Thousands of Proteins from Developing Xylem Cells in Poplar Are Identified

The Science

Woody biomass in trees primarily consists of the secondary cell walls of dead xylem tissue, so developing xylem cells are useful models for investigating secondary cell-wall formation. To provide subcellular context for identified protein functions and to enhance the detection of low-abundance proteins, subcellular fractionation techniques were used to obtain crude (soluble protein), pellet (insoluble protein), and nuclear protein fractions for analysis. Applying an automated approach known as MudPIT (Multidimensional Protein Identification Technology), BESC researchers successfully isolated and identified 6,000 different proteins from developing xylem cells in the stems of poplar plants. Results from this project greatly expanded the number of proteins that had been identified in previous poplar proteome studies. The protein products of several cell-wall synthesis genes (e.g., cellulose synthase, sucrose synthase, and polygalacturonase) were found to be associated with cellular membranes, and numerous new candidate genes for cell-wall synthesis were discovered – many are promising targets for further functional genomic analysis. Measuring differences in the whole proteomes of different poplar variations will increase understanding of the fundamental properties that underlie the recalcitrance of woody biomass to degradation.

The Impact

Understanding the molecular pathways of plant cell wall biosynthesis and remodeling is central to interpreting biological mechanisms underlying plant growth and adaptation as well as leveraging that knowledge towards development of improved bioenergy feedstocks.

Principal Investigator

Udaya C. Kalluri
Oak Ridge National Laboratory


Kalluri, U. C., G. B. Hurst, P. K. Lankford, P. Ranjan, and D. Pelletier. 2009. “Shotgun Proteome Profile of Populus Developing Xylem,” Proteomics 9, 4871–80. DOI:10.1002/pmic.200800854.