A notable characteristic of plant physiology is the ability of plants to sense the direction of the gravity vector and use that information to organize their body plan. This ability, known as gravitropism, is the sum result of three distinct processes: stimulus perception, signal transduction, and differential growth. Of the three, little is known about the mechanics of signal transduction. The comparison of gene and protein expression in plants grown both with and without gravity represents a critical step in understanding how the process works. Here we report the development of a protocol for the isolation of protein for iTRAQ analysis from Arabidopsis thaliana seedlings grown under Earth-bound and microgravity conditions. Parameters including seed weight, growth time, and extraction methodology were examined to maximize protein production while simultaneously minimizing the impact of stress responses on our proteomic data. We also optimized a protocol for extended inhibition of seedling germination until samples had arrived aboard the International Space Station. A trial run of the experiment was performed at Kennedy Space Center in Cape Canaveral, FL with the samples proteomic viability validated through the identification of 3,667 proteins using iTRAQ analysis. Furthermore, we report on our investigation into the molecular machinery which establishes the gravity set-point angle (GSA) of lateral roots. 12 day-old gravity mutants (gps5 & zig-1) and their reference ecotypes (Col-0 and WS) were clinorotated ∼8hr The angle with respect to the gravity vector in pre- and post-clinorotated roots was measured at a distance of 2mm from the tip. Our results indicate VTI11, the vesicle soluble NSF attachment protein receptor (v-SNARE) encoded by zig-1, may play a role in the establishment of the GSA of lateral roots.
|Commitee:||Liebl, Faith, Williams, Jake|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 55/01M(E), Masters Abstracts International|
|Keywords:||Gravitropism, Gravity set-point angle, Lateral root gsa, Microgravity, Proteomics|
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