Abstract:

In this study，methylation sensitive amplification polymorphism（MSAP）analysis was performed in dwarf ornamental Cunninghamia lanceolata（dwarf-type）and wild-type，to characterize the DNA methylation levels and patterns of CCGG sites in leaves and xylem. A total of 745 CCGG loci were both amplified in leaf of dwarf-type and wild-type using 20 primer combinations. And among them，508（68.17%）and 505（67.83%）loci were methylated respectively. While the primer combinations totally amplified 742 and 737 CCGG loci，respectively in the xylem of dwarf-type and wild-type. A 63.52% of loci were methylated in the xylem of dwarf-type，which was significantly less than that of wild-type（67.51%）. It was found that the DNA methylation patterns changed in dwarf-type compared with wild-type. The hypermethylation rate was higher than hypermethylation rate both in leaves and xylem.Subsequent cloning and analysis of methylation DNA sequences showed that methylation level of IBR5 promoter sequence increased in dwarf-type. IBR5 is a phosphatase that modulates phytohormone signal transduction. Therefore，it was inferable that methylation of genes involved in phytohormone signal transduction could be a cause of dwarf-type formation.

Key words: Cunninghamia lanceolata, Chinese fir, dwarf variation, DNA methylation, methylation-sensitive amplification polymorphism（MSAP）