity across different environments. Although common bean (Phaseolus vulgaris L.) is one of the important legumes in southern Africa, there is no available information on the genetic diversity and N2-fixing effectiveness of its symbionts in Malkerns, Eswatini. In this study, we assessed the phylogenetic positions of rhizobial microsymbionts of common bean from Malkerns in Eswatini. The isolates obtained showed differences in morpho-physiology and N2-fixing efficiency. A dendrogram constructed from the ERIC-PCR banding patterns, grouped a total of 88 tested isolates into 80 ERIC-PCR types if considered at a 70% similarity cut-off point. Multilocus sequence analysis using 16S rRNA, rpoB, dnaK, gyrB, and glnII and symbiotic (nifH and nodC) gene sequences closely aligned the test isolates to the type strains of Rhizobium muluonense, R. paranaense, R. pusense, R. phaseoli and R. etli. Subjecting the isolates in this study to further de...

Microorganisms

Improving the efficiency of the legume–rhizobia symbiosis in African soils for increased grain yi... more Improving the efficiency of the legume–rhizobia symbiosis in African soils for increased grain yield would require the use of highly effective strains capable of nodulating a wide range of legume plants. This study assessed the photosynthetic functioning, N2 fixation, relative symbiotic effectiveness (%RSE) and C assimilation of 22 jack bean (Canavalia ensiformis L.) microsymbionts in Eswatini soils as a first step to identifying superior isolates for inoculant production. The results showed variable nodule number, nodule dry matter, shoot biomass and photosynthetic rates among the strains tested under glasshouse conditions. Both symbiotic parameters and C accumulation differed among the test isolates at the shoot, root and whole-plant levels. Although 7 of the 22 jack bean isolates showed much greater relative symbiotic efficiency than the commercial Bradyrhizobium strain XS21, only one isolate (TUTCEeS2) was statistically superior to the inoculant strain, which indicates its poten...

Kluwer Academic Publishers eBooks, Dec 27, 2005

African Journal of Biotechnology, Sep 21, 2011

The aim of this study was to evaluate plant growth, grain yield and symbiotic N contribution by 3... more The aim of this study was to evaluate plant growth, grain yield and symbiotic N contribution by 32 cowpea genotypes, at Taung in South Africa. The data from a 2-year field study conducted in 2005 and 2006 showed that genotypes Fahari, Pan 311 and Glenda exhibited the highest dry matter yield and N contribution as they produced 2.9-, 2.7-and 3.5-fold more dry matter than cv. ITH98-46 and yielded 2.7-, 2.2-and 3.2-fold more N than cultivar ITH98-46 from IITA. Except for Benpila, all the 32 cowpea genotypes derived between 52.0 and 80.9% of their N nutrition from symbiotic fixation in 2005, with IT82D-889, Botswana White, IT93K-2045-29 and Ngonji exhibiting the highest %Ndfa values. The genotype Fahari showed the highest amount N-fixed (182 kg N-fixed/ha), followed by Pan 311, Glenda, TVu11424 and Mamlaka which contributed 160, 146, 130 and 125 kg N/ha, respectively. Genotypes Pan 311, Fahari and Glenda were among those that produced highest grain yield in 2005 and except for CH14 and IT86S-2246 (which produced 131 kg N/ha each), Fahari, Glenda and Pan 311, were again the highest in symbiotic N contribution (112, 106 and 105 kg N/ha, respectively). Grain yield was similarly high in Glenda, Pan 311 and Fahari (3.3, 3.1 and 2.9 t/ha, respectively) in 2006. In general, these data show that genotypes that fixed more N also produced more biomass and grain yield and are therefore, the best candidates for inclusion in cropping systems as biofertilizers.

