Genetic analysis for biological nitrogen fixation (BNF) in cowpea

Acta Scientiarum. Agronomy, 2019

The objectives of the present study were to construct a cowpea genetic map using the F2 population resulting from the cross IC-1 x BRS Marataoã, based on single nucleotide polymorphism (SNP) markers, and to map the cpi gene, with additional reference to introgression with the consensus map of species, aiming to identify markers for assisted selection to develop more efficient cultivars for BNF. The parents and 89 F2 plants were genotyped with 51,128 SNP markers, of which 910 polymorphic markers were used to construct the map. The results revealed 11 linkage groups, with an average of 82 markers per chromosome and average distance of 1.26 cM between markers. Recombination analysis of the SNPs indicated that markers 2_12850 and 2_00188, located in linkage group 11, flanked the cpi gene at a distance of 6.7 cM and 5.64 cM, respectively. The introgression of linkage group 11 with the cowpea reference map revealed short distances (from zero to 0.6 cM) for these markers, indicating a stro...

Journal of Biology, Agriculture and Healthcare, 2015

Field experiment was conducted at Mampong Campus of the University of Education to determine the yield and nitrogen fixation potential of some cowpea lines. Nine lines plus Asontem variety were studied in a Randomized Complete Block Design with four replications. The results showed that all the lines nodulated freely with the natural rhizobia in the soil. There was significant differences (P<0.05) in the nodulation abilities of the lines. Number of nodules negatively correlated with nodule dry weight (r= -0.38) whiles the amount of nitrogen fixed positively correlated with total seed yield (r= 0.94). Line IT97K-506-1 produced the highest number of nodules per plant but did not fix the highest amount of nitrogen. Lines IT97K-566-18 and IT97K-570-18 which contained the highest amount of nitrogen (4.43 and 4.70kgN/ha) respectively in their residue also produced the highest seed yield (3.58 and 3.61t/ha) respectively. The results showed that lines IT97K-570-18 and IT97K-566-18 have h...

Sustainable Agriculture Research

Nitrogen is a major plant nutrient which is most limiting in the soil due to soil losses of mineral nitrogen (N) form. To ensure availability of nitrogen in the soil, the study was conducted to screen four cowpea genotypes for Biological Nitrogen Fixation (BNF) and their contribution to maize yield in maize- cowpea rotation. The cowpea genotypes used were mutants LT11-3-3-12 (LT) and BB14-16-2-2 (BB) and their parental varieties Lutembwe (LTPRT) and Bubebe (BBPRT) respectively. Trials were established at two sites (Chisamba and Batoka) of different soil types. The Randomized Complete Block Design (RCBD) with three replications was used. Labelled 15N urea was applied at 20kgNha-1 on the four cowpea genotypes during 2015/16 growing season. Cowpea plant parts were dried and milled for 15N isotopic analysis. The data collected included Nitrogen content and atom % 15N excess in the fixing cowpea genotypes and non-nitrogen fixing pearl millet to determine total nitrogen derived from the a...

Physiology and Molecular Biology of Plants, 2020

With legumes, symbiotic N 2 fixation can meet the species N demand and reduce the over-reliance on chemical fertilizers in tropical regions where N deficiency is a major factor limiting crop yields and increased agricultural sustainability. Therefore, to optimize the use of cowpea (Vigna unguiculata L. Walp) germplasm in effective breeding, evaluation of genetic diversity and quantification of N 2 fixation are essential prerequisites. The aim of this study was to explore the level of diversity using SSR markers and N 2-fixing traits in a set of cowpea germplasm grown in Ghana. We analysed 49 cowpea accessions collected from Northern Ghana using qualitative vegetative and N 2 fixation traits, and simple sequence repeat (SSR) markers. Experimental field results revealed considerable morpho-physiological variation for plant growth habits, grain yield and symbiotic performance between and among the cowpea accessions. Results from both the 15 N natural abundance and ureides in the xylem sap were able to descriminate between high and low levels of N 2 fixation in cowpea accessions. Five subpopulations were identified within accessions inferred from STRUCTURE 2.3.4. A general linear model was used to assess the association of SSR markers with N 2-fixing traits. There were significant (p B 0.05) links between SSR markers and symbiosis-related traits such as nodule number, nodule dry weight, shoot dry weight, N-fixed, N derived from air (Ndfa), and relative uried-N (RU-N).

AFRICAN JOURNAL OF BIOTECHNOLOGY

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.

Frontiers in Agronomy, 2022

To evaluate cowpea genotypic differences in response to inoculation with Bradyrhizobium sp. strains BR 3267 and CB756 in the field, 15 genotypes were assessed for N2 fixation using 15N natural abundance and assays of xylem N solutes (ureides, nitrates, and amino-N). Carbon isotope discrimination (δ13C) was used as a surrogate for water use efficiency and grain yield determined at maturity. Within each location, the tested cowpeas elicited contrasting responses to inoculation with either Bradyrhizobium strains. For example, inoculating Apagbaala and IT90K-277-2 with strain BR 3267 doubled N-fixed and grain yield at Nyankpala when compared to inoculation of the same genotypes with strain CB756, whereas the inoculation of Padituya with strain CB756 increased those same parameters relative to non-inoculation. Similar contrasting results were also obtained at Savelugu and Gbalahi, where bacterial inoculation with each strain resulted in up to a five-fold increase in N-fixed and a four-fo...

