Barbara Hohn

Barbara Hohn

Genetic flux in plants

The basis of my career as molecular biologist was laid by work on bacteriophages fd (in Tuebingen and Yale) and lambda (Biocenter, Basel). The studies of morphogenesis of lambda led to in vitro assembly and DNA packaging of this beautiful model virus. This was early times of recombinant DNA and the possibility to make recombinant lambda DNA infectious by packaging it into its preformed capsid was most welcome. As an extension of this work hybrid plasmids containing the phage packaging site cos, later called cosmids were developed. These allowed the cloning of large fragments of DNA and libraries of genomic DNA of many organisms were produced all over the world. However, the most interesting aspect is that of unintended, serendipitous findings applicable for unforeseen uses.

With the move from the Biocenter to the FMI came the move to eukaryotic organisms, specifically plants. In collaboration with plant scientists already located at the FMI studies on transformation of and genetic recombination in plants were conducted. Especially intriguing thereby was to get to know the prokaryotic organism Agrobacterium tumefaciens which has been shown a long time ago to be able to genetically transform (some) plants. The study of the mechanism of transfer of DNA to plants was a fascinating lesson. Again, the naïve and curiosity-driven search for basic principles led to the discovery of the agronomically important grasses such as maize as unforeseen hosts for the bacterium's DNA transfer.

Genomes change over time; an interesting and partially essential contribution to this change is homologous recombination, active as DNA repair pathway in somatic tissue and of critical importance for rearrangement of genes during meiosis. With the help of specially designed marker genes in the transformed model plant Arabidopsis thaliana somatic recombination events could be monitored. These plants allowed the isolation of mutant plants changed in one or the other aspect of the recombination pathway. Especially fascinating was the finding that not only agents acting directly on the DNA but also other environmentally important influences such as pathogen attack led to increases in homologous recombination. Could this be part of evolutionary drive? In a step further, plants treated with UV or a molecule imitating a pathogen provided their untreated progeny with a molecularly undefined, but certainly epigenetically based kind of "memory" of their experience; progeny of treated plants exhibited a higher level of homologous recombination than progeny of untreated plants.

I have been especially privileged to witness big steps in the understanding of the molecular basis of life such as cloning of DNA and later transformation of lower and higher eukaryotic organisms including plants. I am equally privileged for having been able to contribute.

Presently I am enjoying a multifaceted life. I am trying, using collaborations, to further explore the nature of the epigenetic changes mentioned above. I am trying to return the work others have done before to guarantee the infrastructure and quality of scientific institutions (Advisory Boards), to help in evaluations of granting agencies and scientific journals. In addition, I am a consultant of European and international networks. These, as well as the intellectually challenging scientific spirit of the FMI, the unbroken chain of invitations to interesting meetings and other activities keep me very busy.

Kovalchuk I, Kovalchuk O, Arkhipov A, Hohn B (1998) Transgenic plants are sensitive bioindicators of nuclear pollution caused by the Chernobyl accident

Nature Biotechnol 16:1054-1059

Marvin DA, Hohn B (1969) Filamentous bacterial viruses

Bacteriol Rev 33:173

Ries G, Heller W, Puchta H, Sandermann H, Seidlitz HK, Hohn B (2000) Elevated UV-B radiation reduces genome stability in plants

Nature 406:98-101

Hohn B, Hohn Th (1974) Activity of empty, headlike particles for packaging of lambda DNA in vitro

Proc Natl Acad Sci USA 71:2372

Hohn B, Murray K (1977) Packaging recombinant DNA molecules into bacteriophage particles, in vitro

Proc Natl Acad Sci USA 74:3259

Kovalchuk O, Dubrova Y, Arkhipov A, Hohn B, Kovalchuk I (2000) Wheat microsatellite mutation rate after the Chernobyl accident

Nature 407:583-584

Georgopoulos C, Hohn B (1978) Identification of a host protein responsible for bacteriophage morphogenesis (gro E.)

