No abstract

Abstract:The potential of immature zygotic embryos to produce embryogenic tissue was tested using culture media differed in inorganic salt composition as well as plant growth regulator content. Explants cultured on DCR as well as MLV media gave the highest initiation percentages with maximum values of 8.8% (MLV) to 10.4% (DCR). Plant growth regulators content (standard or reduced) had no profound effect on embryogenic tissue initiation. Somatic embryo maturation as well as germination was dependent on the cell line and salt composition of the medium. Plantlet regeneration occurred in three cell lines out of five tested. During the maturation process profound changes occurred in the internal organisation of somatic embryos such differentiation of root meristem in precotyledonary somatic embryos and formation of provascular strands in cotyledonary somatic embryos.

Glucanase and chitinase enzymes play an important role in different plant processes including defense against pathogens and morphogenesis. Moreover, their role in the processes of somatic embryogenesis has been demonstrated. It has been suggested, that the presence of this type of proteins might be a marker for embryogenic potential of callus cultures. In this work we screened for the presence of glucanases and chitinases in liquid growth media of a set of conifer embryogenic cell lines in order to find correlation with their embryogenic potential. We have found that none of the 12 chitinase isoforms detected in culture media of Pinus nigra Arn. or the nine chitinases detected in media with Abies alba × A. cephalonica and Abies alba × A. numidica embryogenic tissues could be linked to their embryogenic capacity. Similarly, none of the six glucanase isoforms detected in the extracellular fluid of Pinus nigra Arn. cultures can be assigned as a marker of embryogenic potential. Thus, our data indicate the large variability and doubtless importance of glucanases and chitinases for cell growth and development of somatic embryos, however, do not support the premise that they are markers of embryogenesis.