Cultural, morphological and pathogenic variability of Phytophthora colocasiae isolate from taro in Cameroon

There exist 124 species of Phytophthora worldwide that cause serious diseases in natural ecosystems. These species have been identified using molecular methods. This study was conducted to determine the cultural, morphological and pathogenic variability of isolates of P. colocasiae processed from cultivars of Taro from Cameroon.The study was conducted in three agroecological regions, namely, Yaoundé, Bambui and Ekona where the disease was prevalent. Morphology showed that the mycelia were circular on all the isolates, in the three study zones. Mycelia colours ranged from white to cotton white. The colours of the culture media, after inoculation and mycelia growth, were the same. There was a significant difference (P<0.05) in mycelial growth among the isolate; with the longest of 5.5 cm in V6 juice agar media. Spore morphology was either spherical or ovoid in all the Taro isolates, in all culture media, except water medium. All four isolates were pathogenic to the four cultivars of Taro, causing lesions on leaves on inoculation. The most virulent fungi isolates were L1 (dark green petiole with small leaves) and L2 (red petiole with small leaves), which caused the largest lesion (>10 mm) in Taro cultivars during 14 days of inoculation. &nbsp

Screen house and field resistance of taro cultivars to taro leaf blight disease (Phytophtora colocasiae)

Article PurchasedIntroduction: Taro leaf blight disease cause by Phytophtora colocasiae has become an economic disease in Cocoyam growing regions of Cameroon. Aims: To screen for resistance 10 improved and 4 local cultivars of taro against taro leaf blight disease. Study Design: A randomized complete block design study. Place of Study: Studies were conducted at the International Institute of Tropical Agriculture (IITA) Yaounde Nkolbisson from July 2013 to January 2014. Methodology: Taro cultivars from tissue culture were planted in the screen house conditions and tested for virulence and pathogenicity with 4 isolates of Phythophthora colocasiae at spore density of 3×104 spores /ml of distilled water. Plants were planted in the field to assess disease incidence and severity. Results: The results obtained on the different taro cultivars, revealed that all the 4 isolates showed variable pathogenicity. They caused lesions on inoculated leaves. There was variability in pathogenicity based on the small lesion lengths produced on cultivars, these included BL/SM132 and Red petiole. Isolate 3 showed a stronger sensitivity to leaf collapse and defoliation irrespective of the cultivar tested. There was a significant difference (p = 0.05) in tissue collapse and leaf defoliation on exposure to the different fungal isolates. The result of field infection rates of P. colocasiae at 126 DAP-154 DAP on 10 improved and 4 local cultivars indicated that there was significant variability (p = 0.05) in incidence and disease severity, with high incidence and severity occurring at 154 DAP in all cultivars. Improved cultivar BL/SM132 showed no classic symptoms of P. colocasiae and therefore it was resistant to Phytophthora colocasiae. Conclusion: The results obtained on virulence and pathogenicity of Phythophthora colocasiae on the different taro cultivars revealed that all the 4 isolates showed variable pathogenicity. They caused lesions, on inoculated leaves. Isolate 3 showed a stronger sensitivity to leaf collapse and defoliation irrespective of the cultivar tested. The result of field infection rates of P. colocasiae at 126 DAP-154 DAP on 10 improved and 4 local cultivars indicated that there was a significant variability (p = 0.05) in disease incidence and severity, with high incidence and severity occurring at 154 DAP in all cultivars. Improved cultivar BL/SM132 showed no classic symptoms of P. colocasiae and therefore it was resistant to Phytophthora colocasiae as compared to all the other cultivars which showed high severity rates of infection of the disease and thus were susceptible to the disease

Application of in-vitro micropropagation technique for sustainable production of four local taro cultivars [Colocasia esculenta (L.) Schott] in Cameroon

