Phosphorylation Analysis of the Embryo in Germinating Maize Seed

Abstract

Protein phosphorylation reactions are an integral part of the regulation of enzymatic activity in diverse biological systems. Relatively little is currently known about such regulatory control mechanisms occurring during plant seed germination. In the present study there is reported a total of 197 protein phosphorylation sites in 144 proteins identified in the embryo of germinating Maize using LC‐MS/MS following phosphoprotein enrichment on passage through a strong cation exchange resin column. Using a shotgun technique a total of 1,700 unique proteins were successfully identified. This included: 90 protein kinases (through searching in Maize and Rice databases and 27 phosphatases (through searching in the same two databases). The transcript level of the protein kinases and phosphatases were assayed with quantitative real time PCR at different time points (including dry seeds, 24 hrs. after seed imbibition and during seed germination. 14 protein kinases and 5 phosphatases were found to be dramatically increased during this period, suggesting these enzymes in phosphorylated form must be involved in the regulation of seed germination processes. Supported by a governmental research grant to Northeast Forestry University, Harbin, Heilongjiang, PR China.