Proteomic analysis of tung tree (Vernicia fordii) oilseeds during the developmental stages

Authors: ZHAN, ZHIYONG - Chinese Academy Of Forestry; CHEN, YICUN - Chinese Academy Of Forestry; Shockey, Jay; HAN, XIAOJIAO - Chinese Academy Of Forestry; WANG, YANGDONG - Chinese Academy Of Forestry

Submitted to: Molecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2016
Publication Date: 11/8/2016
Citation: Zhan, Z., Chen, Y., Shockey, J., Han, X., Wang, Y. 2016. Proteomic analysis of tung tree (Vernicia fordii) oilseeds during the developmental stages. Molecules. 21:1486.

Interpretive Summary: While it has been well-understood that most vegetable oils are stored in the form of lipid droplets in the seeds of oil-accumulating plants, the processes that control the timing of oil deposition are not well known. In particular, only a few enzymes and structural proteins that make up the protein component of lipid droplets in seeds have been identified, despite the presence of dozens or hundreds of other proteins being present in this organelle. In the present study, we have sought to identify proteins present in the oilbody fraction of developing tung tree seeds. At least 144 proteins that vary in concentration during different stages of seed development were identified using cutting edge technologies. Most of these proteins were identified as participating in three main categories of metabolism, including fatty acid metabolism. This class of proteins in particular will be useful in future efforts to engineer agronomic oilseed crops to produce novel industrial oils like tung oil.

Technical Abstract: Tung tree (Vernicia fordii), a non-model woody plant belonging to the Euphorbiaceae family, is a promising economic plant due to the high content of novel high-value oil in its seeds. Many metabolic pathways are active during seed development. Oil (triacylglycerols or TAGs) accumulates in oil bodies distributed in endosperm cells of tung tree seeds. The relationship between oil bodies and oil content during tung tree seed development was analyzed by ultrastructural observation, which confirmed that oil accumulation was correlated with the volumes and numbers of oil bodies in endosperm cells during three different developmental stages. For a deeper understanding of seed development, we carried out proteomics analyses. At least 144 proteins were differentially expressed during three different developmental stages. 76 proteins were successfully identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry/mass spectrometry (MALDI-TOF/MS/MS). These proteins were grouped into 11 classes according to their functions. The major groups of differentially-expressed proteins are associated with energy metabolism (25%), fatty acid metabolism (15.79%) and defense-related (14.47%). These results strongly suggested that a very high percentage of gene expression in seed development is dedicated to the synthesis and accumulation of TAG.