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Articles by O. Traore
Total Records ( 6 ) for O. Traore
  K.D. Adjata , E. Muller , M. Peterschmitt , O. Traore and Y.M.D. Gumedzoe
  Problem statement: This study was carried out to demonstrate that the severity of Cassava Mosaic Disease (CMD) in Togo, is not only influenced by synergism between cassava Begomoviruses in presence, but essentially by recombination between the different Begomoviruses infecting cassava. Approach: Foliar samples presenting typical biological features of Begomoviruses infection were collected from cassava and wild infected plants from different regions of Togo and analysed by PCR targeting the Coat Protein (CP). The PCR products obtained from different isolates of two major Begomoviruses species infecting cassava in Togo were then sequenced and compared with the sequenced of the African cassava mosaic Begomoviruses identified to date and available in NCBI GenBank database by phylogenetic analysis. Results: The results indicate that not only the two major Begomoviruses could be in synergistic interaction in infected cassava in Togo as it has been shown between African Cassava Mosaic Virus (ACMV) and East African Cassava Mosaic Virus (EACMV) elsewhere, but could also create recombinants which would be highly interfering in the development of symptom severity in the country. Conclusion/Recommendations: The study confirmed the assumption that the symptom severity in cassava fields in Togo is rather caused by recombination between different Begomoviruses in presence than by synergistic interaction. More investigations should be done to give insight to this founding.
  R.D.S. Longue , A. Galzi-Pinel , I. Zinga , S. Semballa , D. Fargette , N. Barro and O. Traore
  Background: Rice yellow mottle virus (RYMV) of the genus Sobemovirus is the most important viral disease of rice in Africa, mainly occurring in the lowland and irrigated ecologies. Materials and Methods: The coat protein gene of forty six isolates of RYMV collected between 2011 and 2014 in Central African Republic was amplified and sequenced. Results: Analysis of sequences revealed that the average nucleotide diversity among isolates was low, 2.0% in nucleotide and 0.9% in amino acid. The ratio of non-synonymous over synonymous nucleotide substitutions per site was 0.07, indicating a virus diversification under a high conservative selective pressure. All isolates shared the amino acids specific of the serotype Ser1, a Val115 involved in the response with monoclonal A and a Thr115 which accounts for the lack of reaction with monoclonal D. Phylogenetic analyses showed that isolates of the south of Central African Republic belong to two sister monophyletic groups related to the S1ca strain, a strain which gathers all isolates from the East of West Africa to the West of Central Africa. Molecular clock dating of the age of each of the two groups and of their common ancestor suggests that RYMV was introduced a few decades ago in Central African Republic from the West of Central Africa. Conclusion: RYMV remained at a low level and undetected in wild hosts and in traditional rice fields until recently. RYMV emergence occurred less than ten years ago, likely favored by the on-going rice intensification and resulted in the current epidemics. This is the first study of the molecular diversity of RYMV in Central African Republic. It indicates that the isolates of the South of the country belonged to the S1 strain.
  D. Fargette , A. Pinel , M. Rakotomalala , E. Sangu , O. Traore , D. Sereme , F. Sorho , S. Issaka , E. Hebrard , Y. Sere , Z. Kanyeka and G. Konate
  The rate of evolution of an RNA plant virus has never been estimated using temporally spaced sequence data, by contrast to the information available on an increasing range of animal viruses. Accordingly, the evolution rate of Rice yellow mottle virus (RYMV) was calculated from sequences of the coat protein gene of isolates collected from rice over a 40-year period in different parts of Africa. The evolution rate of RYMV was estimated by pairwise distance linear regression on five phylogeographically defined groups comprising a total of 135 isolates. It was further assessed from 253 isolates collected all over Africa by Bayesian coalescent methods under strict and relaxed molecular clock models and under constant size and skyline population genetic models. Consistent estimates of the evolution rate between 4 x 10–4 and 8 x 10–4 nucleotides (nt)/site/year were obtained whatever method and model were applied. The synonymous evolution rate was between 8 x10–4 and 11 x 10–4 nt/site/year. The overall and synonymous evolution rates of RYMV were within the range of the rates of 50 RNA animal viruses, below the average but above the distribution median. Experimentally, in host change studies, substitutions accumulated at an even higher rate. The results show that an RNA plant virus such as RYMV evolves as rapidly as most RNA animal viruses. Knowledge of the molecular clock of plant viruses provides methods for testing a wide range of biological hypotheses.