Open Access JournalTaro leaf blight disease has recently been reported in Cameroon to cause between 50 and 100% yields loss of taro in most of the agro-ecological crop growing regions. This has led to a significant reduction in disease-free planting materials, edible crop and increased. The Meristem culture technique has been used to produce crop plants free of viruses and fungi especially in vegetative propagated colocassia plants. This aimed at applying in-vitro micro-propagation technique for sustainable production of four local taro cultivars in Cameroon. This study was conducted at the Root and Tuber Tissue Culture Laboratory, of the Institute of Agricultural Research for Development (IRAD), Bambui from April 2015 to November 2016. Micro-plants from four local taro cultivars were produced in vitro from apical meristem tips. The tip meristems were excised from corms of the four local taro cultivars. The excised explants were surface sterilized with alcohol and sodium hypochlorite in sequence steps at different concentrations. Meristems were cultured at establishment stage on Murashige and Skoog (MS) medium with 30 g of sugar, 1.1 ml of 6-benzylaminopurine and 7 g of agar. Shoots proliferation was induced in MS with 2.2 ml of 6-benzylaminopurine (BAP). Result shows a significant difference at p≤0.5 in number of shoots, petiole length, open leaf and corm diameter among the cultivars and no significant variation in mean number of senescence leaf with respect to all the cultivars, at 60 days of shoot tip culture. At rooting stage, taro shoots were cultured on MS media supplemented with 10 ml of 0.1 mg/ml naphthalene acetic-acid (NAA). Roots were produced on all the cultivars with excellent mean growth rate of 14.7 ± 0.69 recorded in cultivar with dark green petiole and small leaves

Impact of fungicide application on taro leaf blight disease in three regions of Cameroon

Open Access JournalThe study was conducted in the research field sites of the Institute of Agricultural Research (IRAD), Bambui, North West Region, (IRAD), Ekona South West Region and the International Institute of Tropical Agriculture (IITA) Nkolbisson, Yaoundé, Center Region of Cameroon. Four cultivars of taro (Dark green petiole with small leaves (L1), Red petiole with small leaves (L2), Light green petiole with large leaves (L3) and Light green petiole with small leaves(L4)) were planted in four seasons, for two years, in the months of March and July 2015, March and July 2016 in all the research farms. Ninety corms of the each cultivar were treated before planting with fungiforce at 0.33% concentration while others were not treated. Fungiforce is a contact and systemic fungicide containing high levels of copper oxide (600 grams) and mild levels of metalaxyl (120 grams), various concentrations of 0.4%, 0.33%, 0.27%, at the onset of the first symptom of leaf blight on the leaves using knapsack sprayer of 15 litres at two weeks interval, while the control experiment consisted of unsprayed taro leaves. Data for the disease incidence of taro leaf blight was recorded from the onset of disease in fields and continued at two weeks interval for 6 weeks. The results of planting taro in four seasons in three experimental field sites revealed that there was a decrease in disease incidence in fields sprayed with fungiforce than in the control field. Plots sprayed with fungicide at different concentrations showed no variation on the 4 cultivars in the different field sites. The disease incidence ranged from 10% to 100% in the 4 seasons, at the three experimental field sites. The variation in disease incidence in the three planting sites is an indication of possible genotypes by environment (GXE) interaction that may have significant influence on the taro leaf blight resistance potential

Epidémiologie moléculaire du rotavirus du groupe A associé aux gastroentérites chez les enfants de moins de 5 ans dans la ville de Yaoundé (Cameroun)

