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Kersting's groundnut (Macrotyloma geocarpum Harms) is a neglected, endangered food and medicinal legume in Africa. Efforts to harness the benefits of the legume-rhizobia symbiosis have focused on few major legumes to the neglect of underutilized ones such as Kersting's groundnut. This study assessed plant growth, N-fixed and grain yield of five Ker...
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The nitrogen-fixing bacterial strain UFLA 01-1174T was isolated from nodules of Campsiandra laurilifolia Benth. originating from the Amazon region, Brazil. Its taxonomic position was defined using a polyphasic approach. Analysis of the 16S rRNA gene placed the strain in the Bradyrhizobium genus, the closest species being B. guangdongense CCBAU 5164...
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... One of the key studies in this area highlights the phenotypic and genotypic characterization of rhizobia isolated from peanut root nodules in Moroccan soils. This research provides insights into the diversity of rhizobial strains and their potential applications in improving peanut crop yields, especially in saline and acidic soils [25]. Furthermore, the role of rhizobia in improving the ecological resource-use efficiency of legumes, such as the endangered Kerstings groundnut, has been explored. ...
The aggravation of soil salinization has become one of the major factors that threaten crop growth and yield. Rhizobia, as an important biological nitrogen-fixing microorganism, can establish symbiotic relationships with legumes to improve their nitrogen-fixing ability and stress tolerance. Trehalose, a non-reducing disaccharide that is widely found in bacteria, fungi, and plants, can protect cellular structures and maintain the viability of cells under stress conditions. However, it remains to be determined whether the endogenous trehalose level in rhizobia could affect its stress tolerance and nitrogen-fixing capabilities. In this study, we constructed four engineered rhizobial strains to examine the effects of the overexpression and knockout of the trehalose synthesis genes otsA/otsB in the rhizobium strain CCBAU25338 on its salt tolerance and nitrogen-fixing capacity. The results indicated that the overexpression of otsA, rather than the otsB gene, significantly enhanced both the stress tolerance and nitrogen-fixing abilities of the strains. Furthermore, the inoculation of otsA-overexpressing recombinant cells leads to greater agronomic traits in the host plant’s peanuts under salinity conditions. We hope our findings may serve as valuable references for the future development of efficient and superior engineered rhizobial strains for peanut cultivation.
... BNF has been reported as one of the principal sources of N for crop production, as well as organic resources being recycled within the cropping field (Dakora et al., 2015;Mohammed et al., 2018;Kebede, 2021) or concentrated from a larger area, and mineral N fertilizers (Van Groenigen et al., 2015). Of these sources of N, mineral fertilizers have raised a global environmental concern resulting from the large amounts of N entering the global food production system (Van Groenigen et al., 2015;Nyoki and Ndakidemi, 2018). ...
... The increased nitrogen fixation in Rhizobium inoculated plots is an indication of effective legume-microbes symbiosis in which legumes serve as sources of carbon to the bacteria and in turn the bacteria fix atmospheric nitrogen for the host plant through symbiosis. Similar to our findings, several studies have reported an increase in nitrogen fixation following Rhizobium inoculation in legumes (Gyogluu et al., 2016;Mohammed et al., 2018;Ngwenya et al., 2024). Phosphorus and potassium markedly enhanced BNF in this study relative to unfertilized treatments. ...
... In general, grain legumes inoculated with effective rhizobial strains exhibit higher photosynthetic rates, increased chlorophyll levels, and improved plant growth. For example, studies of Bambara groundnut, Kersting's groundnut, and cowpea in Ghana, South Africa, and Eswatini have shown that, by enhancing N 2 fixation, rhizobia boost photosynthetic functioning, leading to higher grain yields [5,13,45] (Figure 2). The role of rhizobia in enhancing photosynthesis highlights the importance of this symbiotic relationship in sustainable agriculture. ...
