Analysis of Proteins Associated with Storage Root Formation in Cassava Using Two-dimensional Gel Electrophoresis

ABASTRACT Two-dimensional gel electrophoresis analysis was performed on adventitious and storage root in cassava (Manihot esculenta Crantz). Adventitious root lacking swelling formation and swelled storage root were obtained from the accession WU104 grown in the green house of the Department of Biology in Washington University in St. Louis (MO-USA). Saline buffer-soluble proteins were extracted, separated in a high-resolution 2-D electrophoresis system, visualized with silver staining gel procedure, and digital image generate for further analysis. Quantitative and qualitative protein spots analysis was performed with a computer assisted image software system. Results revealed large variation in the complexity of the gel protein profile between the two root systems. About 90% of the protein spots appeared in the pI range value of 4.0 to 6.5 and between 14 to 80 Kda of molecular mass. Detailed computer assisted analysis of this gel allowed us to establish 5 distinct classes of protein based on spot quantification that could be associated with swelling and non-swelling roots. Variation in the complexity of protein pattern was related with different type of root. Whereas the adventitious root showed a more simple profile related to primary growth, the storage root showed to be a more complex profile related to secondary growth and starch accumulation.