Poster: Root biology

Abs # 705: Proteomic analysis of the differential responses to water deficit within the maize primary root growth zone

Presenter:	Zhu, Jinming , Zhuj@missouri.edu
Authors	Zhu, Jinming  (A)   Asirvatham, Victor  (B)   Hejlek, Lindsey G (A)   Poroyko, Valeriy  (C)   Wu, Yajun  (D)   Schachtman, Daniel P (B)   Bohnert, Hans J (C)   Nguyen, Henry T (A)   Sharp, Robert E (A)
Affiliations:	(A): Dept. Agronomy, Univ. Missouri, Columbia (B): Donald Danforth Plant Science Center, St. Louis, Missouri (C): Dept. Plant Biology, Univ. Illinois, Urbana-Champaign (D): Dept. Plants, Soils and Biometeorology, Utah State Univ., Logan

Kinematic studies have revealed different responses of cell elongation to water deficit in distinct regions of the growth zone of the maize primary root. In the apical 3 mm region, elongation rates are maintained at well-watered rates under severe water deficit, whereas the region from 3-7 mm from the apex exhibits maximum elongation in well-watered roots, but progressive inhibition of elongation in roots under water deficit. Previous work revealed that cell wall extensibility is increased in response to water deficits in the apical region. Our goal is to gain a comprehensive understanding of how protein composition, in particular cell wall proteins, changes in association with the differential growth responses to water deficits in the different regions. As an initial step, we studied total soluble protein profiles on two-dimensional SDS-PAGE gels, and identified proteins that reproducibly exhibited higher or lower abundance in the water deficit compared to the well-watered treatment by mass spectrometry and protein database analysis. Also, a correlation was found between protein and transcript abundance (determined by analysis of a SAGE library for well-watered maize roots). Protocols for extracting three fractions of cell-wall proteins (water-soluble plus loosely ionically bound, tightly ionically bound, covalently bound) from the different regions of the root growth are being developed, and progress on proteomic analysis of the extracted proteins will be reported. (Supported by the National Science Foundation, Plant Genome Program, DBI-0211842.)