Cloning and characterization of two SERK genes to investigate the molecular basis of organogenesis and somatic embryogenesis in Cyclamen persicum

Somatic embryogenesis and organogenesis in vitro are essential for propagation, particularly for those species, such as Cyclamen spp., which can be only propagated in vitro. However, the genetic basis of the specification of the respective stem cells remains obscure. Since SOMATIC EMBRYOGENESIS RECEPTORLIKE KINASE (SERK) genes are involved in somatic embryogenesis as well as, in some species, in organogenesis, we searched for AtSERK homologs, in in vitro culture of Cyclamen persicum immature ovules. By a combination of 5'- and 3' Race approaches on RT-PCR templates, and of genome walking and IP-PCR strategies on genomic DNA templates, we eventually identified full cDNA and genomic sequences of two SERK-like genes named CpSERK1 (GenBank accession no. JF511659), and CpSERK2 (GenBank accession no. GU189408), as well as a partial cDNA fragment similar to AtSERK3 (GenBank accession no. EF661828). As in vitro culture of Cyclamen persicum immature ovules provide, in the same genotype and hormonal conditions, either lines forming organs and/or embryos or recalcitrant calli, this study aims to use CpSERK1 and CpSERK2 as tools to understand the molecular basis of stem cell formation and maintenance in somatic embryogenesis and organogenesis in vitro.