The interplay between soil rhizobial bacteria and leguminous plants, particularly in Africa, has a profound impact on photosynthetic efficiency and overall crop productivity. This review explores the critical role of rhizobia in enhancing photosynthesis through nitrogen fixation, a process crucial for sustainable agriculture. Rhizobial bacteria residing in root nodules provide legumes with symbiotic nitrogen that significantly boosts plant growth and photosynthetic capacity. Recent advances in molecular genomics have elucidated the genetic frameworks underlying this symbiosis, identifying key genes involved in root nodule formation and nitrogen fixation. Comparative genomics of Bradyrhizobium species have revealed seven distinct lineages, with diverse traits linked to nodulation, nitrogen fixation, and photosynthesis. Field studies across Africa demonstrate that rhizobial inoculation can markedly increase nodulation, nitrogen fixation, and grain yields, though outcomes vary depending on local soil conditions and legume species. Notable findings include enhanced nutrient uptake and photosynthetic rates in inoculated legumes compared with nitrate-fed plants. This review highlights the potential of utilizing indigenous rhizobia to improve photosynthesis and crop resilience. Future prospects involve leveraging genomic insights to optimize rhizobial inoculants and enhance legume productivity in water-limited environments. As climate change intensifies, integrating these advancements into agricultural practices could play a crucial role in improving food security and sustainable soil health in Africa.
... However, their wider adoption and use would require formulation into bioinoculants containing bacteria, fungi, or their combination that can function synergistically to improve plant growth and increase grain yield [4] (Tables 2 and 3). N 2 -fixing rhizobia either formulated alone or in combination with other beneficial rhizobacteria and endophytes are reported to stimulate plant growth and increase yields under field conditions [10,[95][96][97]. In Africa, where most soils are inherently low in mineral nutrients, especially N, inoculating cowpea with Bradyrhizobium strains markedly increased grain yield in Ghana and Mozambique [98]. ...
... With rhizobial inoculants for example, the presence of large populations of ineffective but highly competitive native strains can cause the failure of highly effective inoculant strains to nodulate the host plant [123]. This challenge is compounded by the fact that, even in the same environment, inoculation response can vary with legume genotype [96]. For example, despite the known plant growth-promoting effect of Azospirillum sp., its coinoculation failed to increase soybean yields in Mozambican soils, prompting the need for further research to harness the benefits of these plant-bacterial interactions in changing environments [11]. ...
Microbes such as bacteria and fungi play important roles in nutrient cycling in soils, often leading to the bioavailability of metabolically important mineral elements such as nitrogen (N), phosphorus (P), iron (Fe), and zinc (Zn). Examples of microbes with beneficial traits for plant growth promotion include mycorrhizal fungi, associative diazotrophs, and the N2-fixing rhizobia belonging to the α, β and γ class of Proteobacteria. Mycorrhizal fungi generally contribute to increasing the surface area of soil-root interface for optimum nutrient uptake by plants. However, when transformed into bacteroids inside root nodules, rhizobia also convert N2 gas in air into ammonia for use by the bacteria and their host plant. Thus, nodulated legumes can meet a high proportion of their N requirements from N2 fixation. The percentage of legume N derived from atmospheric N2 fixation varies with crop species and genotype, with reported values ranging from 50–97%, 24–67%, 66–86% 27–92%, 50–92%, and 40–75% for soybean (Gycine max), groundnut (Arachis hypogea), mung bean (Vigna radiata), pigeon pea (Cajanus cajan), cowpea (Vigna unguiculata), and Kersting’s groundnut (Macrotyloma geocarpum), respectively. This suggests that N2-fixing legumes require little or no N fertilizer for growth and grain yield when grown under field conditions. Even cereals and other species obtain a substantial proportion of their N nutrition from associative and endophytic N2-fixing bacteria. For example, about 12–33% of maize N requirement can be obtained from their association with Pseudomonas, Hebaspirillum, Azospirillum, and Brevundioronas, while cucumber can obtain 12.9–20.9% from its interaction with Paenebacillus beijingensis BJ-18. Exploiting the plant growth-promoting traits of soil microbes for increased crop productivity without any negative impact on the environment is the basis of green agriculture which is done through the use of biofertilizers. Either alone or in combination with other synergistic rhizobacteria, rhizobia and arbuscular mycorrhizal (AM) fungi have been widely used in agriculture, often increasing crop yields but with occasional failures due to the use of poor-quality inoculants, and wrong application techniques. This review explores the literature regarding the plant growth-promoting traits of soil microbes, and also highlights the bottle-necks in tapping this potential for sustainable agriculture.
