Stephan Winter

Publications (6)11.25 Total impact

• Article: A novel mitovirus from the hypogeous ectomycorrhizal fungus Tuber excavatum.

  J Benjamin Stielow, Zoltan Bratek, Hans-Peter Klenk, Stephan Winter, Wulf Menzel
  Archives of Virology 01/2012; · 2.11 Impact Factor
• Article: Analysis of the tomato mild mottle virus genome indicates that it is the most divergent member of the genus Ipomovirus (family Potyviridae).

  Adane Abraham, Wulf Menzel, H Josef Vetten, Stephan Winter
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  ABSTRACT: The complete genome of a tomato mild mottle virus (ToMMV) isolate was analysed, and some biological features were characterized. The ssRNA genome of ToMMV from Ethiopia encompasses 9283 nucleotides (excluding the 3' poly(A) tail) and encodes a polyprotein of 3011 amino acids. Phylogenetic and pairwise comparisons with other members of the family Potyviridae revealed that ToMMV is the most divergent member of the genus Ipomovirus, with a genome organization similar to that of members of the species Sweet potato mild mottle virus, the type species of the genus. In contrast to earlier reports, ToMMV isolates from Yemen and Ethiopia were not transmitted by the aphid Myzus persicae, but they were transmitted very erratically by the whitefly Bemisia tabaci. A comparison of the 3'-proximal sequences of different isolates provided evidence for geographically associated genetic variation.
  Archives of Virology 11/2011; 157(2):353-7. · 2.11 Impact Factor
• Article: Characterization of cucumber vein-clearing virus, a whitefly (Bemisia tabaci G.)-transmitted carlavirus.

  Wulf Menzel, Mathew M Abang, Stephan Winter
  Archives of Virology 09/2011; 156(12):2309-11. · 2.11 Impact Factor
• Article: A novel Tuber aestivum (Vittad.) mitovirus.

  Benjamin Stielow, Hans-Peter Klenk, Stephan Winter, Wulf Menzel
  Archives of Virology 06/2011; 156(6):1107-10. · 2.11 Impact Factor
• Article: Secondary metabolite profile and phytotoxic activity of genetically distinct forms of Colletotrichum gloeosporioides from yam (Dioscorea spp.).

  Mathew M Abang, Wolf-Rainer Abraham, Robert Asiedu, Peter Hoffmann, Gerhard Wolf, Stephan Winter
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  ABSTRACT: Highly virulent, slow-growing grey (SGG); moderately virulent, fast-growing salmon (FGS); and avirulent/weakly virulent, fast-growing grey (FGG) forms of Colletotrichum gloeosporioides have been described from yam (Dioscorea spp.), but little is known about their chemodiversity or the role of toxins in their pathogenesis. Secondary metabolite profiles in high performance tlc (hptlc) showed that the pathogenic SGG and FGS forms have a chemotype (A or B) that is distinct from the non-pathogenic FGG form (chemotype C). Crude extracts of 35-d-old Czapek-Dox yeast broth cultures of FGS and SGG isolates caused tissue necrosis on treated yam leaves but not those of FGG isolates. Extracts from uninoculated broth cultures showed no phytotoxic activity. Toxicity of the culture filtrate was not host specific and toxic substances were thermostable. Dioscorea genotypes with varying levels of resistance to anthracnose differed in their sensitivity to crude toxin extract of FGS (Cg33) and SGG (Cg25) isolates, indicating that these extracts may be useful in evaluating host resistance to anthracnose in vitro. Analysis of two toxin fractions unique to the pathogenic FGS and SGG forms using hlpc, mass spectrometry and nuclear magnetic resonance suggested the presence of a low molecular weight amide peptide. However, possibly due to low yield and the presence of impurities, the chemical structure of the compound(s) could not be fully elucidated.
  Mycological Research 10/2008; 113(Pt 1):130-40. · 2.81 Impact Factor
• Source

  Available from: Asiedu Robert

  Article: Review - Molecular taxonomic, epidemiological and population genetic approaches to understanding yam anthracnose disease

  Mathew M Abang, Stephan Winter, Hodeba D Mignouna, Kim R. Green, Robert Asiedu
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  ABSTRACT: Water yam ( Dioscorea alata L.) is the most widely cultivated yam species globally. The major limitation to the profitable and sustainable production of D. alata is its susceptibility to anthracnose disease. The availability of resistant varieties could potentially form the cornerstone of an integrated management strategy for yam anthracnose; however, anthracnose resistance breeding is hampered by the dearth of knowledge on pathogen identity and diversity. Four forms of Colletotrichum are now known to be associated with foliar anthracnose of yam: the slow-growing grey (SGG), the fast-growing salmon (FGS), the fast-growing olive (FGO), and the fast-growing grey (FGG) forms. The close phylogenetic relationship of the first three forms to reference isolates of Colletotrichum gloeosporioides , and the fact that only strains of these forms have been observed to induce typical anthracnose symptoms on D. alata, recently confirmed that C. gloeosporioides is the causal agent of yam anthracnose disease. The FGG form possibly represents a distinct, endophytic, species as indicated by morphological, biological and molecular criteria. Previous research emphasized epidemiology and control but limited progress was made in understanding yam anthracnose disease based on this classical approach. Molecular approaches have started to unravel the systematics and ecology of Colletotrichum strains associated with yam anthracnose, as well the population biology of C. gloeosporioides on yam. Sexual recombination is a likely mechanism contributing to the high genetic diversity of C. gloeosporioides in yam-based cropping systems. Studies have been initiated to understand the mechanisms that generate genetic variation in C. gloeosporioides, and to gain some insight into the biochemistry of the interactions between the pathogen and yam. Our thesis in this article is that integrating traditional and molecular approaches to understanding C. gloeosporioides systematics, epidemiology and population genetics will lead to a much better understanding of yam anthracnose disease, and thus to the development of effective and sustainable control measures. Research successes and challenges are discussed, as well as their implications for future studies on pathogen evolutionary potential, anthracnose resistance breeding, and the deployment of resistance genes.
  African Journal of Biotechnology (ISSN: 1684-5315) Vol 2 Num 12.