Proc Natl Acad Sci USA 75:131

Lucht J, Mauch-Mani B, Steiner H-Y, Metraux J-P, Ryals J, Hohn B (2002) Pathogen stress increases somatic recombination frequency in Arabidopsis

Nature Genet 30:311-314

Collins J, Hohn B (1978) Cosmids: type of plasmid gene cloning vector that is packageable in vitro in bacteriophage lambda heads

Proc Natl Acad Sci USA 75:4242

Kovalchuk I, Kovalchuk O, Kalck V, Boyko V, Filkowski J, Heinlein M, Hohn B (2003) Pathogen-induced systemic plant signal triggers DNA rearrangements

Nature 423:760-762

Pelczar P, Kalck V, Gomez D, Hohn B (2004) Agrobacterium tumefaciens virulence proteins ViD2 and VirE2 mediate precise integration of synthetic T-DNA complexes in mammalian cells

EMBO Rep 5:632-637

Koukolikova-Nicola Z, Shillito RD, Hohn B, Wang K, Van Montagu M, Zambryski P (1985) Involvement of circular intermediates in the transfer of T-DNA from Agrobacterium tumefaciens to plant cells

Nature 31:191-196

Grimsley N, Hohn T, Davies J, Hohn B (1987) Agrobacterium-mediated delivery of infectious maize streak virus into maize plants

Nature 325:177-179

Fritsch O, Benvenuto G, Bowler C, Molinier J, Hohn B (2004) The INO80 protein controls homologous recombination in Arabidopsis thaliana

Mol Cell (in press)

Schuermann D, Molinier J, Fritsch O, Hohn B (2005) The dual nature of homologous recombination in plants

Trends Genet 21:172-181

Molinier J, Ries G, Zipfel C, Hohn B (2006) Transgenerational memory of stress in plants

Nature 442:1046-1049

Bakkeren G, Koukolikova-Nicola K, Grimsley N, Hohn B (1989) Recovery of Agrobacterium tumefaciens T-DNA molecules from whole plants early after transfer

Cell 57:847-857

Swoboda P, Gal S, Hohn B, Puchta H (1994) Intrachromosomal homologous recombination in whole plants

EMBO J 13:484-489

Schuermann D, Fritsch O, Lucht JM, Hohn B (2009) Replication stress leads to genome instabilities in Arabidopsis DNA polymerase (delta) mutants

Plant Cell 2009 Oct 2 [Epub ahead of print]

PhD students

David Schuermann (2000-2005)
Olivier Fritsch (1998-2004)
Youqiang Wu (1996-2002)
Myriam Duckely (1997-2001)
Natalija Kovalchuk (2001)
Thabani Dube (2000)
Gerhard Ries (1996-1999)
Anna Maria Bravo Angel (1992-1997)
Serge Kocher (1991-1997)
Luca Rossi (1991-1997)
Jesus R. Escudero (1989-1995)
Peter Swoboda (1989-1994)
Elke Jarchow (1987-1991)
Michael Schlaeppi (1986-1991)
Franz Durrenberger (1986-1990)
Guus A.M. Bakkeren (1985-1988)
Didier Schaefer (1986-1988)
Hanes Richter (1984-1987)

Postdoctoral fellows

Lu Liang (2003-2005)
Susan Jacob (2002-2004)
Lisa Valentine (2000-2004)
Pawel Pelczar (1992-2004)
Jean Molinier (2000-2004)
Ortrun Mittelsten Scheid (1992-2003)
Ortrun Mittelsten Scheid (2003)
Olga Kovalchuk (2002)
Bidyut Sarmah (2001-2002)
Istefo Moisyadi (2002)
Viktor Titov (2002)
Valentyna Titova (2002)
Andriy Arkhypov (2001)
Igor Kovalchuk (1997-2001)
Larisa Kovalchuk (2001)
Philippe Crouzet (1995-2000)
Fabrice Dumas (2000)
Olga Kovalchuk (1997-2000)
Jan Martin Lucht (1994-2000)
Seiichi Toki (1997-1999)
Alicja Ziemienowicz (1995-1999)
Nathalie Majeau (1994-1997)
Biserka Relic (1995-1997)
Luca Rossi (1997)
Holger Puchta (1989-1995)
Fabrice Schoumacher (1992-1995)
Bruno Tinland (1991-1995)
Wen Hui Shen (1989-1994)
Kazuhito Akama (1992-1993)
Zdena Nicola-Koukolikova (1985-1992)
Susannah Gal (1989-1991)
Guus A.M. Bakkeren (1988-1990)
Michael Schneider (1988-1990)
Michele Paillard (1985-1987)
Bharat B. Chattoo (1982-1986)
Nigel Grimsley (1984-1986)
Lucia S. Graf (1981-1983)

