Evaluation of the Extracellular Proteome Profile During the Somatic Embryogenesis Process of Coffea spp.

Abstract

The somatic embryogenesis (SE) has been used as an important tool for the study of molecular events in plant cell differentiation. Some studies have revealed that suspensions of somatic embryos secrete a vast array of proteins that could be involved in the regulation of this process. Many of these molecules have been suggested to work as inductors and others as inhibitors of the process. In the present work, suspension cultures of both Coffea canephora and Coffea arabica were used to study the population of proteins secreted into the media. Two types of cultures were used; one for the propagation of suspension cultures (non-embryogenic) and another for the induction of SE (embryogenic). The evaluated days were 14 and 42 for non-embryogenic condition and 21, 42, and 98 for the embryogenic condition. An embryogenic system was established in the C. arabica species, obtaining 4,000 embryos per liter. We analyzed the proteins secreted into the culture media, both under non-embryogenic and SE induction conditions. In C. canephora medium, we found 173 proteins after 14 d of culture under non-embryogenic conditions. In C. arabica we found 523 after 14 d under non-embryogenic conditions. Under embryogenic conditions we found 379, 409 and 175 proteins after 21, 42 and 98 d, respectively. We also determined that some proteins are secreted exclusively under embryogenic conditions and others proteins under non-embryogenic conditions.