BCH
Maître de Conférences
Activité scientifique
Profil chercheur
Enseignant-chercheur à l’Université de Yaoundé I. Grade : Maître de Conférences.
Publications scientifiques
Vanessa Nya Dinango, H. Dhouib, Lobna Jlail, Slim Tounsi, Fabrice Fekam Boyom, Louise Nana Wakam et 1 autre(s)
Applied Soil Ecology
Lanvin Rochal Kepngop Kouokap, Everlyne N. Wosula, Massoud Amour, P. Guemkam Ghomsi, Louise Nana Wakam, Germain Kansci et 1 autre(s)
Insects
Bemisia tabaci (Gennadius) is as a major pest of vegetable crops in Cameroon. These sap-sucking insects are the main vector of many viruses infecting plants, and several cryptic species have developed resistance against insecticides. Nevertheless, there is very little information about whitefly species on vegetable crops and the endosymbionts that infect them in Cameroon. Here, we investigated the genetic diversity of whiteflies and their frequency of infection by endosymbionts in Cameroon. Ninety-two whitefly samples were collected and characterized using mitochondrial cytochrome oxidase I (mtCOI) markers and Kompetitive Allele Specific PCR (KASP). The analysis of mtCOI sequences of whiteflies indicated the presence of six cryptic species (mitotypes) of Bemisia tabaci, and two distinct clades of Bemisia afer and Trialeurodes vaporariorum. Bemisia tabaci mitotypes identified included: MED on tomato, pepper, okra, and melon; and SSA1-SG1, SSA1-SG2, SSA1-SG5, SSA3, and SSA4 on cassava. The MED mitotype predominated in all regions on the solanaceous crops, suggesting that MED is probably the main phytovirus vector in Cameroonian vegetable cropping systems. The more diverse cassava-colonizing B. tabaci were split into three haplogroups (SNP-based grouping) including SSA-WA, SSA4, and SSA-ECA using KASP genotyping. This is the first time that SSA-ECA has been reported in Cameroon. This haplogroup is predominant in regions currently affected by the severe cassava mosaic virus disease (CMD) and cassava brown streak virus disease (CBSD) pandemics. Three endosymbionts including Arsenophonus, Rickettsia, and Wolbachia were present in female whiteflies tested in this study with varying frequency. Arsenophonus, which has been shown to influence the adaptability of whiteflies, was more frequent in the MED mitotype (75%). Cardinium and Hamiltonella were absent in all whitefly samples. These findings add to the knowledge on the diversity of whiteflies and their associated endosymbionts, which, when combined, influence virus epidemics and responses to whitefly control measures, especially insecticides.
Lanvin Rochal Kepngop Kouokap, Pierre Eke, Vanessa Nya Dinango, Diane Youmbi Yimta, Pierre Gilbert Ghomsi Tamghe, Germain Kansci et 1 autre(s)
Plant
<i>Trichoderma</i> is a ubiquitous fungal genus widely used in agriculture. Their ability to mininize fertiliser dosage, pesticide rationing, and increase crops yield have offered huge avenues for sustainable agriculture. Nonetheless, given the diversity of the world's agro-ecosystems, their widespread adoption has been restricted. This work aimed at investigating the impact of solid formulation of a consortium of two <i>Trichoderma</i> strains, <i>T. atroviridae</i> T2 and <i>T. Harzianum</i> T8, on the growth and yield of hot Pepper under open-field conditions. When compared to un-primed plants, <i>Trichoderma</i>-primed plants boosted Chla, Chlb, Chl (a+b) and Carotenoid by up to 122%, 11%, 113%, and 48%, respectively. Likewise, 108%, 220% and 76% more phosphorus, nitrogen and auxin were accumulated in <i>Trichoderma</i> inoculated tissues, leading to significant increases in almost all agro-morphological parameters, culminating at 23.5%, 54%, and 23.5%, respectively for production yield (PY), fruit diameter (FD), and Pepper fruits weight (PY) as compared to un-inoculated counterparts. There was no difference in specific activities of catalase (CAT) and peroxidase (POX), even though there were increases in phenolic (17%) and total proteins (15%). These findings suggest that <i>Trichoderma</i> fertilisation can redirected plant response depending of plant statue, which prioritised host fitness and associated biomolecules under our experimental settings with the absence/least-biotic stresses.
