From Proplastid to Chloroplast: Understanding Plastid Differentiation in Maize through Microarray and Proteome Analysis

Cornell Univ - State: Awds Made Prior May 2010, Ithaca NY

Investigators

Abstract

Although best known for their role in photosynthesis, plastids perform several essential functions, which include synthesis of hormones, amino acids, fatty acids, lipids, vitamins, nucleotides and secondary metabolites. Despite their essential role, little is known of the developmental signals that help drive the process of plastid differentiation.. To address this important agricultural and biological problem, we will take advantage of new tools that have been developed for genomic and proteomic studies. The availability of extensive plant genome sequences has enabled us to identify a set of approximately 1500 maize EST sequences that encode chloroplast targeted proteins. Through array profiling, we will examine the expression of these genes in the two photosynthetic cell types in maize, the bundle sheath and mesophyll. In parallel, we will initiate a broad survey of the estimated 3,000 proteins predicted to accumulate in plastids using highly sensitive mass spectroscopy techniques. The bioinformatic integration of proteomic and expression profiling data will provide a detailed picture of transcription and translational control mechanisms utilized by the maize photosynthetic plastids. Finally, transgenic plants carrying bundle sheath and mesophyll cell-specific markers will be constructed to help monitor the differentiation process. These GFP constructs will permit a detailed analysis of bundle sheath and mesophyll cell biology and facilitate the analysis of a series of maize plastid mutants. Several results are expected from this project, such as an improved understanding of the biochemical functions of the different plastid types and novel insights into the differentiation process. As several chloroplast functions are directly related to the agronomic performance of the maize plant, these studies will greatly improve our understanding and ability to engineer this important crop plant.