Barbara Baker
Plant innate immunity
Adjunct Professor
Lab Phone: 

Ph.D.  Microbiology and Immunology    UCSF, 1981
B.S.   Biology    UCSD, 1974

The Baker Lab seeks understanding of the molecular, genetic and biochemical bases of host-microbe interactions, and investigates mechanisms of pathogen-induced host disease and disease resistance.

Our goal is to understand the biochemical and molecular bases of plant resistance to pathogen diseases. We especially are interested in understanding the mechanism of plant-pathogen recognition and signal transduction leading to the induction of disease resistance responses. Our experimental system consists of the tobacco mosaic virus (TMV) resistance gene, N, encoding a putative cytoplasmic receptor, disease-resistant plant hosts harboring N, and the classical plant pathogen, TMV.

Plant disease caused by viruses, bacteria and fungi are controlled naturally by plant host resistance (R) genes and avirulence (avr) genes of the pathogen. This has been termed gene-for-gene resistance. A simple model explains these gene-for-gene interactions: Avirulence gene products generate signals (ligands) and resistance genes encode cognate receptors.

We cloned the TMV resistance gene N of tobacco, the first virus resistance gene isolated. Several other R genes encoding resistance to diverse pathogens also were isolated recently from evolutionarily dissimilar plants. Interestingly, the predicted protein products of many of these R genes are similar. They contain domains that explain their possible role in specific pathogen recognition, as well as their role in signal transduction leading to induction of the resistance responses. N and other closely related R genes encode large, putative cytoplasmic proteins that contain a highly conserved nucleotide binding site (NBS) domain and a large leucine rich repeat (LRR) region. The amino-terminal domain of the predicted N product resembles the cytoplasmic domain of the Drosophila Toll protein and the Interleukin-1 receptor (IL-1R) suggesting that N mediates rapid gene induction and TMV resistance through a Toll-IL-1R-like pathway.

We use molecular, genetic and biochemical approaches to elucidate the mechanism of N gene-mediated resistance. Our foci are to discern the role of the putative functional protein domains in pathogen recognition and signal transduction, and to dissect genetically the N-mediated signal transduction pathway. Recently we demonstrated that the N gene of tobacco confers resistance to TMV in transgenic tomato. This is significant for two reasons: first, the transfer of a resistance gene to another species demonstrates the utility of these genes in engineering crop resistance. Second, TMV and other related tobamoviruses can be devastating pathogens of Solanaceous crops, including tomato and pepper. N provides an additional, effective means to combat this disease genetically. Eventually the results of our basic research on R gene function will facilitate development and application of novel strategies for enhanced plant resistance to pathogens for development of disease-resistant crops.

Current projects
  • Interactions between TMV and the tobacco N gene
  • The MAPK Pathway in Tobacco Defense Signaling
  • Study of the Enhanced Disease Susceptibility Gene in Tomato
  • Structural Analysis of Resistance Gene Clusters in Potato
  • Gene Expression Profiling of Tomato Responses to TMV Infection
  • Gene Expression Profiling of Sgt1-silenced N-transgenic Nicotiana Benthamiana
  • Virus-Induced Gene Silencing in Solanum Species


Recent Publications

Hu G.*, deHart A.*, Li Y., Ustach C., Handley V., Navarre R., Hwang C., Aegerter B.J., Williamson V.M. and Baker, B. (2005) EDS1 in tomato is required for resistance mediated by TIR-class R genes and the receptor-like R gene Ve The Plant Journal - download

Huang, S., van der Vossen, E., Kuang, H., Vleeshouwers, V., Zhang, N., Borm, T., van Eck, H., Baker, B., Jacobsen, E. and Visser, R. (2005) Comparative genomics enabled the isolation of the R3a late blight resistance gene in potato The Plant Journal - download

Brigneti, G., Martin-Hernandex, A.M., Jin, H., Chen, J., Baulcombe, D.C., Baker, B. and Jones, J.D.G. (2004) Virus-induced gene silencing in Solanum species The Plant Journal - download

Jin, H., Liu, Y., Yang, K., Kim, C. Y., Baker, B., Zhang, S. (2003) Function of a mitogen-activated protein kinase pathway in N gene-mediated resistance in tobacco The Plant Journal - download