  M.D. Traore , V.S.E. Traore , A. Galzi-Pinel , D. Fargette , G. Konate , A.S. Traore and O. Traore
  The roles of guttation fluid, irrigation water, contact between plants and transplantation into contaminated soil in the transmission of Rice yellow mottle virus (RYMV) were assessed. RYMV presence and infectivity were tested by Enzyme-Linked Immunosorbent Assay (ELISA) and by inoculation to susceptible rice cultivar BG90-2. The virus was readily detected in guttation fluid collected from infected rice plants. Transmission tests from this fluid led to high disease incidence (86.6%). Irrigation water collected at the base of infected plants growing in pots was less infectious, as inoculations led to disease incidences below 40%. No virus was detected and could be transmitted from field-irrigation water. Up to 44% healthy rice plants whose leaves were in contact with those of infected plants became infected but, no transmission occurred through intertwined roots. Transplantation of rice seedling into virus-contaminated soil also led to plant infection. However, virus survival in the soil decrease rapidly and infectivity was completely lost 14 days after soil contamination. Altogether, these results indicated that high planting densities of rice are likely to favour secondary spread of rice yellow mottle disease. Transplantation of rice seedlings not earlier than 2 weeks after soil preparation should prevent soil transmission of the virus. Although guttation fluid is highly infectious its contribution to virus infectivity in irrigation water is negligible as field-irrigation water was not found to be an infectious source for RYMV.
  M.D. Allarangaye , O. Traore , E.V.S. Traore , R.J. Millogo , S. Guinko and G. Konate
  In the present study, we investigated on the experimental host range of RYMV among plant species most of which are frequently encountered in rice-growing environments of west and central African savannahs. Only seven out of 66 plant species inoculated were infected by RYMV. All susceptible plant species belonged to the Poaceae family and three of them (Chloris prieuri, Eragrostis cilianensis and Shoenefeldia gracilis) were reported for the first time. Symptoms were conspicuous and persistent in most species but disappeared totally in older plants of some host species such as S. gracilis and Eragrostis tenella. Therefore, surveys for identification of RYMV wild hosts should be conducted before the flowering stage. Virus-host Interactions were studied between 15 RYMV isolates of different strains and 10 wild host species. Differential reactions were obtained in the crow-foot grass Dactyloctenium aegyptium which was susceptible to five of the fifteen isolates. All other plants were susceptible to the whole set of virus isolates. Altogether, this study underlined the narrowness of RYMV host range and pointed out the complexity of interactions between the virus and its hosts, especially the rationale behind overcoming host barriers.
  B.J. Neya , P.E. Zida , D. Sereme , O.S. Lund and O. Traore
  Cowpea (Vigna unguiculata (L.) Walp.) is one the main leguminous crop plants world wide, particularly in sub-Saharan Africa where the rainfall is low and often unevenly distributed. However, its production is limited by insect attacks and numerous diseases including those caused by viruses. In Burkina Faso, the Cowpea Aphid-Borne Mosaic Virus (CABMV) is one of the viruses capable of causing 7-60% of yield losses. The aim of this study is to assess the susceptibility of 21 cowpea varieties against CABMV and to also assess the yield losses caused by this virus on each of the varieties. In this context trial was conducted on INERA research stations at Kamboinsé and Farako-Bâ in 2012 and 2013. Twenty one varieties were used for this study. The experimental design used is a split-plot with 4 repetitions for which the first 2 repetitions were inoculated with the CABMV. Symptoms caused by the CABMV on the 21 varieties of cowpea were of a great diversity. The assessment of the virus in infected plant samples from these varieties by ELISA test allowed detecting the mosaic virus in all samples that presented mosaic symptoms. The number of flowers and pods strongly varied depending to the type of plant (inoculated or non-inoculated plant) and the variety. Yields from the different varieties, comprised between 187 and 6250 kg ha–1, were influenced by the site, the year, the variety and the type of plant. Yields losses were ranged from 3-64% depending to the variety.
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