|PhD||University of Texas||Austin, Texas||Plant Biology|
Research description: Protein phosphorylation and dephosphorylation play important signaling roles in plant response to environmental stimuli. Extensive recent research in yeast and animals demonstrated that mitogen-activated protein kinase (MAPK) cascades are major pathways that transduce extracellular stimuli, including various stresses, into cellular responses. MAPK is activated by dual phosphorylation of threonine and tyrosine residues in a TXY motif located between subdomains VII and VIII of the kinase catalytic domain by MAPK kinase (MAPKK). MAPKK is, in turn, activated by MAPKK kinase (MAPKKK). Multiple MAPK cascades that carry out different functions are present in a single cell.
SIPK and WIPK, two members of the tobacco MAPK family are activated differentially by various stresses, including wounding and pathogen infection. The primary goal of this lab is to define the in vivo function of these two MAPKs by using a combination of biochemical, molecular and genetic approaches. While the components of a plant MAPK cascade are very similar to those of yeast and mammals, plant MAPKs adopt different function and regulation during the evolution. For instance, elevation of WIPK activity in pathogen-infected cells requires both post-translational phosphorylation and a preceding gene transcription and de novo synthesis of WIPK protein. In contrast, all yeast and mammalian MAPKs pre-exist in cells and require only phosphorylation activation. Very interestingly, induction of WIPK mRNA and protein also occur systemically and correlates with the establishment of systemic acquired resistance (SAR).
By understanding, at molecular and cellular levels, how plants protect themselves under adverse environmental conditions, such as a pathogen attack, we could eventually identify suitable targets for genetically engineering of crops with enhanced disease resistance.
Meng, X. and Zhang, S. (2013). MAPK cascades in plant disease resistance signaling. Annu. Rev. Phytopathol. in press.
Meng, X., Wang, H., He, Y., Liu, Y., Walker, J.C., Torii, K.U., and Zhang, S. (2012). A MAPK cascade downstream of ERECTA receptor-like protein kinase regulates Arabidopsis inflorescence architecture by promoting localized cell proliferation. Plant Cell online doi:10.1105/tpc.112.104695
Li, G., Meng, X., Wang, R., Mao, G., Han, L., Liu, Y., and Zhang, S. (2012). Dual-level regulation of ACC synthase activity by MPK3/MPK6 cascade and its downstream WRKY transcription factor during ethylene induction in Arabidopsis. PLoS Genet. 8: e1002767.
Wang, M., Liu, X., Chen, Y., Xu, X., Yu, B., Glawischnig, E., Zhang, S., Li, Q., and He, Z. (2012) Arabidopsis acetyl-amido synthetase GH3.5 involvement in camalexin biosynthesis through conjugation of indole-3-carboxylic acid and cysteine and upregulation of camalexin biosynthesis genes. J. Integr. Plant Biol. 54: 471–485.
Mao, G., Meng, X., Liu, Y., Zheng, Z., Chen, Z., and Zhang, S. (2011) Phosphorylation of a WRKY transcription factor by two pathogen-responsive MAPKs drives phytoalexin biosynthesis in Arabidopsis. Plant Cell 23: 1639-1653.
Mao, G., Wang, R., Guan, Y.F., Liu, Y., and Zhang, S. (2011) Sulfurtransferase 1 plays essential roles in embryo and seed development in Arabidopsis thaliana. J. Biol. Chem. 286, 7548-7557.
Han, L., Li, G.-J., Yang, K.-Y., Mao. G., Wang, R., Liu, Y., and Zhang, S. (2010) Arabidopsis mitogen-activated protein kinase cascade in regulating Botrytis cinerea-induced ethylene production. Plant J. 64: 114–127
An, F., Zhao, Q., Ji, Y., Li, W., Jiang, Z., Yu, X., Zhang, C., Han, Y., He, W., Liu, Y., Zhang, S., Ecker, J.R., and Guo, H. (2010) Ethylene-induced stabilization of ETHYLENE INSENSITIVE3 and EIN3-LIKE1 is mediated by proteasomal degradation of EIN3 binding F-box 1 and 2 that requires EIN2 in Arabidopsis. Plant Cell 22: 2384–2401.
