Supported by National Science Foundation Grant No. 0117260
Establishing the physiological function of 248 Arabidopsis enzymes and proteins presumed to be involved in various networks of phenylpropanoid-acetate metabolism is the goal of this study. There are two main objectives: identifying networks associated with phenylpropanoid coupling/polymerization (e.g. leading to lignins, lignans, suberins, sporopollenins, etc.), including how these enzymes/proteins function. The second objective is to precisely identify the different networks that exist in Arabidopsis that are involved in the conversion of phenylalanine through to the monolignols. In both objectives, functions will be demonstrated in vitro, and we will also establish that this is the true physiological function by demonstrating temporal and spatial correlation with the segments of the metabolic pathway networks involved.
This work will define the organization of the various phenylpropanoid radical-radical coupling and related metabolic processes in Arabidopsis through its entire life cycle. The benefits to the scientific community will include rapid dissemination of results (prior to publication) through a website linked to the Arabidopsis sites, and the provision of research materials (genes, constructs, recombinant proteins, transgenic and mutant plants) as needed. Another important benefit will be the new knowledge gained on these hitherto difficult systems (e.g. coupling/polymerization) involving macromolecular assemblies, and the new insights that will be gained. For enzymes/genes chosen that are ultimately not involved in these pathways, it is considered that metabolite profiling will provide a clue as to function, and this will then be examined also.
Further, in addition to lignification, this study will shed important light on other highly regulated radical-radical phenolic coupling systems in vivo including: the construction of seed coats and metabolites therein; in generating the (strengthened) matrix of trichomes; in forming suberized tissue and in strengthening flower stalks; in biosynthesizing sporopollenin (a remarkably stable component of pollen grains); in reinforcing cutinized tissue; in cross-linking cell wall carbohydrates through hydroxycinnamic acid (phenolic) coupling; and in producing a plethora of defense compounds and presumably for other purposes awaiting discovery.
In addition to peer-reviewed journals, our research findings, information and materials generated by this research will be made available to public databases, updated periodically, by posting data/information on this dedicated website that will be linked up to the Arabidopsis network sites relevant to the project. This information will include: recombinant protein expression vectors constructed by our laboratory; gene identification and gene function analysis; kinetic data results; gene expression profiles; metabolite and lignin analysis; in situ hybridiation data; and light microscopy documentation.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.