... Recently, the microbial community inoculation method has attracted extensive attention (Mohammed et al., 2018;Kari et al., 2019;Chen et al., 2020;Reeve et al., 2023). Inoculation of complex soil communities has been reported to increase soil biodiversity, and significantly affected soil N cycling processes (Calderón et al., 2017). ...
Microbial biomass nitrogen highlights the importance of diverse microbial communities in nutrient cycling and availability.
Complex soil food webs improved soil nutrient availability and soybean growth.
Soil sterilization boosts soybean growth, likely by eliminating soil-borne pathogens and pests.
Soil fertility is one of the key determinants of agricultural productivity. Soil food webs play an important role in driving soil nutrient cycling and plant health. However, it is poorly known how the soil food web composition and complexity affect plant growth and soil fertility. In this study, soil microorganisms and nematodes isolated from two soil types (i.e., calcareous soil and red soil) and two land use types (i.e., corn-soybean cultivation and natural grass-shrubland) were used to sequentially establish four soil micro-food webs (FW1, FW2, FW3, and FW4) with increasing levels of community complexity based on food web complexity. The four micro-food webs were inoculated to sterilized soils which were then planted with soybeans for three months in a pot experiment under ambient environment. The sterilized soil without food web inoculation was employed as control (C) and unsterilized soil with its original food web was also regarded as a treatment (US) in the experiment. The effects of soil micro-food web complexity on soil nutrient and soybean growth were explored. The results showed that soil total nitrogen (TN) and phosphorus (TP), soil microbial biomasses, and plant nitrogen and phosphorus were generally higher in the four food web inoculation treatments than in the control or unsterilized soil. Surprisingly, the original soil food web treatment (i.e., unsterilized soil) had lower soil or soybean nutrient than the no food web treatment (i.e., sterilized soil). In addition, the complexity of inoculated food webs was positively correlated with soil TN, TP, and total potassium (TK). These results suggest that soil micro-food web complexity is an important driver of soil fertility and affects crop growth. Particularly, complex soil micro-food web maintains higher soil fertility and crop growth. This study provides solid evidence of the roles of soil food web in controlling ecosystem services; and the findings could provide a better understanding of the soil food web structure and soil fertility relationships.
... Low yields are common in the tropics, particularly in Ethiopia, due to insufficient symbiotic interactions and subsequent N deficiencies (Samuel, 2013). Bradyrhizobium strains inoculation has been tested under the glasshouse and field conditions and confirmed to improve cowpea growth, symbiosis, and seed yield (Mohammed et al., 2018). Inoculation, has been also reported to increase nodulation and N 2 fixation in other legumes in Ethiopia (Raji et al., 2019;Beyan et al., 2018;Mohammed et al., 2018;Argaw and Akuma, 2015;Stagnari et al., 2017). ...
... Bradyrhizobium strains inoculation has been tested under the glasshouse and field conditions and confirmed to improve cowpea growth, symbiosis, and seed yield (Mohammed et al., 2018). Inoculation, has been also reported to increase nodulation and N 2 fixation in other legumes in Ethiopia (Raji et al., 2019;Beyan et al., 2018;Mohammed et al., 2018;Argaw and Akuma, 2015;Stagnari et al., 2017). Pre-inoculating seeds with elite Bradyrhizobium strains has improved seed yield performance, symbiosis, and shoot dry matter (Argaw and Akuma, 2015;Mohammed et al., 2018). ...
... Inoculation, has been also reported to increase nodulation and N 2 fixation in other legumes in Ethiopia (Raji et al., 2019;Beyan et al., 2018;Mohammed et al., 2018;Argaw and Akuma, 2015;Stagnari et al., 2017). Pre-inoculating seeds with elite Bradyrhizobium strains has improved seed yield performance, symbiosis, and shoot dry matter (Argaw and Akuma, 2015;Mohammed et al., 2018). ...