Vanessa Nya Dinango, Pierre Eke, Diane Youmbi Yimta, Lanvin Rochal Kouokap, Rufin Toghueo Kouipou, Gilbert Ghomsi Tamghe et 3 autre(s)
SSRN Electronic Journal
Vanessa Nya Dinango, Pierre Eke, Diane Yimta Youmbi, Lanvin Rochal Kepngop Kouokap, Rufin Marie Kouipou Toghueo, Gilbert Ghomsi Tamghe et 3 autre(s)
Rhizosphere
Pierre Eke, Aundy Kumar, Kuleshwar Prasad Sahu, Louise Nana Wakam, Neelam Sheoran, Mushineni Ashajyothi et 2 autre(s)
Microbiological Research
Pierre Eke, Vanessa Nya Dinango, Louise Nana Wakam, Rufin Marie Kouipou Toghueo, Lanvin Rochal Kepngop Kouokap, Lile Christelle Nguemnang Mabou et 3 autre(s)
Archives of Phytopathology and Plant Protection
We attempted to detect and assess the pathogenic potentials of the mycoflora causing wilt and root rot in pepper and to screen the antagonistic potentials of two medicinal plant-derived Trichoderma species (Trichoderma atroviride T32 and Trichoderma sp. N97) against the more pathogenic fungal pathogens. The taxonomic characterization revealed that the Fusarium spp. (56.9%), constituted of F. oxysporium f. sp. capsici (47.1%) and F. solani (9.7%) was the most distributed. Axenic soil infestation with the recovered pathogens successfully induced root rot, leaves chlorosis and root rot, resulting in 52% and 68.92% root stunting in sweet and hot pepper, respectively. The bioagents produced up to 64% inhibition of pathogens’ mycelia growth in confrontation assay, presumably by antibiosis. The ethyl acetate-based extracts from the Trichoderma spp. (10 mg/ml) completely lysed the Fusarium conidia and chlamidospores. The tested bioagents are no doubt promising biological control candidates against pepper wilt and root rot pathogens.
Pierre Eke, Adamou Souleymanou, Raymond Fokom, Vanessa Dinango Nya, Patrick Valère Tsouh Fokou, Louise Nana Wakam et 2 autre(s)
Heliyon
The variation in chemical composition of essential oils (EOs) as affected by plant phenology and environmental factors is a crucial limitation in standardization of EOs and thus their effective implementation into novel organic farming. The cultivation of medicinal and aromatic plants (MAP) using bio-elicitors has been advocated as genuine tool to sustainably assure higher quantity and quality EOs. Herein, a field trial and laboratory bioassays were undergone to decipher the impact of a local arbuscular mycorrhizal fungi (AMF) inoculation on agro-morphological yield, EO output and differential suppression of common bean ( Phaseolus vulgaris L.) root rot incited by Fusarium solani. The field experiment was laid out following a completely randomized block design (CRBD) with two treatments; non-inoculated control and AMF-inoculation in triplicates. The effects of the EOs were tested against mycelial growth, conidia and common bean seeds germination. Promising concentrations were thereafter assessed for their suppressive effect against Fusariun solani in planta . A significantly higher collar diameter, hypocotyl branching and subsequent Mycorrhizal Dependency (MD) in mycorrhizal lemongrass [(+)AMF] compared to non-inoculated counterpart [(-)AMF]. The resulting EOs consistently repressed F. solani Fs4 conidia germination and mycelium deployment in a dose-dependent manner, with minimum inhibitory concentration (MIC) of 500 ppm for both the EOs, and 125 ppm for the reference fungicide (Ridomil Plus 44 WP). The EO from mycorrhizal lemongrass protected the common bean plantlets from infection by F. solani Fs4 both in laboratory and greenhouse conditions, leading to healthier and vigorous plantlets. The best protection rate was once more obtained with EO from AMF-primed lemongrass at the concentration of 1000 ppm (65.0%) while the lowest disease severity was obtained with Ridomil Plus 44 WP (63.13%). Overall, AMF inoculation shifted the lemongrass biochemical processes with subsequent impact on growth, and an enhanced suppression in Fusarium root rot under greenhouse conditions.
