Hans J. Bohnert. Professor, Departments of Biochemistry and Plant Sciences and Molecular and Cellular Biology. Ph.D., Heidelberg University.
Plant gene expression in response to environmental stress; multigene transfer technology; biochemical pathway engineering in transgenic plants; expression profiling by ESTs and microarrays; sodium long-distance transport.
Chloroplast/cytosol interaction, plastid evolution, plant gene expression in response to environmental stress, enzyme engineering in transgenic plants.

Research in the laboratory is directed towards the dissection of plant metabolism using tools of molecular biology. Areas of emphasis are, at present, (i) the analysis of gene expression responses to environmental stresses, mainly salt stress; (ii) the analysis of promoter elements of environmentally-regulated and developmentally-regulated genes; (iii) plastid-nucleus interaction, and (iv) the study of transgenic plants over-expressing foreign genes.

The common ice plant (Mesembryanthemum crystallinum) has been developed into a model to study environmental stress under aspects of genetics, physiology and biochemistry. The plant has a small genome; its responses to environmental stress (salt, drought, low temperature), and responses to hormones are well defined physiologically (C3 to CAM switching) and biochemically (carbohydrate and proline accumulation); a number of stress-induced genes have been obtained; and morphological markers of stress-enhanced development have been established. Analysis of environmentally induced changes in gene expression progresses at present from the analysis of promoter elements important for the stress-enhanced induction of CAM to the analysis of genes in metabolic pathways not related to CAM.

In the cyanelles of Cyanophora paradoxa a different integration of cytosol and plastid compartments is realized compared to that in higher plants. Cyanelles are as dependent as are chloroplasts on nucleus-encoded transported proteins, however, the cyanelles have retained genes that are nuclear in higher plants, such as nadA (quinolate synthetase), crtE (pre-phytoene pyrophosphate dehydrogenase). Cyanelles also appear to maintain a protein export machinery. Such features make these organelles ideal study objects for studying plastid acquisition, protein translocation and compartmental integration.

DeRocher EJ, Bohnert HJ (1993) Development and environmental stress employ different mechanisms in the expression of a plant gene family. Plant Cell 5:1611-25.

Tarczynski M, RG Jensen, HJ Bohnert (1993) Stress protection of transgenic tobacco by production of the osmolyte mannitol. Science 259:508-10.

Thomas JC, A Smigocki, HJ Bohnert (1995) Light-induced expression of Ipt from Agrobacterium tumefaciens results in cytokinin production and osmotic stress symptoms in transgenic tobacco. Plant Mol. Biol. 27:225-35.

Thomas JC, DG Adams, C Nessler, JK Brown, HJ Bohnert (1995) Reduced whitefly (Besmisia tabaci) reproduction on transgenic tobacco expressing tryptophan decarboxylase. Plant Physiol. 109:in press.

Yamada S, M Katsuhara, W Kelly, CB Michalowski, HJ Bohnert (1995) A family of transcripts encoding MIP-homologues - Tissue specificity of expression under salt stress in Mesembryanthemum crystallinum. Plant Cell 7(8):1129-1142.

Bohnert HJ, D Nelson, RG Jensen (1995) Adaptations to environmental stress. Plant Cell, in press (8/95) 7:1099-1111.

Stirewalt V.L., C.B. Michalowski, W. Loffelhardt, H.J. Bohnert, and D.A. Bryant. Nucleotide Sequence of the Cyanelle Genome from Cyanophora paradoxa. Plant Molecular Biology Reporter vol. 13(4) 1995. pp. 342-347.

J.C. Thomas, D.G. Adams, V.D. Keppenne, C.C. Wasmann, J.K. Brown, M.R. Kanost, and H.J. Bohnert. Manduca sexta encoded protease inhibitors expressed in Nicotiana tabacum provide protection against insects. Plant Physiol. Biochem. 1995, 33(5), 611-614.

G. Rammesmayer, H. Pichorner, P. Adams, R.G. Jensen, and H.J. Bohnert. Characterization of IMT1, myo-Inositol O-methyltransferase, from Mesembryanthemum crystallinum1. Archives of Biochemistry and Biophysics, Vol. 322, No. 1, Sept. 10, pp. 183-188, 1995.