Le rotavirus est la première cause de gastroentérites grave chez les enfants de moins de 5 ans. La gravité et la mortalité de la maladie sont majorées dans les pays à revenus faibles d’Asie du sud et d’Afrique subsaharienne. Au Cameroun, la forte prévalence des rotaviroses, associées aux spécificités génotypiques locales du virus, soulignent l’importance de disposer de données épidémiologiques sur le virus. Cette étude visait à contribuer à une meilleure connaissance des principales souches de rotavirus responsables des gastroentérites chez les enfants de moins de 5 ans dans la ville de Yaoundé. Il s’agit d’une étude descriptive transversale d’une durée de 4 mois, dans 8 formations sanitaires de la ville de Yaoundé. Les échantillons de selles d’enfants de moins de 5 ans, hospitalisés pour gastroentérite ont été prélevés. La recherche du rotavirus s’est faite avec le kit ELISA Oxoid ProSpec TTM, et la détermination des génotypes du virus s’est faite par RT - PCR. Cent trente échantillons de selles d’enfants souffrant de gastroentérite ont été collectés. 66,1% de ces échantillons provenaient des hôpitaux FCB/CME, du CHE et de HDE. Le rotavirus a été isolé chez 30% des enfants, dont 40% avait entre 6 et 11 mois. Le CHE (6,9%) et l’HGY (0%) avaient respectivement la prévalence la plus élevée et la plus basse de la ville. Un nombre élevé de combinaisons génotypiques a été isolé, parmi lesquels prédominaient G1P[8] (31%) suivit de G3P[6] (28%) et de G4P[6] (13 %). Les génotypes mixtes G1P[6][8], G2P[6][8], et G1G3P[8] représentaient 22% des isolats. Un type G (3%) est resté indéterminé durant cette étude.© 2015 International Formulae Group. All rights reserved.Mots clés: Epidémiologie moléculaire, rotavirus, génotypes, gastroentérite, enfants, YaoundéEnglish Title:  Molecular epidemiology of group A rotavirus associated to gastroenteritis in children less than 5 years in Yaoundé (Cameroon)English AbstractRotavirus is the leading cause of severe gastroenteritis in children less than 5 years. Severity and mortality of this disease are majored in low-income countries of South - Asia and sub - Saharan Africa. In Cameroon, the high prevalence of rotaviruses associated to local genotypic specificities of virus enhances the importance of epidemiological database on the virus. This study aimed at contributing to a better knowledge of the main rotavirus strains responsible for gastroenteritis in children less than 5 years in Yaoundé. We carried out a descriptive and cross sectional study during 4 months, in 8 health centers in Yaoundé. Stool specimens were collected from children less than 5 years old, hospitalized for gastroenteritis. Rotavirus was detected with ELISA kit Oxoid ProSpecTTM, and genotypes determined by RT - PCR. One hundred and twenty seven stool specimens were collected during the study. FCB/CME, CHE, HDE provided 66.1% of specimens collected. Rotavirus was isolated in 30% of children, and 40% of these children were between 6 to 11 months old. The CHE (6. 9%) and the HGY (0%) had respectively the highest and the lowest prevalence of the town. A large number of genotype has been isolated and G1P[8] (31%) were predominant, followed by G3P[6] (28%) and G4P[6] (13%). Mixt genotypes G1P[6][8], G2P[6][8], and G1G3P[8] represented 22% of isolates. One G - type remained untypable.© 2015 International Formulae Group. All rights reserved.Keywords: Molecular epidemiology, rotavirus, genotypes, gastroenteritis, children, Yaound

Clinical studies on seroprevalence of rubella virus in pregnant women of Cameroon regions.

A study was conducted to investigate the seroprevalence of the rubella virus amongst pregnant women and the relationship it has with the duration of pregnancy, premature delivery, and past history of abortion in pregnant women visiting the Yaoundé Gynecological, Obstetric and Pediatric Hospital (HGOPY). 211 pregnant women attending the prenatal consultation of mean age 27±5.99 years were randomly selected and screened for rubella IgG antibodies. 39.3% of them were in their third trimester of pregnancy while 25.6% and 35.1% were in their first and second trimester of pregnancy respectively. 11.73% of the women had a history of premature delivery and 40.3% had a history of at least one abortion. Spearman's correlation was calculated between antibody titre and age. 88.6% of pregnant women were seropositive while 9% (susceptible) were seronagative and 2.4% had equivocal results. The most susceptible women to rubella infection were in the age group 26-30 years while women in the age group 21-25 years band were the most seropositive. There was a strong correlation between the antibody titre and age (r=0.549