Pierre Eke, Aundy Kumar, Kuleshwar Prasad Sahu, Louise Nana Wakam, Neelam Sheoran, Mushineni Ashajyothi et 2 autre(s)
Microbiological Research
Pierre Eke, Louise Nana Wakam, Patrick Valère Tsouh Fokou, Therese Virginie Ekounda, Kuleshwar Prasard Sahu, Teddy Hermann Kamdem Wankeu et 1 autre(s)
Rhizosphere
Pierre Eke, Gael Chatue Chatue, Louise Nana Wakam, Rufin Marie Kouipou Toghueo, Patrick Valère Tsouh Fokou, Fabrice Fekam Boyom
Biological Control
Louise Nana Wakam, Alvine Nanhou, Raymond Fokom, Séverin Nguemezi Tchameni, Eddy Ngonkeu, Pierre Eke et 2 autre(s)
Journal of Experimental Agriculture International
International audience
Séverin Nguemezi Tchameni, D. Nwaga, Louise Nana Wakam, Eddy Ngonkeu, Raymond Fokom, Jean Kuaté et 1 autre(s)
Journal of Phytopathology
Abstract The effects of some selected arbuscular mycorrhizal (AM) fungi, Gigaspora margarita and Glomus mossae on the growth and the role of soluble amino acids of two contrasting cocoa cultivars (ICS84 tolerant and SNK10 sensitive) against black pod disease caused by Phytophthora megakarya were investigated. Root colonization by AM fungi is between 50 and 70% 18 weeks after planting. Tested AM fungi significantly increased all the plant growth parameters (height, number of leaves, shoot and root matter) and P uptake as compared to non‐inoculated plants in pot experiments. AM fungi inoculated cocoa reduced the disease severity. Compared to the control, the soluble amino acid levels increased with inoculation of the AM fungi strains in the necrotic stems of disease on inoculated cocoa plants. Significant relationships between amino acids and disease severity observed for two cocoa cultivars imply that the induction of specific amino acids synthesized by leaves, such as arginine, cysteine and glutamic acid, may represent potential candidate molecules for adaptation of such cultivars to P. megakarya disease. Inoculating seedlings with AMF in nurseries could enhance the development of cocoa plants protected against P. megakarya.
R. Fokom, Louise Nana Wakam, Séverin Nguemezi Tchameni, Dieudonné Nwaga
Research Journal of Agriculture and Biological Sciences
N.S. Tchameni, Louise Nana Wakam, A.D. Owona, R. Fokom, Tertulaine Tchana, Joseph Bienvenu Mbarga et 11 autre(s)
Agritrop (Cirad)
Séverin Nguemezi Tchameni, Louise Nana Wakam, Martin Jemo, Raymond Fokom, D. Nwaga
Research Journal of Agriculture and Biological Sciences
1 1 Yaounde, Cameroon. Abstract: Two maize cultivars contrasting on acid stresses, ATP S4.syn Y (acid soil tolerant) and CMS8501 (acid soil sensitive) were grown on aluminium toxic soil with low-P available soil P of southern Cameroon. The objectives were to assess maize cultivar differences for plant growth, P uptake, root colonisation by fungi, and the activity of root phosphatases following inoculation of arbuscular mycorrhizal fungi (AMF). The experiment was conducted in a 2 x 2 factorial arrangements in a complete randomised block design (RBD). The main factor one was the maize varieties (ATP S4.syn Y and CMS8501) and the second factor, the AMF inoculation consisting of four different levels of AMF application: M0 (no AMF inoculation, M1 (Gigaspora margarita inoculation), M2 (Glomus intraradices inoculation), and M3 (the mixture of M1 and M 2). Data were colleted 14, 28, 42 and 63 days after planting. Significant differences (P< 0.05) were observed between the two maize cultivars for shoot growth, P uptake, the percentage of root colonisation by AMF, and the activity of root phosphatases, ATP S4.syn Y the tolerant cultivar for Al toxicity generally exhibited higher values than CMS8501. AMF inoculation significantly increased all the measured plant parameters. Significant relationships between, shoot dry matter and P uptake, and the acid phosphatase activity, respectively observed particularly for ATP S4.syn Y imply that the induction of specific acid phosphatase exuded by roots, and the efficient P remobilisation for biomass production may account as potential candidate mechanisms for adaptation of a such cultivar into acid and low available P soil of southern Cameroon.