Ronning, C. M., Stegalkina, S. S., Ascenzi, R. A., Bougri, O., Hart, A. L., Utterback, T. R., Vanaken, S. E., Riedmuller, S. B., White, J. A., Cho, J., Pertea, G. M., Lee, Y., Karamycheva, S., Sultana, R., Tsai, J., Quackenbush, J., Griffiths, H. M., Restrepo, S., Smart, C. D., Fry, W. E., Van Der Hoeven, R., Tanksley, S., Zhang, P., Jin, H., Yamamoto, M. L., Baker, B. J., Buell, C. R. (2003) Comparative analyses of potato expressed sequence tag libraries Plant Physiol. - download

Liu, Y., Jin, H., Yang, K., Kim, C. Y., Baker, B. and S. Zhang (2003) Interaction between two mitogen-activated protein kinases during tobacco defense signaling The Plant Journal - download

Schornack, S., Ballvora, A., Gurlebeck, D., Peart, J., Baulcombe, D., Ganal, M., Baker, B., Bonas, U., and Lahaye, T. (2003) The tomato TIR-NB-LRR resistance protein Bs4 discriminates between highly homologous type III-secreted AvrBs3-like effector proteins The Plant Journal - download

Jin, H., Axtell, M. J., Dahlbeck, D., Ekwenna, O., Zhang, S., Staskawicz, B., Baker, B. (2002) NPK1, an MEKK1-like mitogen-activated protein kinase kinase kinase, regulates innate immunity and development in plants Dev. Cell - download

Ballvora, A., Schornak, S., Baker, B., Ganal, M., Bonas, U., and Lahaye, T. (2001) Chromosome Landing at the Tomato Bs4 Locus Mol. Genet. Genomics - download

Dinesh-Kumar, S. P., and Baker, B. (2000) Alternatively Spliced N resistance Gene Transcipts: Their Possible Role in Tobacco Mosaic Virus Resistance Proc. Natl. Acad. Sci. USA - download

Dinesh-Kumar, S. P., and Baker, B. (2000) Structure-Function analysis of the tobacco mosaic virus resistance gene Proc. Natl. Acad. Sci. USA - download

Erickson, L, Holzberg, S., Calderone-Urrea, A., Handley, Y. Axtell, M., Corr, C., and Baker, B. (1999) The Helicase Domain of the TMV Replicase Proteins Induces the N-Mediated Defense Response in Tobacco The Plant Journal - download

Erickson, F. L., Dinesh-Kumar, S. P., Holzberg, S., Ustach, C. V., Dutton, M., Handley, V., Corr, C., and Baker, B. (1999) Interactions Between Tobacco Mosaic Virus and the Tobacco N Gene Phil. Trans. R. Soc. Lond. B - download

Hehl, R., Faurie, R., Hesselback, J., Salamini, F. S., Whitham, S., Baker, B. and C. Gebhardt (1999) TMV resistance gene N homologues are linked to Synchytrium endobioticum resistance in potato Theor. Appl. Genet. - |download

Wirtz, U., Osborne, B., and Baker, B. (1997) Ds Excision from Extrachromosomal Geminivirus Vector DNA is Couples to Cector DNA Replicatoin in Maize The Plant Journal - download

Baker, B., Zambryski, P., Staskawicz, B., and Dinesh-Kumar, S. P. (1997) Recognition and Signaling in Plant-Microbe Interactions Science - download

Whitham, S., McCormick, S., and Baker, B. (1996) The N Gene of Tobacco Confers Resistance to tobacco Mosaic Virus in Transgenic Tomato Proc. Natl. Acad. Sci. - download

Wang, G. L., Warren, R., Innes, R., Osborne., B., Baker, B., and Ronald, P. C. (1996) Construction of an Arabidopsis BAC Library and Isolation of Clones Hybridizing with Disease-Resistance Plant Molecular Biology Report - download

Dinesh-Kumar, S. P., Whitham, S., Choi, D., Hehl, R., Corr, C., and Baker, B. (1995) Transposon Tagging of the Tobacco Mosaic Virus Resistance Gene, N: Its Possible Role in TMV-N Mediated Signal Transduction Pathway Proc. Natl. Acad. Sci. USA - download

Osborne, B. I., Wirtz, U., and Baker, B. (1995) A System for Insertional Mutagenesis and Chromosomal Rearrangement Using the Ds Transposon and Cre-lox Plant Journal - download