Because of its excellent ability to fix atmospheric nitrogen, cowpea [Vigna unguiculata (L.) Walp] makes a significant contribution to soil sustainability and productivity in resource-limited tropical regions. However, due
to in part to ineffectiveness and limited availability of bio-inoculant, its symbiotic N contribution and yield
remained low in the field. Therefore, this study examined the effect of elite cowpea infecting Bradyrhizobium
strains (CP-24 and CP-37) on shoot biomass and symbiotic nitrogen contributions of four cowpea varieties (Keti,
TVU, Black eye bean, and White wonderer trailing). For this a two-year field experiment was carried out at three
sites using a factorial randomized complete block design with four replications. The natural abundance of the 15N
technique was used to compute the symbiotic N contribution. Bradyrhizobium inoculation led to significantly
higher nodule formation, % Ndfa, amounts of N fixed, and shoot biomass, demonstrating the effectiveness and
ability of the strains to enhance soil fertility. Inoculating cowpea with CP-24 strain increased shoot N content, %
Ndfa and N fixed by 40%, 15%, and 41%, respectively, in comparison to the un-inoculated control. Furthermore,
the inoculant-variety interaction had a significant effect on nodule number, nodule dry weight, and amount of
N fixed, with TVU and White Wonderer trailing in combination with CP-24 exhibiting the most outstanding
performance. There was also a strong positive correlation between biomass accumulation and N fixed, as well as
N fixed and seed yield. Therefore, Bradyrhizobium inoculation on cowpea varieties TVU and White Wonderer
trailing with CP-24 strain is recommended at all three tested sites and similar agro-ecologies for improved
symbiotic N contribution and associated yield advantage of cowpea. This study highlights that the use of elite
and crop-specific Bradyrhizobium strains can boost symbiotic nitrogen contribution, soil fertility, and yield
performance of legumes. Thus, it helps resource-poor farmers who are suffering from rising mineral fertilizer costs
to achieve food security while reducing climate change risks.
... Mohammed et al. [41] also found that SSR sequence analysis revealed significant genetic diversity among landraces with different seed-coat colors in Kersting's groundnut (Macrotyloma geocarpum Harms). However, due to the unavailability of genetic information specific to Kersting's groundnut, cowpea SSR markers were used, and the successful crossgenus transferability of SSRs in that study did not only indicate a practical approach for future studies but also suggested an evolutionary closeness between cowpea and Kersting's groundnut [41]. ...
... Mohammed et al. [41] also found that SSR sequence analysis revealed significant genetic diversity among landraces with different seed-coat colors in Kersting's groundnut (Macrotyloma geocarpum Harms). However, due to the unavailability of genetic information specific to Kersting's groundnut, cowpea SSR markers were used, and the successful crossgenus transferability of SSRs in that study did not only indicate a practical approach for future studies but also suggested an evolutionary closeness between cowpea and Kersting's groundnut [41]. Furthermore, the nodulation of Kersting's groundnut by Bradyrhizobium strain CB756 [6], which also nodulates cowpea and was initially isolated from Macrotyloma africanum Blumenthal and Staples [42], suggested a potential synteny between cowpea and Kersting's groundnut. ...
... Recent studies have, however, highlighted the importance of seed-coat pigmentation in the nodulation and N 2 fixation of native African legumes [6,41,54,55]. Black Bambara groundnut landraces were found to show greater nodulation and symbiotic functioning, as evidenced by the lower values of shoot δ 15 N, higher %N from fixation, and greater amounts of fixed N recorded across all study sites [6]. This superior symbiotic performance of the Black Bambara groundnut landrace over its Red counterpart was attributed to its ability to release higher concentrations of nod-gene-inducing anthocyanidins as compared to the Red and Cream landraces [51][52][53]. ...
Legume–rhizobia symbiosis is the most important plant–microbe interaction in sustainable agriculture due to its ability to provide much needed N in cropping systems. This interaction is mediated by the mutual recognition of signaling molecules from the two partners, namely legumes and rhizobia. In legumes, these molecules are in the form of flavonoids and anthocyanins, which are responsible for the pigmentation of plant organs, such as seeds, flowers, fruits, and even leaves. Seed-coat pigmentation in legumes is a dominant factor influencing gene expression relating to N2 fixation and may be responsible for the different N2-fixing abilities observed among legume genotypes under field conditions in African soils. Common bean, cowpea, Kersting’s groundnut, and Bambara groundnut landraces with black seed-coat color are reported to release higher concentrations of nod-gene-inducing flavonoids and anthocyanins compared with the Red and Cream landraces. Black seed-coat pigmentation is considered a biomarker for enhanced nodulation and N2 fixation in legumes. Cowpea, Bambara groundnut, and Kersting’s bean with differing seed-coat colors are known to attract different soil rhizobia based on PCR-RFLP analysis of bacterial DNA. Even when seeds of the same legume with diverse seed-coat colors were planted together in one hole, the nodulating bradyrhizobia clustered differently in the PCR-RFLP dendrogram. Kersting’s groundnut, Bambara groundnut, and cowpea with differing seed-coat colors were selectively nodulated by different bradyrhizobial species. The 16S rRNA amplicon sequencing also found significant selective influences of seed-coat pigmentation on microbial community structure in the rhizosphere of five Kersting’s groundnut landraces. Seed-coat color therefore plays a dominant role in the selection of the bacterial partner in the legume–rhizobia symbiosis.
