Involvement of peroxidase activity in developing somatic embryos of Medicago arborea L. Identification of an isozyme peroxidase as biochemical marker of somatic embryogenesis

The legume Medicago arborea L. is very interesting as regards the regeneration of marginal arid soils. The problem is that it does not have a good germinative yield. It was therefore decided to regenerate via somatic embryogenesis and find a marker of embryogenic potential. In this study, peroxidase activity was evaluated in non-embryogenic and embryogenic calli from M. arborea L. A decrease in soluble peroxidase activity is observed in its embryonic calli at the time at which the somatic embryos begin to appear. This activity is always lower in embryonic calli than in non-embryonic ones (unlike what happens in the case of wall-bound peroxidases). These results suggest that peroxidases can be considered to be enzymes involved in somatic embryogenesis in M. arborea. In addition, isozyme analyses were carried out on protein extracts using polyacrylamide gel electrophoresis. The band called P5 was detected only in embryogenic cultures at very early stages of development. This band was digested with trypsin and analyzed using linear ion trap (LTQ) mass spectrometer. In P5 isoform a peroxidase-l-ascorbate peroxidase was identified. It can be used as a marker that allows the identification of embryological potential.