Biology and Fertility of Soils, 2002

The objective of this work was to study the genetics of the nodulation and biological nitrogen fixation (BNF) characteristics of Brazilian soybean cultivars. Four cultivars were identified with different capacities for BNF: J-200 and Bossier (high), Embrapa 20 (medium) and Embrapa 133 (low), and all possible crosses, including reciprocals, were carried out to obtain the F1, F2 and F3 generations. Three experiments were performed simultaneously, under greenhouse conditions, with the restricted set of generations P1, P2, F2 and F3, and plants were evaluated for nodulation (nodule number, NN, and nodule dry weight, NDW) and plant growth (shoot dry weight, SDW). No significant differences between reciprocal and direct effects were observed, therefore all data from F2, as well as from F3 plants were pooled. The frequency distributions for the tested variables in the F3 families were normal, with no evidences of discontinuities, consistent with polygenic inheritance. In the J-200 × Embrapa 133 and Bossier × Embrapa 133 crosses, the significance of the models for means and variances was less frequent, but was eventually observed for NN and NDW. In the other two experiments, there was a predominance of genetic additive (d) and/or genetic additive variance (D) effects for most of the tested variables, except for NDW in the cross of J-200 × Bossier. Genetic dominant effects (h) and/or genetic dominance variance (H) were detected for all variables in the cross Embrapa 20 × Embrapa 133 and for NDW/NN for Bossier × Embrapa 20. Additive × additive epistatic (i) and interaction genotype × microenvironment effects were less important in all experiments. The narrow-sense heritabilities (h n 2 ) estimates ranged from 39% to 77%, with higher values for NN and NDW in Bossier × Embrapa 20 and for SDW in Embrapa 20 × Embrapa 133; these were high values when compared to other legumes. The prediction of the genetic potential to generate superior inbred lines for nodulation and BNF capacity indicated that selection could be more effective for crosses Bossier × Embrapa 20, and Embrapa 20 × Embrapa 133.

Biology and Fertility of Soils, 2003

Nodulating bacteria from the family Rhizobiaceae are common in the semi-arid tropics around the world. The Brazilian semi-arid region extends over 95 million hectares of which only 3% is suitable for irrigation, therefore leaving an immense dryland area to be exploited by peasant farmers, who often lack appropriate technologies for sustainable management. Cowpea is an important crop in this area, representing the staple protein source for human nutrition. This work aimed to identify rhizobial strains capable of guaranteeing sufficient nitrogen derived from biological fixation for cowpea cultivated in dryland areas, evaluating not just efficiency but also the ecological parameters of competitiveness and survival in the soil. Grain yield and nodulation parameters showed that strain BR 3267 is capable of establishing efficient nodulation, improving both yield and total N accumulated in grain. Cowpea inoculated with strain BR 3267 showed grain productivity similar to plants receiving 50 kg of N per hectare, which is the amount of fertilizer commonly used in the north-east region. These characteristics associated with previously determined ecological properties makes strain BR 3267 an important resource for the optimization of biological nitrogen fixation in cowpea in the dryland areas of the semi-arid tropics. Data on the dynamics of rhizobial populations in such areas have shown that (1) the naturalized rhizobium population is very small and, by themselves, do not promote proper nodulation and, (2) the inoculant rhizobia do not persist between crops. Such characteristics represent an opportunity for the introduction of superior rhizobia strains, such as BR 3267, during the cowpea crop.

Biology and Fertility of Soils, 2010

In this study, 30 cowpea genotypes were assessed for symbiotic N 2 fixation in 2005, and 15 of them were reevaluated in 2006 using the 15 N natural abundance technique. Shoot dry matter yield of cowpea genotypes increased significantly in cvs. Vuli-1, Glenda, IT93K-2045-29, IT90K-59, Omondaw, Apagbaala, and IT84S-2246 in 2005 producing about 3.0 to 3.6-fold more biomass relative to cv. Vallenga. In 2006, seven out of the 15 cowpea genotypes tested (namely, IT97K-499-39, TVu11424, Botswana White, IT84S-2246, Sanzie, Brown Eye, and Glenda) also produced more dry matter than cv. CH14. Shoot δ 15 N values ranged from −0.58‰ to 1.49‰ in 2005, and −1.51‰ to 1.40‰ in 2006, and these resulted in %Ndfa values of 63.5-86.7% and 56.2-96.3%, respectively. The amount of N-fixed was 49-178 kg N ha −1 in 2005 and 62-198 kg N ha −1 in 2006. Furthermore, there was a direct relationship between the level of symbiotic N nutrition and plant growth, and between grain yield and amount of N-fixed in 2005 and 2006.

1978