Proteomics of embryogenic and non-embryogenic calli of a Liriodendron hybrid

An increasing interest is focused on somatic embryogenesis induction in plants. This process usually generates both embryogenic calli (EC) and non-embryogenic calli (NEC) from the same explant. To identify specific proteins involved in embryogenesis competence, a comparative proteomics of EC and NEC in Liriodendron hybrid was performed. Proteins of EC and NEC were separated by two-dimensional gel electrophoresis (2-DE) and 14 proteins specific embryogenesis were characterized by matrix-assisted laser desorption ionization time-of-flight/- time-of-flight. Among these identifying proteins, profilin may be indispensable for cell survival and division, and eIF- 5A may play a functional role in embryogenic competence and further embryo development. Regulation of programmed cell death by cathepsin b-like cysteine proteinase and proteasome 20S beta1.1 subunit may have an essential part in maintaining cellular pluripotency and reprogramming for embryogenic mass. Reactive oxygen species (ROS) have a central effect on triggering cell division. However, methionine sulfoxide reductase is probably involved in protecting the cell from damage from excessive reactive oxygen species. Expression of EF-hand family proteins in embryogenic calli may mediate the calcium ion gradient for polarization and organ patterning. These identified embryogenic calli-specific proteins provide clues to understanding low conversion rate from calli cells to embryogenic cells.