... In another study involving Kersting's groundnut (Macrotyloma geocarpum Harms), which is a neglected, underutilized, and endangered food and medicinal legume in Africa, analysis of SSR sequences revealed significant genetic diversity among the Kersting's groundnut landraces with diverse seed coat colors [45]. Due to the unavailability of genetic information specific to Kersting's groundnut, Mohammed et al [45] employed SSR markers derived from cowpea. ...
... In another study involving Kersting's groundnut (Macrotyloma geocarpum Harms), which is a neglected, underutilized, and endangered food and medicinal legume in Africa, analysis of SSR sequences revealed significant genetic diversity among the Kersting's groundnut landraces with diverse seed coat colors [45]. Due to the unavailability of genetic information specific to Kersting's groundnut, Mohammed et al [45] employed SSR markers derived from cowpea. The successful cross- 5 genus transferability of SSRs in that study did not only indicate a practical approach for future studies, but also suggested an evolutionary closeness between cowpea and Kersting's groundnut. ...
... The importance of seed coat pigmentation in the nodulation of legumes has been reported before [6,15,17,21,47,48] (see Figure 1), and apparently the variation in seed coat color may be responsible for the different N2-fixing abilities observed among legume genotypes under field conditions in African soils [6,45,47]. The efficiency of N2 fixation in plants could be intricately linked to seed coat pigmentation. ...
The legume-rhizobia symbiosis is one of the most important plant-microbe interactions in sustainable agriculture due to its ability to provide much needed N to cropping systems. This interaction is mediated by the mutual recognition of signaling molecules from the two partners, namely legumes and rhizobia. With legumes, these molecules are in the form of flavonoids and anthocyanins, which are responsible for the pigmentation of plants parts, such as seeds, flowers, fruits and even leaves. Seed coat pigmentation in legumes is a dominant factor influencing gene expression relating to N2 fixation, and may be responsible for the different N2-fixing abilities observed among legume genotypes under field conditions in African soils. Cowpea, Kersting’s bean and Bambara groundnut landraces with black seed coat color are reported to release higher concentrations of nod-gene-inducing flavonoids and anthocyanins when compared to the Red and Cream landraces, hence the black seed coat pigmentation is considered a biomarker for enhanced nodulation and N2 fixation. Cowpea, Bambara groundnut and Kersting’s bean with differing seed coat colors are known to attract different native soil rhizobia, confirmable by PCR-RFLP analysis of bacterial DNA from root nodules of these legumes. Even when seeds of the same legume with diverse seed coat colors were planted together in one hole, the nodulating bradyrhizobia clustered differently in the PCR-RFLP dendrograms. In one study, Kersting’s groundnut, Bambara groundnut and cowpea with differing seed coat colors were selectively nodulated by different bradyrhizobial species. Multilocus sequence analysis showed that different Bradyrhizobium species nodulated the Kersting's bean based on seed coat color. Phylogenetic analysis also placed the bradyrhizobial isolates in close proximity to different Bradyrhizobium species such as B. vignae 7-2T, B. subterraneum 58 2-1T, B. kavangense 14-3T, B. liaoningense 2281 (USDA 3622)T, B. yuanmingense LMG 21827T, B. huanghuaihaiense CCBAU 23303T, B. pachyrhizi PAC48T, and a reference type strain of B. elkanii according to seed coat color. Using 16S rDNA amplicon sequencing, we also found significant selective influences of seed coat pigmentation on microbial community structure in the rhizosphere of five Kersting’s groundnut landraces. For example, the rhizosphere of Belane Mottled landrace was dominated by Proteobacteria, while Bacteroidetes dominated the rhizospheres of the other landraces. With legumes, seed coat pigmentation therefore plays a dominant role in the selection of the bacterial symbiotic partner.