Vanessa Nya Dinango, H. Dhouib, Louise Nana Wakam, Lanvin Kepngop Kouokap, Diane Yimta Youmbi, Pierre Eke et 4 autre(s)
Pest Management Science
BACKGROUND: Fusarium maize ear and root rot disease caused by Fusarium verticillioides has become one of the most serious fungal diseases associated with maize production. Due to their abilities to promote plant development and manage diseases, bacterial endophytes provide a more promising approach for treating this vascular disease. RESULTS: This work was undertaken for the selection and identification of promising isolates as plant growth promoters and biocontrol agents against F. verticillioides in maize agroecosystems. A screening procedure consisting of in vitro and in situ tests was applied to 27 endophytic strains originating from desert plants: Euphorbia antiquorum, Calotropis procera, and Alcasia albida. In vitro studies indicated that the bacteria exhibited variable results in biocontrol, endophytism, and plant growth-promoting traits. In addition, in situ plant growth promotion and biocontrol experiments allowed the identification of the most promising bacterial endophytes. In vitro and in situ comparative study results indicated a low correlation. Our data revealed that in situ screening must be used as the method of selection of biocontrol agents against Fusarium ear and root rot disease. Based on in situ results, seven potent strains were selected and identified as Bacillus subtilis, Bacillus velezensis, Bacillus tequilensis, Stenotrophomonas maltophilia, and Klebsiella pneumoniae. CONCLUSION: The results of this study showed that the selected strains seem to be promising candidates to be exploited as biofertilizers and biocontrol agents against Fusarium maize ear and root rot disease. © 2023 Society of Chemical Industry.
Pierre Eke, Vanessa Nya Dinango, Raymond Fokom, Diane Yimta Youmbi, Louise Nana Wakam, Fabrice Fekam Boyom
Lanvin Rochal Kepngop Kouokap, Pierre Eke, Diane Yimta Youmbi, Reymond Fokom, Vanessa Nya Dinango, Louise Nana Wakam
Diane Yimta Youmbi, Pierre Eke, Lanvin Rochal Kepngop Kouokap, Vanessa Nya Dinango, Gilbert Ghomsi Tamghe, Louise Nana Wakam et 1 autre(s)
Egyptian Journal of Biological Pest Control
Abstract Background Bacterial wilt caused by Ralstonia solanacearum (syn. Pseudomonas solanacearum ) is the most devastating bacterial disease of tomato ( Solanum lycopersicum L.) occurring in tropical zones with consequential substantial yield losses in production fields. Currently, microbial technology in cropping systems has directed investigations toward biological control agents (BCAs), emphasizing the use of plant endophytes, including bacteria. The present work aimed to evaluate the potential of endophytic bacteria from Euphorbia antiquorum L. to suppress bacterial wilt incited by R. solanacearum in plants . Results Of the 10 endophytic species screened in vitro for their antagonistic activity, 6 exhibited promising potency with minimum inhibitory concentration (MIC) values ranging from 62.50 to 7.81 µg/ml. These species also produced cell wall-degrading enzymes (amylase, protease and cellulase), ammonia, siderophores, indole acetic acid and salicylic acid. The 3 most potent species ( B. amyloliquefaciens CBa_RA37, B. velezensis CBv_BE1 and B. amyloliquefaciens CBa_BFL2) enhanced the germination of tomato seeds and protected young tomato plantlets from the devastating effects caused by R. solanacearum infection. Conclusions This investigation demonstrated that these endophytic bacteria from E. antiquorum L. endowed with the ability to improve the growth and protection of tomato plants could be further developed as potential biopesticides to help mitigating the effect of bacterial wilt in tomato farms. Further investigation will set the baseline for formulation and evaluation of their efficacy in the open field.
Pierre Eke, Louise Nana Wakam, Raymond Fokom, Therese Virginie Ekounda, Marie-Ampere Bedine Boat, Rodrigue Keumoe et 1 autre(s)
Rhizosphere
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