Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 3, 2013
Publication Date: June 25, 2013
Citation: Silva-Sanchez, C., Chen, S., Zhu, N., Li, Q., Chourey, P.S. 2013. Proteomic comparison of basal endosperm in maize miniature1 mutant and its wild-type Mn1. Frontiers in Plant Science. 4:1-16. Interpretive Summary: As the major storage organ of a cereal seed, an endosperm in corn seed is a major contributor of food, feed and biofuel production for man. The basal part of an endosperm is however highly specialized in functions that are believed to be related to nutrition and water acquisition from the mother plant, and our previous genetic studies show that abnormalities in this region lead to small or shriveled seeds at maturity. Thus, this region is critical in seed development. Despite such a pivotal role, very limited data are available on its global gene expression profile to understand its overall function in seed development. This report is a cooperative investigation between scientists from CMAVE, USDA ARS SAA, and the University of Florida, at Gainesville, FL, and is based on recently developed high throughput proteomic technologies. It documents an extremely large number of proteins (approx. a total of 2,500 proteins) in contrast with previously known only a dozen proteins; additionally, comparative analysis between a normal and a single gene miniature seed mutant show altered expression levels of nearly 5% of the total proteins in this region of the endosperm. Many of these proteins are predominantly associated with functions related to nutrient transport, disease resistance, mitochondrial functions, hormone biosynthesis, and signaling activity in the basal endosperm. Future studies are aimed to analyze some of these most abundantly expressed specific genes and proteins to better understand their structure and function to enhance seed size and quality, an ultimate unit of crop productivity.
Technical Abstract: Developing endosperm in maize seed is a major site for biosynthesis and storage of starch and proteins, and of immense economic importance for its role in food, feed and biofuel production. The basal part of endosperm performs a major role in solute, water and nutrition acquisition from mother plant to sustain these functions. The miniature1 (mn1) mutation is a loss-of-function mutation of the Mn1-encoded cell wall invertase that is entirely expressed in the basal endosperm and is essential to many of the above functions. Here we report a comparative proteomic study between Mn1 and mn1 basal endosperm to better understand possible basis of pleiotropic effects on many diverse traits in the mutant. Specifically, we used iTRAQ based quantitative proteomics combined with Gene Ontology classification and the KEGG bioinformatics to conduct functional analysis of the proteomic information. A total of 2518 proteins were identified from soluble and cell wall associated protein fractions, and 131 proteins were differentially expressed in the two genotypes. Based on the gene ontology classification, the main functional groups of proteins that were significantly enriched were those involved in the carbohydrate metabolic and catabolic process, and cell homeostasis. The study constitutes the first proteomic analysis of basal endosperm functions in maize kernel growth and development.