Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2007
Publication Date: 10/26/2007
Citation: Ahn, Y., Chen, G.Q. 2007. Temporal and spatial expression of 2s albumin in castor (ricinus communis l.). Journal of Agricultural and Food Chemistry. 55:10043-10049.
Interpretive Summary: Castor oil is the only commercial source of hydroxy fatty acid that has numerous industrial applications. Due to the presence of ricin toxin and hyper-allergenic 2S albumins in the seed, it is desirable to remove the ricin and 2S albumins from castor seeds. We are investigating the expression profiles of the 2S albumin to understand its expression pattern. The results provide information to the development of a safe castor crop through genetic engineering.
Technical Abstract: We studied the temporal and spatial expression of the 2S albumin in castor (Ricinus communis L.) during seed development, germination, post-germination, and plant development. Quantitative PCR analysis showed that the 2S albumin transcript accumulated to a maximum level at the middle of seed development, showing a bell-shaped temporal pattern. Residual levels of the transcript were present in the mature seed and degraded rapidly upon germination. Immunodetection analysis was performed using an anti-2S albumin antibody under reducing conditions. During seed development, the 2S albumin precursor pro-protein began to be synthesized when the 2S albumin transcript level increased; it was timely processed to mature 2S albumins. Both the 2S albumin precursor pro-protein and mature proteins accumulated throughout seed maturation and desiccation stages. During seed germination, both forms of the 2S albumin proteins were present in endosperm and cotyledon until the completion of germination and degraded rapidly afterwards. However, the antibody also detected a group of newly synthesized proteins in endosperm and cotyledon when the seeds progressed to germination and post-germination stages. A 14 kDa protein in the leaves of fully developed seedlings and mature plants also reacted to the anti-2S albumin antibody. Since the temporal and spatial expression patterns of these proteins do not associate with the known function of castor 2S albumin as a storage protein, they may play other biological roles in germinating seeds or leaves.