Identifying Molecular Functions of Heliotropic Motor Tissue Through Proteomic Analysis of Soybean Pulvini

Abstract

Heliotropic and nyctinastic leaf movement are mediated in soybean through turgor changes in the motor cells of the pulvinus, located at the base of the leaves. While some elements of the signaling pathways have been studied, a broad-scale protein identification has not yet been reported. In my research pulvini proteins were extracted in light- and dark-harvested soybean using the TCA/acetone method and identified by LC-MS/MS. Gene ontology analysis revealed proteins involved in proton transport were enriched in the soybean pulvinus proteome compared to a background soybean proteome. Proteins more highly expressed in the light were mostly stress response proteins, while under-expressed proteins were categorized as energy proteins. Further investigations using more sensitive extraction protocols and a multitude of sample times will build on these initial results to provide a thorough examination of heliotropic mechanisms at the molecular level.