Ocotea catharinensis is a forest tree species from Mata Atlântica that has economic importance due to its wood and essential oils.  O. catharinensis became an endangered species mostly because of its intense exploitation and its low seed production and viability. The objective of this work was to study O. catharinensis somatic embryogenesis through the comparative proteome analysis of different embryogenic stages as well as cell aggregates maintained in different culture media that produce distinct cell embryogenic competence. For that, the protein extracts of cell aggregates (calus) cultured in different medias (WPM, MS, MS+2,4‑D) and somatic embryos in globular (E1), initial cotiledonary (E2), intermediary cotiledonary (E3) and mature embryo (E4) stages were subjected to two-dimensional gel electrophoresis (2-DE). The samples were ground with liquid N₂ and glass powder, precipitated with TCA/acetone solution followed by extraction and solubilization in 2‑DE buffer. The protein concentration was determined using Plus One 2D QuantKit (GE Healthcare). The samples were submitted to isoelectric focusing using pH 4-7 immobilized pH gradient (IPG) strips. We also carried out “two‑in‑one” gels (Wang et al., 2003) of cell aggregates, where IPG strips with the same pH range for two different samples were loaded side‑by‑side on top of a vertical SDS‑PAGE gel for separation in the second dimension. After silver staining, the gel images were digitalized and subjected to computational analyses in order to quantify the number and intensity of the spots, allowing the determination of protein differential expression. Few protein spots showed different intensities during the development and in the different culture media tested. These spots are presently being analysed by mass spectrometry using MALDI‑TOF and ESI‑Q‑TOF‑MS/MS.

(Supported by CAPES)