... Bambara groundnut is a drought-tolerant legume in sub-Saharan Africa and is well adapted to marginal agricultural lands (Soumare et al., 2022). Kersting groundnut (Macrotyloma geocarpum) is also a neglected and endangered food legume in Africa (Mohammed et al., 2018). Another species of wild legume adapted to the semi-arid conditions of southern Africa is the marama bean (Tylosema esculentum). ...
O Cordyceps militaris (C. militaris) desperta interesse devido a sua capacidade de reprodução em ambiente controlado. Estudos anteriores demonstraram que seus componentes são comparáveis aos encontrados na natureza, contendo diversos compostos bioativos como nucleosídeos, polissacarídeos, ácido γ-aminobutírico (GABA) e ergotioneína. A cordicepina, um nucleosídeo presente no C. militaris, possui atividades imunoestimulantes e antitumorais. A pesquisa foi realizada com a cepa Mound 4#4 bx6 #9 em um meio de cultura composto por extrato de malte, peptona de soja, sulfato de magnésio, citrato de amônio, fosfato de potássio monobásico e arroz. Os frascos inoculados foram mantidos sob condições controladas até a frutificação do fungo. Observamos que a luz teve um papel importante na pigmentação e morfologia das colônias, com maior pigmentação observada sob iluminação. O tempo de incubação também afetou a pigmentação, com aumento progressivo em algumas colônias. Concluímos que o cultivo de C. militaris é viável em condições controladas, com a luz e o substrato exercendo influência significativa na pigmentação e morfologia do fungo. Esses resultados contribuem para o avanço no entendimento do cultivo deste fungo e suas possíveis aplicações biomédicas.
... M. geocarpum is a versatile plant used for food, feed, and medicine [292]. The seeds are used in a variety of diets; they are boiled, seasoned with salt and vegetable oil, and consumed either singly or alongside other carbohydrates [293]. ...
... The seeds are used in a variety of diets; they are boiled, seasoned with salt and vegetable oil, and consumed either singly or alongside other carbohydrates [293]. The flour from the seeds is used to make porridge, various local cakes (Ata, Akara), bean cakes (Koose), and boiled pastes (Tubani) [292]. As a weaning food for infants, a 70:30 mixture of flour and maize flour can be used because it has higher amino acid and mineral content than ordinary maize flour [286]. ...
... Traditionally, the water in which the seeds are boiled is consumed as a treatment for diarrhoea while the powdered seed and water or "pito", consumed as a local beer in Ghana is used as an emetic [292]. The plant is used to treat diabetes, fever, dysentery, and venereal diseases, and a vermifuge is made from the leaf decoction [295]. ...
Legumes are a major food crop in many developing nations. However, orphan or underutilized legumes are domesticated legumes that have valuable properties but are less significant than main legumes due to use and supply restrictions. Compared to other major legumes, they are better suited to harsh soil and climate conditions, and their great tolerance to abiotic environmental circumstances like drought can help to lessen the strains brought on by climate change. Despite this, their economic significance in international markets is relatively minimal. This article is aimed at carrying out a comprehensive review of the nutritional and pharmacological benefits of orphan legumes from eight genera in the sub-family Faboidea, namely Psophocarpus Neck. ex DC., Tylosema (Schweinf.) Torre Hillc., Vigna Savi., Vicia L., Baphia Afzel. ex G. Lodd., Mucuna Adans, Indigofera L. and Macrotyloma (Wight & Arn.) Verdc, and the phytoconstituents that have been isolated and characterized from these plants. A literature search was conducted using PubMed, Google Scholar, and Science Direct for articles that have previously reported the relevance of underutilized legumes. The International Union for Conservation of Nature (IUCN) red list of threatened species was also conducted for the status of the species. References were scrutinized and citation searches were performed on the study. The review showed that many underutilized legumes have a lot of untapped potential in terms of their nutritional and pharmacological activities. The phytoconstituents from plants in the subfamily Faboideae could serve as lead compounds for drug discovery for the treatment of a variety of disorders, indicating the need to explore these plant species.
