Member Institutions:

• Bowling Green State U.
• Cleveland State U.
• Kent State U.
• Medical College of Ohio
• Miami U.
• The Ohio State U.
• Ohio U.
• University of Cincinnati
• University of Toledo
• Wright State U.
• Youngstown State U.

Saskia Hogenhout Assistant Professor Department of Entomology OARDC 1680 Madison Avenue Wooster, Ohio 44691 Phone (330) 263-3730 FAX (330) 263-3686 email hogenhout.1@osu.edu	Back to Scientists

Research Interests

• Molecular basis of interactions between plant pathogens and their insect vectors.
• Microbial endosymbiosis in insects.

Four families of homopterans (aphids, whiteflies, leafhoppers, and delphacid planthoppers), thrips, chrysomellid beetles, and among the acarines, the eriophyd mites, are important vectors of plant viruses and bacteria. More than 380 viruses from 27 plant virus genera are transmitted by the homopterans alone. My research interests aim at understanding the molecular basis of the interactions between plant pathogens and their insect vectors and microbial endosymbiosis in insects. My research program focuses on three themes.

The first subject involves the interaction between the corn stunt spiroplasma (CSS; Spiroplasma kunkelii) and its leafhopper vectors of the genus Dalbulus. Spiroplasmas are members the Class Mollicutes, a group of gram-positive eubacteria, which are characterized by the lack of a cell wall, a small genome size, a low (G + C) content, a small number of rRNA operons, and relative few tRNA genes. Most Spiroplasma species propagate and cause disease in arthropods; only three Spiroplasma species, such as CSS, are transmitted by leafhoppers and are also plant pathogens. The associations of Dalbulus species with S. kunkelii, and Zea species are, from a biological and ecological perspective, better known than any other mollicute/vector/plant host system. The interactions of S. kunkelii with different leafhoppers of the genus Dalbulus vary from efficient vector systems, in which infection with these mollicutes improves the leafhopper's fitness, to inefficient vector systems, in which infection results in a virulent pathogenicity. In this project we expect to provide answers to questions such as how does transmission of mollicutes by insects occur, what are the mechanisms behind virulent and mutualistic beneficial associations, and whether mollicute genes are differently expressed in insects and plants.

The second project focuses on the identification and characterization of leafhopper and viral derived components involved in the transmission of Maize chlorotic dwarf virus (MCDV; genus Waikavirus). MCDV replicates and is restricted to the phloem of maize and requires a protein for transmission by its insect vector, Graminella nigrifons. This protein, called the Helper Component (HC), is solely produced in MCDV-infected plants. HC is suspected to bind to receptor-like structures, in the food canal of leafhoppers thereby forming a matrix to which virus particles attach. Viruses are slowly released from the matrix and, consequently, are transmitted to other plants when leafhoppers move to neighboring plants to feed. We are interested in isolating and characterizing HC. Once the helper component is characterized, the interaction between HC and virus capsid proteins will be studied. In addition, efforts will be made to identify HC-binding structures in the leafhopper food canal.

The third project aims at investigating the nature of the microbial endosymbionts of important homopteran vectors of maize pathogens, such as leafhopper species of the genus Dalbulus, using molecular techniques and microscopy. All homopteran insects harbor phylogenetically diverse bacterial or yeast-like endosymbionts that provide essential nutrients that are missing from the insect phloem diet. Since microbial endosymbionts are essential for the survival of several economically important insect vectors, they could constitute a target for biochemical control.

Selected References

• Hogenhout S.A., Verbeek M., van der Wilk F., Goldbach RW & J.F.J.M. van den Heuvel (2000). Identifying the determinants in the equatorial domain of Buchnera GroEL implicated in binding Potato leafroll virus. In Review.
• Van den Heuvel J.F.J.M., Hogenhout S.A., van der Wilk F. (1999). Recognition and receptors in virus transmission by arthropods. Trends in Microbiology 7: 71-76.
• Van den Heuvel J.F.J.M., Hogenhout S.A., Verbeek M. & F. van der Wilk (1998). Azadirachta indica metabolites interfere with the host-endosymbiont relationship and inhibit the transmission of potato leafroll virus by Myzus persicae. Entomologia Experimentalis et Applicata 86: 260-263.
• Hogenhout S.A., van der Wilk F., Verbeek M., Goldbach R.W. & J.F.J.M. van den Heuvel (1998). Potato leafroll virus binds to the equatorial domain of the aphid endosymbiotic GroEL homolog. Journal of Virology 72: 358-365.
• Van den Heuvel J.F.J.M., Bruyère A., Hogenhout S.A., Ziegler-Graff V., Brault V., Verbeek M., van der Wilk F., & K. Richards (1997). The N-terminal region of the Luteovirus readthrough domain determines virus binding to Buchnera GroEL and is essential for virus persistence in the aphid. Journal of Virology 71: 7258-7265.
• Kamoun S. & Hogenhout S.A. (1997). Results of a five months expedition (1993-94) to study the tiger beetles of Australia (Coleoptera: Cicindelidae). Cicindela 29: 1-18.
• Kamoun S & Hogenhout S.A. (1996). Flightlessness and Rapid Terrestrial Locomotion in Tiger Beetles of the Cicindela L. subgenus Rivacindela van Nidek from Saline Habitats of Australia (Coleoptera: Cicindelidae). The Coleopterists Bulletin 50: 221-230.
• Hogenhout S.A., Verbeek M., Hans F., Houterman P.M., Fortass M., van der Wilk F., Huttinga H. & J.F.J.M. van den Heuvel (1996). Molecular basis of the interaction between luteoviruses and aphids. Agronomie 16: 167-173.
• Karrer E.E., Lincoln J.E., Hogenhout S.A., Bennett A.B., Bostock R.M., Martineau B., Lucas W.J., Gilchrist D.G. & D. Alexander (1994). In situ isolation of mRNA from individual plant cells: creation of cell-specific cDNA libraries. Proceedings of the National Academy of Sciences, USA 92: 3814-3818.
• Overduin B., Hogenhout S.A., van der Biezen E.A., Haring M.A., Nijkamp H.J.J. & J. Hille (1993). The Asc locus for resistance to Alternaria stem canker in tomato does not encode the enzyme aspartate carbamoyltransferase. Molecular and General Genetics 240: 43-48.

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