Annals of Botany, 1995

A combination of physiological and structural measurements made on nodulated cowpea and soybean p... more A combination of physiological and structural measurements made on nodulated cowpea and soybean plants cultured with roots in different p02 permitted the expression of da ta in various ways. Values of leghemoglobin concentration and nitrogenase activity from the two legurnes were expressed conventionally either on a per plant or per gram nodule fresh weight basis, and where microscopy was done, on the basis of nitrogenase-containing, N 2-fixing units (i.e. per bacteroid, per infected cell, or per gram infected tissue). In both legumes, acetylene reduction, N fixed and ureide content expressed on the basis of whole plants or per nitrogenase-containing units were very significantly correlated with values ofleghaemoglobin concentrations expressed in a similar manner. The use of mathematical correlations in this study involving leghaemoglobin concentrations and various indices of N 2 fixation indicated a strong functional relationship between the two pro teins in symbiotic legumes. These findings confirm previous suggestions that leghaemoglobin and the nitrogenase complex are two pro teins closely associated with N 2-fixingefficiency in legurne root nodules.

Springer eBooks, Aug 19, 2008

Photosynthetica, Dec 1, 2015

This study evaluated the relationship between photosynthetic carbon accumulation and symbiotic ni... more This study evaluated the relationship between photosynthetic carbon accumulation and symbiotic nitrogen nutrition in young fully expanded leaves of 30 nodulated cowpea genotypes grown in the field at Manga, Ghana, in 2005 and 2006. Estimates of fixed-N in photosynthetic leaves revealed greater symbiotic N in genotypes with higher photosynthetic rates and increased leaf transpiration rate/efficiency. There was also greater C accumulation in genotypes with higher symbiotic N and/or total N. Additionally, genotypes with high contents of C per unit of leaf total N exhibited greater C per unit of leaf N-fixed. The C/N and C/Rubisco-N ratios were generally similar in their magnitude when compared to the C/N-fixed ratio due possibly to the fact that Rubisco accounts for a high proportion of photosynthetic leaf N, irrespective of whether the enzyme was formed from soil N or symbiotic N. Cowpea genotypes that relied heavily on soil N for their N nutrition exhibited much higher C/N-fixed ratios, while conversely those that depended more on symbiosis for meeting their N demands showed markedly lower C/N-fixed values.

Environmental and Experimental Botany, Dec 1, 2003

Nitrate deposition from anthropogenic activities into nutrient impoverished soils of Mediterranea... more Nitrate deposition from anthropogenic activities into nutrient impoverished soils of Mediterranean ecosystems represents a significant income to their N economy, which may potentially increase the sensitivity of those typically UV-B (280 Á/315 nm) resilient plants from these ecosystems with superior photosynthetic rates especially to increases in solar UV-B flux due to ozone depletion. This proposal was examined by exposing nodulated Podalyria calyptrata seedlings for 6-months in nitrate deficient and nitrate replete sand culture to biologically effective UV-B (UV-B BE) supplements approximating 40 and 77% above clear-sky background (control) at an outdoor site. Leaf photosynthesis and chemical composition of purely symbiotic plants were unaffected by increased UV-B BE. Conversely, nodulated plants that received nitrate supplements displayed a linear reduction in stomatal conductance (g S) but non-linear asymptotic reductions in light-saturated net CO 2 assimilation rate (A sat), apparent carboxylation efficiency (ACE) and nitrogen use efficiency (NUE) with increased UV-B BE. RuBP regeneration limitations on CO 2 assimilation were not apparent, since A sat at saturating internal leaf CO 2 concentrations displayed insignificant depressions with increased UV-B BE. Nor was there any suggestion of diminished light absorption capacity of antenna complexes, or of photosynthetic inhibition due to starch accumulation, since leaf chlorophyll and carotenoid contents and non-structural carbohydrate concentrations were insignificantly altered by increased UV-B BE. Also, there seemed unlikely photosynthetic inhibition due to reduced allocation of N to Rubisco with increased UV-B BE in the nitrate-fed plants, since both ACE and A sat were negatively correlated with leaf N content, much of which probably constituted assimilated nitrate according to the less negative d 15 N values. We suggest that the molecular processes that rendered P. calyptrata plants receiving nitrate supplements more sensitive to photosynthetic inhibition by increased UV-B BE may be related indirectly to their more active metabolic state, this apparent from their elevated respiratory and photosynthetic rates, rather than to any direct UV-B effects on CO 2 uptake and fixation.

Annals of Botany, Nov 1, 1998

Nitrogen-fixing activity in two nodulated African legumes, Bambara groundnut (Vigna subterranea L... more Nitrogen-fixing activity in two nodulated African legumes, Bambara groundnut (Vigna subterranea L.) and Kersting's bean (Macrotyloma geocarpum L.