Using weight-for-age for predicting wasted children in Cameroon

Introduction: The equipment for taking body weights (scales) are more frequently used in Cameroon health centres than measuring boards for heights. Even when the later exist there are some difficulties inherent in their qualities; thus the height measurement is not always available or accurate. Our objective for this study was to construct statistical models for predicting wasting from weight-for-age. Methods: 3742 children aged 0 to 59 months were enrolled in a cross-sectional household survey (2004 Cameroon Demographic and Health Surveys (DHS)) covering the entire Cameroon national territory. Results: There were highly significant association between underweight and wasting. For all discriminant statistical methods used, the test error rates (using an independent testing sample) were less than 5%; the Area Under Curve (AUC) using the Receiver Operating Characteristic (ROC) was 0.86. Conclusion: The study showed that weight-for-age can be used for accurately classifying a child whose wasting status is unknown. The result is useful in Cameroon as too often the height measurements may not be feasible, thus the need for estimating wasted children. This study provides baseline information that will help to design a preliminary pivotal study on an immediate nutrition intervention for acute undernutrition. Its complications that could lead to morbidity and mortality can be greatly reduced or set up a management control strategy that will go a long way in reducing the cost of health care in Cameroon.Pan African Medical Journal 2013; 14: 9

Antioxidative properties of Mallotus oppositifolium decoction leaves extract using in vitro models

In an attempt to explain the scientific basis for the medicinal benefits of Mallotus oppositifolium (Euphorbiaceae), the phytochemical constituent and the antioxidative properties of the aqueous decoction leaves extract of the plant versus standard Vitamin C were assessed. The phytochemical analysis (screening and quantitative assay), the 1,1- Diphenyl-2-picrylhydrazyl (DPPH), Nitric oxide, and hydroxyl radicalscavenging, the reducing power, ferrous reducing antioxidant power (FRAP) and the β carotene bleaching of the extract were performed using colorimetric or spectrophotometric methods. Qualitative screening of the extract showed the presence of alkaloids, flavonoids, steroids, phenolic compounds, tannins, phlobatannins, saponins, lipids, carbohydrates, mucilages, and proteins. The phytochemical quantitative assay of the decoction extract revealed that the plant depicted flavonols (38.278 mg.g-1 catechin equivalent), tannins (23.13 mg.g-1 tannic acid equivalent), phenolics (13.73 mg.g-1 tannic acid content), flavonoids (10.62 mg.g-1 quercetin equivalent), proanthocyanidins (2.53 mg.g-1 quercetin equivalent) contents. Alkaloids and saponins content were 200 mg.g-1 and 285 mg.g-1, respectively. The ferric reducing antioxidant power (FRAP) of Mo extract and the IC50 of vitamin C were 228±0.4 mg.mL-1 and 592.0±0.8 mg.mL-1 , respectively. The DPPH radicalscavenging properties of IC50 of vitamin C was 480.0±0.8mg.mL-1 and that of Mo extract was 360.0±0.8 mg.mL-1. The IC50 of Mo’s reduce abilities was 39.2±0.8 mg.mL-1 and that of vitamin C was 320.0±0.8 mg.mL-1.The IC50 of the hydroxyl radical scavenging activity of Mo was 75.2±0,8 mg.mL-1 whereas that of IC50 of vitaminC was not defined. The nitric oxide radical scavenging activity of IC50 of Mo was 121.6±0.8 mg.mL-1 and that of the vitamin C was 130.4±0.8 mg.mL-1, respectively. The β carotene bleanching gives the IC50 of M. oppositifolium was 12,0±0,0 mg.mL-1 and for the vitamin C was 16.0±0,0 mg.mL-1. The decoction leaves of Mallotus oppositifolium (Mo) exhibited powerful antioxidative properties as vitamin C. The plant can be a source of antioxidative materials.Keywords: Traditional medicine, phytochemical analysis, antioxidan