Protein diversity of the extracellular matrix in somatic embryogenesis

Abstract

The somatic embryogenesis is the process by which somatic cells develop into plants through characteristic morphological stages . To induce the embryogenic potential, the medium needs to be supplemented with 2,4- dichlorophenoxiacetic acid (2,4-D) . Individual cell types in the heterogeneous cell populations produced different spectra of proteins, suggesting that the total profile of secreted proteins is a direct reflection of the cellular diversity in the cultures . The extracellular proteins role in somatic embryogenesis was indicated by three independent observations : (1) the defect in somatic embryogenesis process in several non- or low-embryogenic carrot lines was partially restored by the addition of secreted components from wild-type embryogenic cell lines ; (2) carrot somatic embryogenesis inhibited by tunicamicyn, an inhibitor of the N-glycosilation, was rescued by the addition of secreted glycoproteins present in embryo and cell suspension culture and (3) the tsll somatic embryo variant cell line, obtained by mutagenesis, was selected on the basis of the arrest in its embryo development at an elevated temperature by supplementing the medium with secreted proteins from wild type carrot cells . The characterization of extracellular proteins allows the search of molecular markers for embryogenic potential in cell cultures . Extracellular proteins identified as polysaccharides, proteglycanes, phosphatases, proteases, peroxidases, glycosiltransferases and chitinases has been reported in several cultures . The present paper intends to be a review of up to date research of secreted proteins present in the conditioned medium of different crops during the somatic embryogenesis process.