Functional Plant Biology, 2003

Background: Cowpea is the most important food grain legume in Sub-Saharan Africa. However, no stu... more Background: Cowpea is the most important food grain legume in Sub-Saharan Africa. However, no study has so far assessed rhizobial biodiversity and/or nodule functioning in relation to strain IGS types at the continent level. In this study, 9 cowpea genotypes were planted in field experiments in Botswana, South Africa and Ghana with the aim of i) trapping indigenous cowpea root-nodule bacteria (cowpea "rhizobia") in the 3 countries for isolation, molecular characterisation using PCR-RFLP analysis, and sequencing of the 16S-23S rDNA IGS gene, ii) quantifying N-fixed in the cowpea genotypes using the 15 N natural abundance technique, and iii) relating the levels of nodule functioning (i.e. N-fixed) to the IGS types found inside nodules. Results: Field measurements of N 2 fixation revealed significant differences in plant growth, δ 15 N values, %Ndfa and amounts of N-fixed between and among the 9 cowpea genotypes in Ghana and South Africa. Following DNA analysis of 270 nodules from the 9 genotypes, 18 strain IGS types were found. Relating nodule function to the 18 IGS types revealed significant differences in IGS type N 2-fixing efficiencies. Sequencing the 16S-23S rDNA gene also revealed 4 clusters, with cluster 2 forming a distinct group that may be a new Bradyrhizobium species. Taken together, our data indicated greater biodiversity of cowpea bradyrhizobia in South Africa relative to Botswana and Ghana. Conclusions: We have shown that cowpea is strongly dependant on N 2 fixation for its N nutrition in both South Africa and Ghana. Strain IGS type symbiotic efficiency was assessed for the first time in this study, and a positive correlation was discernible where there was sole nodule occupancy. The differences in IGS type diversity and symbiotic efficiency probably accounts for the genotype × environment interaction that makes it difficult to select superior genotypes for use across Africa. The root-nodule bacteria nodulating cowpea in this study all belonged to the genus Bradyrhizobium. Some strains from Southern Africa were phylogenetically very distinct, suggesting a new Bradyrhizobium species.

South African Journal of Science, Nov 4, 1994

Symbiosis, Feb 1, 2009

Three newly selected strains of Cyclopia rhizobia together with an inoculant strain, which has ne... more Three newly selected strains of Cyclopia rhizobia together with an inoculant strain, which has never been tested in the field with adequate experimental design, was assessed under both nursery and field conditions for symbiotic performance. The three new test strains were initially selected for their superior Nz-fixing abilities under glasshouse conditions, and then evaluated in this study for field performance. Cyclopia subternata Vogel and Cyclopia genistoides (L.) R. Br., which have the potential for producing high quality honeybush tea, were used as host plants in both the nursery and field studies.The effect of seedling inoculation at the nursery level was also examined for the four test strains under nursery conditions. The inoculation of cuttings under nursery conditions produced.significant increases in shoot biomass, shoot %N and shoot N content. More specifically, inoculating C. subternata with strains UCT44b and UCT61a significantly increased shoot biomass and N content relative to strain PPRICI3. Strains UCT44b and UCT61a also showed better nodulation with C. subternata cuttings compared to strains UCHOa and PPRICI3. Field inoculation of Cyclopia increased all growth parameters relative to the uninoculated control, except for leaf %N. Cyclopia subternata inoculated with strains UCT44b, UCT40a and UCT61a produced significantly lower b 15 N values than the uninoculated C. subternata reference plant. Using the 15N natural abundance method, C. subternata was estimated to be gaining about half of its N from N z fixation, while C. genistoides obtained less than half of its N from symbioticnutrition.

