CLONING AND EXPRESSION ANALYSIS OF SOMATIC EMBRYOGENESIS RELATED SERK GENE IN FRAXINUS MANDSHURICA

In order to investigate the molecular mechanism of somatic embryogenesis in Fraxinus mandshurica, genome DNA and RNA from Fraxinus mandshurica's somatic embryos and callus tissue were used as templates. Using NCBI database to obtain the CDS sequence of SERK homologous gene of similar species and the full-length of cDNA of SERK gene was obtained by PCR amplification and RACE technique. Sequencing results show that the encoding sequence's full length is 1884bp, code 672 amino acid, named it FmSERK (GenBank No. KT071544). Protein structure and cluster analysis showed that the FmSERK gene has the common structural domain characteristic with SERK gene family of other species: one SP signal peptide, one leucine zipper structure domain, five leucine repetitive sequence structural domain LRR, one SPP serine - proline - proline motif, one TM transmembrane domain, three domains of intracellular kinase activity and C terminal domain features. The expression of SERK gene in different organs, tissues, body embryo development stage and embryo culture stage were analysed and showed that the SERK gene was expressed at various stages of different organs and tissues of Fraxinus mandshurica. However, the expression quantity was very different, the expression quantity was the lowest in spherical embryo period, the expression quantity of cotyledon was the highest, and the expression of mature embryo was decreased. The expression of SERK gene was the highest when 35 d was induced, it indicated that SERK gene plays an important regulatory role in the development of somatic embryos and is the marker gene of somatic embryos.