Seed germination is a well regulated process, which incorporates a lot of events including signal transduction, reserves mobilization, reactive oxygen species scavenging and cell division.  

Protein phosphorylation/dephosphorylation is one of the most widely known and well-studied posttranslational modification (PTM), which involved in the regulation of seed germination. However, very few studies focused on protein phosphorylation events during germination. 

To better understand the mechanism of seed germination, PhD student HAN Chao, supervised by Prof. YANG Pingfang at Wuhan Botanical Garden, performed a gel-based comparative phosphoproteomic study on rice embryo during germination process.  

Totally, during 168 protein spots exhibited significantly changed Pro-Q staining intensity germination. Using MALDI-TOF/TOF MS analysis, 193 proteins were identified. Combining Pro-Q and Coomassie brilliant blue stain intensity analyses, 109 proteins were verified to be phosphorylation regulation proteins.  

Functional analyses indicated that phosphorylation of proteins involved in stress response and storage was gradually enhanced. Phosphorylation of signal transduction proteins was mainly protein activated during early stage of germination, while stress response and storage phosphorylation were enhanced at the late stage.  

Enzyme assay proved that the phosphorylation of fructokinase, pyruvate kinase, malate dehydrogenase, GDP-mannose 3, 5-epimerasel, ascorbate peroxidase and glutathione-S-transferase could consistently enhance their activity.  

This study exhibited the dynamic changes of protein phosphorylation status in rice embryo during germination and provided new insight in understanding the mechanism underlying this process. 

This work was supported by the National Natural Science Foundation of China, 100 talents program of Chinese Academy of Sciences, and Sino-Africa Joint Research Project. Results were published in Plant & cell physiology entitled “Gel-based comparative phosphoproteomic analysis on rice embryo during Germination”.