New Phytologist, Mar 18, 2003

The view that symbiotic legumes benefit companion and subsequent plant species in intercrop and r... more The view that symbiotic legumes benefit companion and subsequent plant species in intercrop and rotation systems is well accepted. However, the major contributions made separately by legumes and their microsymbionts that do not relate to rootnodule N 2 fixation have been largely ignored. Rhizobia (species of Rhizobium , Bradyrhizobium , Azorhizobium , Allorhizobium , Sinorhizobium and Mesorhizobium) produce chemical molecules that can influence plant development, including phytohormones, lipo-chito-oligosaccharide Nod factors, lumichrome, riboflavin and H 2 evolved by nitrogenase. When present in soil, Nod factors can stimulate seed germination, promote plant growth and increase grain yields of legume and nonlegume crops, as well as stimulate increased photosynthetic rates following plant leaf spraying. Very low concentrations of lumichrome and H 2 released by bacteroids also promote plant growth and increase biomass in a number of plant species grown under field and glasshouse conditions. Rhizobia are known to suppress the population of soil pathogens in agricultural and natural ecosystems and, in addition to forming nodule symbioses with rhizobia, the legume itself releases phenolics that can suppress pathogens and herbivores, solubilize nutrients, and promote growth of mutualistic microbes. Phytosiderophores and organic acid anions exuded by the host plant can further enhance mineral nutrition in the system. This review explores new insights into sole and mixed plant cultures with the aim of identifying novel roles for molecules of legume and microbial origin in natural and agricultural ecosystems.

Frontiers in Agronomy

Field studies on the effect of differing seedcoat colour on plant growth and symbiotic performanc... more Field studies on the effect of differing seedcoat colour on plant growth and symbiotic performance of three Bambara groundnut landraces using the 15N natural abundance technique and ureide analysis in the xylem stream and petiole extracts revealed a consistent pattern in nodule function between ureide levels and shoot δ15N values, as well as between ureide levels and percent N derived from fixation at Gbalahi, Kpalisogu, and Manga. At those three sites, where shoot δ15N was low and percent N derived from fixation high, ureide concentrations in the xylem sap and petiole extracts were also high, indicating that the two techniques were comparatively quite robust in estimating N2 fixation at a higher precision in the test Bambara groundnut landraces. A comparison of the effect of differing seedcoat pigmentation on the concentration of phenolics released by imbibed seeds showed that the Black landrace contained higher levels of flavonoids and anthocyanins, followed by the Red, and lowest...

South African Journal of Botany

Plants

Lessertia frutescens is a multipurpose medicinal plant indigenous to South Africa. The curative a... more Lessertia frutescens is a multipurpose medicinal plant indigenous to South Africa. The curative ability of the medicinal plant is attributed to its rich phytochemical composition, including amino acids, triterpenoids, and flavonoids. A literature review of some of the phytochemical compounds, particularly amino acids, in L. frutescens shows a steady decrease in concentration over the years. The reduction of the phytochemical compounds and diminishing biological activities may be attributed to drought and salt stress, which South Africa has been grappling with over the years. Canavanine, a phytochemical which is associated with the anticancer activity of L. frutescens, reduced slightly when the plant was subjected to salt stress. Like other legumes, L. frutescens forms a symbiotic relationship with plant-growth-promoting rhizobacteria, which facilitate plant growth and development. Studies employing commercial plant-growth-promoting rhizobacteria to enhance growth and biological acti...

Journal of Soil Science and Plant Nutrition, 2022

Acta microbiologica Polonica, 1988

Journal of agricultural science & technology A, 2013

The Cape fynbos is characterised by highly leached, sandy, acidic soils with very low nutrient co... more The Cape fynbos is characterised by highly leached, sandy, acidic soils with very low nutrient concentrations. Plant-available P levels range from 0.4 μg P g -1 to 3.7 μg P g -1 soil, and 1-2 mg N g -1 soil. Despite these low nutrient concentrations, the fynbos is home to 9,030 vascular plant species with 68.7% endemicity. How native plant species survive such low levels of available P is intriguing, and indeed the subject of this review. In the fynbos soils, P is easily precipitated with cations such as Fe and Al, forming Al-P and Fe-P in acidic soils, or Ca-P in neutral-to-alkaline soils. The mechanisms for promoting P availability and enhancing P nutrition include the development of mycorrhizal symbiosis (with 80%-90% of higher plants, e.g., Cyclopia, Aspalathus, Psoralea and Leucadendron etc.) which exhibits 3-5 times much greater P acquisition than non-mycorrhizal roots. Formation of cluster roots by the Leguminosae (Fabaceae) and their exudation of Kreb cycle intermediates (or...