Comparison of Protein Profiles during Cotton (Gossypium hirsutum L.) Fiber Cell Development with Partial Sequences of Two Proteins

Two-dimensional polyacrylamide gel electrophoresis was used to compare the protein profiles of cotton ( Gossypium hirsutum L.) fiber cells at two developmental stages. In the first stage, the cells are elongating and synthesizing primary cell walls [14 days postanthesis (DPA)]; in the second stage, the cells are beginning secondary cell wall synthesis [21 DPA]. Forty-five proteins were found that differed in amount between the two stages; these proteins were characterized by their molecular weights, isoelectric points, and relative quantities at each stage. Two of the proteins that were present in higher amounts in the 21-DPA fiber were further studied by N-terminal amino acid sequencing. One of these proteins was identified as a cytoplasmic malate dehydrogenase on the basis of N-terminal sequence similarity. These results provide a foundation for further studies of the proteins that participate in cotton fiber development. Keywords: Gossypium hirsutum L.; Malvaceae; cotton; fiber; two-dimensional electrophoresis; proteins; malate dehydrogenase