Jang, E.-K., Min, K.-H., Kim, S.-H., Nam, S.-H., Zhang, S., Kim, Y.C., Cho, K.H., and Yang, K.-Y. (2009) Mitogen-activated protein kinase cascade in the signaling for polyamine biosynthesis in tobacco. Plant Cell Physiol. 50: 658–664.
Beckers, G.J.M., Jaskiewicz, M., Liu, Y., Underwood, W.R., He, S.Y., Zhang, S., and Conrath, U. (2009) MAP kinases 3 and 6 are required for priming of stress responses in Arabidopsis. Plant Cell 21: 944-953.
Cho, S.K., Larue, C., Chevalier, D., Wang, H., Jinn, T.-L., Zhang, S., and Walker, J.C. (2008) Regulation of floral organ abscission in Arabidopsis thaliana. Proc. Natl. Acad. Sci. USA 105:15629-15634.
Ren, D., Liu, Y., Yang, K.-Y., Han, L., Mao, G., Glazebrook, J., and Zhang, S. (2008) Fungal-responsive mitogen-activated protein kinase cascade in signaling phytoalexin biosynthesis in Arabidopsis. Proc. Natl. Acad. Sci. USA 105: 5638–5643.
Wang, W., Liu, Y., Bruffett, K., Lee, J., Hause, G., Walker, J.C., and Zhang, S. (2008) Haplo-insufficiency of MPK3 in MPK6 mutant background uncovers a novel function of these two MAPKs in Arabidopsis ovule development. Plant Cell 20: 602–613.
Hord, C.L.H., Sun, Y., Pillitteri, L.J., Torii, K.U., Wang, H., Zhang, S., and Ma H. (2008) The mitogen-activated protein kinases, MPK3 and MPK6, and the ERECTA and related receptor-like kinases are important for Arabidopsis anther development. Mol. Plant 1:645-658.
Zhang, S. (2008) Mitogen-activated protein kinase cascades in plant intracellular signaling. In Annual Plant Reviews, Volume 33: Intracellular Signaling in Plants, edited by Z. Yang. Oxford: Wiley-Blackwell. (ISBN: 9781405160025).
Joo, S., Liu, Y., Lueth, A., and Zhang, S. (2008) MAPK phosphorylation-induced stabilization of ACS6 protein is mediated by non-catalytic C-terminal domain, which also contains the cis-determinant for rapid degradation by the 26S proteasome pathway. Plant J. 54: 129–140.
Underwood, W., Zhang, S., and He, S.-Y. (2007) The Pseudomonas syringae type III effector tyrosine phosphatase HopAO1 suppresses innate immunity in Arabidopsis thaliana. Plant J. 52: 658–672.
Liu, Y., Ren, D., Pike, S., Pallardy, S., Gassmann, W., and Zhang, S. (2007) Chloroplast-generated reactive oxygen species are involved in hypersensitive response-like cell death mediated by a mitogen-activated protein kinase cascade. Plant J. 51: 941–954.
Wang, H., Ngwenyama, N., Liu, Y., Walker, J.C., and Zhang, S. (2007) Stomatal development and patterning are regulated by environmentally responsive mitogen-activated protein kinases in Arabidopsis. Plant Cell 19: 63–73.
Mino, M., Kubota, M., Nogi, T., Zhang, S., and Inoue, M. (2007) Hybrid lethality in interspecific Nicotiana gossei x N. tabacum involves a MAP-kinases signalling cascade. Plant Biol. 9: 366–373.
Suarez-Rodriguez, M.C., Adams-Phillips, L., Liu, Y., Wang, H., Su, S.-H., Jester, P.J., Zhang, S., Bent, A.F., and Krysan, P.J. (2007) MEKK1 is required for flg22-induced MPK4 activation in Arabidopsis plants. Plant Physiol. 143: 661–669.
Research areas: MAP kinases and signaling in plant defense responses.
How to apply:
Electronic submission is encouraged, e-mail to firstname.lastname@example.org
Applicants should send CV and names of two references to:
Dr. Shuqun Zhang
Christopher S. Bond Life Sciences Center
371G Bond Life Sciences Center
University of Missouri
Columbia, MO 65211