CAREER: Genetic and Proteomic Analyses of MAP Kinase Pathways in Plant Disease Resistance

University Of Missouri-Columbia, Columbia MO

Investigators

Abstract

This CAREER program is designed to integrate research into teaching and to promote the incorporation of biochemical/proteomic methods into molecular/genetic research among students and post-docs. Increasing evidence from biochemical and molecular studies implicated SIPK and WIPK, two tobacco mitogen-activated protein kinases (MAPKs) in plant disease resistance signaling. However, genetic evidence is lacking. Activation of endogenous SIPK and WIPK by expressing the active mutant of their upstream kinase, NtMEK2DD leads to the induction of defense genes and hypersensitive response (HR)-like cell death. The identification of the homologous pathway in Arabidopsis, AtMEK4/AtMEK5-AtMPK6/AtMPK3 permitted genetic screens for modifiers and downstream components of this MAPK pathway, which is one of the major goals of this project. Activation tagging, T-DNA, and EMS mutant populations have been generated in steroid-inducible transgenic Arabidopsis. Mutants that lose cell death phenotype after steroid treatment, MAPK-activation-no-death (mand) will be isolated from T1, T2, or M2 population. Genes responsible for the phenotypic alterations will be cloned, which could be: 1) AtMPK6 and AtMPK3 themselves; 2) the substrate(s) of AtMPK6 and/or AtMPK3; 3) extragenic suppressors and negative regulators of AtMPK6/AtMPK3 pathway such as MAPK phosphatases and scaffold proteins; and 4) other components involved in the regulation and execution of HR cell death. In addition, proteomic approaches will be employed to identify the in vivo substrates of these two MAPKs. The other major goal of this project is to integrate research into classroom teaching and to promote the use of multi-dimensional approach to study a physiological/morphological phenotype, which is critical for the advance of post-genome biology. Undergraduate students, especially those from under represented groups will be actively recruited by participating in institutional programs that reach out to minorities. The concept and techniques of proteomics will be incorporated into the Advanced Biochemistry Laboratory course during the tenure of this program. In an era of significant technological advances, it is important for classroom teaching to absorb these advances and to prepare students with the most updated information. The identification of MAPK substrates and the regulators/executioners of HR would be a significant contribution to the study of plant programmed cell death. One practical extension of this work is that the identification of important regulatory components in plant defense signaling pathway may allow the generation of crops with enhanced disease resistance, which is important for sustaining agricultural production and improving our environment.