Technical/Research associates

Razel Arpagaus (2002-2004)
Veronique Kalck (1992-2004)
Monique Thomas-Seldran (2004)
Karin Afsar (1993-2003)
Cynthia Ramos (1985-2003)
Delphine Joly (2000)
Dorothy Mazlum (2000)
Tru-Nghi Emersleben (1993-1994)
Hong Mei (1992-1994)
Karin Afsar (1991-1992)
Andreas Crameri (1984-1990)
Doris Ruegg (1981-1984)


Nicolas Helmstetter (2003-2004)
Marie-Eve Stamm (2003)
Sabine Flury (2000-2003)
Fabian Axthelm (2003)
Divina Gomez Sanles (2002)
Etienne Bucher (1999-2001)
Judith Gallagher (2001)
Maria Aronson (1996)
Klaus Maleck (1994-1995)
Valerie Zahndler (1995)
Karin Blok (1993)
Lecia Ferraz Mazola (1992)
Catherine Zimmermann (1989-1991)
Karin Blok (1987-1988)
Blaine C. Shiff (1986-1987)
Carolyne J. Meduski (1985-1986)
Sigurd Okkels (1984-1986)
Helene Giroux-Bresson (1983-1984)

Visiting scientists

Nigel Grimsley (2003-2004)
Prasanta Das (2004)
Alicja Ziemienowicz (2003)
Stefan Moisyadi (2002)
Sampa Das (2002)
Gordana Cerovic (1992)
Sampa Das (1991)
Celia D. Knight (1989-1990)
Imaculada Ponte (1989-1990)
Urszula Szybiak (1989-1990)
Jose Torne (1988-1990)
Anna Alwen (1988)
Dave Nii Teiko Aryee (1987-1988)
Susannah Gal (1987-1988)
Christine Gietl (1986-1987)
Rolf-Rainer Mendl (1987)
Mihalia Czako (1986)
Thomas Prof. Borner (1985)
Margaret Alison Dunn (1984)
Annick De Framond (1983)
Peter C. Wolk (1982)
John C. Wootton (1980-1981)


PhD in Biochemistry, University of Tübingen, Germany
Study of Chemistry, University of Vienna, Austria

Positions held

Titular Professor, University of Basel
Lecturer for Molecular Genetics in Plants, Basel University
Junior and Senior Group Leader, Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
Postdoctoral fellow, University of Basel, Switzerland
Postdoctoral fellow, University of Stanford, USA
Postdoctoral fellow, University of Yale, USA


Foreign Member of the Royal Society
Member of the Austrian Academy of Sciences
Member of the Scientific Advisory Board and Coordinator of the Indo-Swiss Collaboration in Biotechnology
Member of the Scientific Advisory Board of the Gregor Mendel Institute for Plant Molecular Biology, Vienna, Austria
Advisory Editorial Board of "The EMBO Journal" and "EMBO Reports"
Member of the Scientific Advisory Board of the Institute for Plant Genetics and Crop Plant Research, Gatersleben, Germany
Member of Board of Directors of the International Society for Plant Molecular Biology
Science Prize of the City of Basel
Member of the Swiss National Research Council
Founding Member of Academia Europaea
Member, EMBO
EMBO Lectureship