Unlike zygotic embryogenesis, during somatic embryogenesis an induction phase is required where
differentiated somatic cells acquire embryogenic potential. The transition of somatic cells to embryogenic
phase is the first and crucial step in somatic embryogenesis. This process involves reprogramming of
gene expression patterns as well as changes in the morphology, physiology and metabolism. These changes
are dependent on the up and down regulation of certain genes which are essential for the transition.
Although the mechanism is still unclear, the search for such genes led to the discovery of SERK gene. The
objective of the present study is to determine the expression pattern of the HbSERK gene during the
transition of somatic cells to the embryogenic state. In RT-PCR assay, no SERK transcripts could be detected
in somatic callus before embryo induction. However, the SERK expression was restricted in embryogenic
cells. Regarding the HbSERK expression in other tissues, no signal was found either in leaves or in nonembryogenic callus, but was observed in emerging shoot. Thus the present study demonstrated that in
addition to the acquisition of embryogenic competence, SERK gene also plays a role in shoot organogenesis
in Hevea.