Staskawicz, B. J., Ausubel, F. M., Baker, B., Ellis, J. G., and Jones, J. D. G. (1995) Molecular Genetics of Plant Disease Resistance Science - download

Osborne, B., and Baker, B. (1995) Movers and Shakers: Maize Transposons as Tools for Analyzing Other Plant Genomes Current Biology - download

Whitham, S., Dinesh-Kumar, S. P., Choi, D., Hehl, R., Corr, C., and Baker, B. (1994) The Product of the Tobacco Mosaic Virus Resistance Gene N: Similarity to Toll and the Interleukin-1 Receptor Cell - download

Healy, J., Corr, C., DeYoung, J., and Baker, B. (1993) Distribution of Insertion Sites of the Maize Transposon, Ds, in the Tomato Genome Genetics - download

Honma, M., Baker, B., and Waddell, C. (1993) High Frequency Germinal Transposition of Marked Ds in Arabidopsis Proc. Natl. Acad. Sci. USA - download

Osborne, B. I., Corr, C., Prince, J., Tanksley, S. D., McCormick, S., and Baker, B. (1991) Ac Transposition from a T-DNA Can Generate Linked and Unlinked Clusters of Instertions in the Tomato Genome Genetics - download

Hehl, R. and Baker, B. (1990) Properties of the Maize Controlling Element Activator in Transgenic Tobacco Plants: a Versatile Interspecies Genetic Tool The Plant Cell - download

Earp, D., Lowe, B., and Baker, B. (1990) Amplification of Genomic Sequences Flanking Transposable Elements in Host and Heterologous Plants: a Tool for Transposon Tagging and Genome Characterization Nucl. Acids. Res. - download

Laufs, J., Wirtz, U., Kammenn, M., Schaefer, S., Schell, J., Czernilofsky, A, Baker, B., and Gronenborn, B. (1990) Expression and Excision of Transposable Elements Introduced into Various Cereal Cells by a Viral Replicon Proc. Natl. Acad. Sci. USA - download

Hehl, R. and Baker, B. (1989) Induced Transposition of Ds by a Stable Ac in Crosses of Transgenic Tobacco Plants Mol. Gen. Genet. - download

Coupland, G., Baker, B., Schell, J., and Starlinger, P. (1988) Characterization of the Maize Transposable Element Ac by Internal Deletions EMBO J. - download

Baker, B., Coupland, G., Fedoroff, N., Starlinger, P., and Schell, J. (1987) Phenotypic Assay for Excision of the Maize Controlling Element Ac in Tobacco EMBO J. - download

Czernilofsky, A. P., Hain, R., Herrera-Estrella, L., Lorz, H., Goyvaerts, E., Baker, B. J., Schell, J. (1986) Fate of Selectable Maker DNA Integrated into the Genome of Nicotiana tabacum DNA - download

Czernilofsky, A. P., Hain, R., Baker, B., and Wirtz, U. (1986) Studies of the Structure and Functional Organization of Foreign DNA Integrated into the Genome of Nicotiana tabacum DNA - download

Baker, B., Fedoroff, N., Loerz, H., and Schell, J. (1986) Transposition of the Maize Controlling Element Activator in Tobacco Proc. Natl. Acad. Sci. USA - download

Lorz, H., Baker, B., Schell, J. (1985) Gene transfer to cereal cells mediated by protoplast transformation Mol. Gen. Genet. - download

Baker, B., Robinson, H., Varmus, H. E., and Bishop, J. M. (1981) Analysis of Endogenous Avian Retrovirus DNA and RNA: Viral and Cellular Determinants of Retrovirus Gene Expression Virology - download

Spector, D. H., Baker, B., Varmus, H. E., and Bishop, M. J. (1978) Characteristics of Cellular RNA Related to the Transforming Gene of Avian Sarcoma Viruses Cell - download

Friedrich, R., Kung, H. G., Barbara, B., Varmus, H. E., Goodman, H., and Bishop, J. M. (1977) Characterization of DNA Complementary to Nucleotide Sequences at the 5'-Terminus of the Avian Sarcoma Virus Virology - download

Recent Teaching

39C - Freshman/Sophomore Seminar
84 - Sophomore Seminar
170 - Modern Applications of Plant Biotechnology
199 - Supervised Independent Study