Methylation of Exogenous Promoters Regulates Soybean Isoflavone Synthase (GmIFS) Transgene in T0 Transgenic Wheat (Triticum aestivum)

Abstract

DNA methylation is one epigenetic strategy for gene regulation in living organisms. In this study, the expression of soybean isoflavone synthase (GmIFS) transgene in T0 transgenic wheat plants was investigated at the RNA and the final product genestin level. T0 plants showed variations in the GmIFS expression. Methylation status of the exogenous promoters (35S or Oleocin (OL)) proximal sequence was investigated in T0 plants using bisulphite sequencing to disclose their methylation in parallel with the GmIFS level of expression. Results concluded that the high GmIFS expressers of T0 plants exhibited high methylation of exogenous promoter proximal sequences as well as low expression of DNA methyltransferases (Mets). Variation in GmIFS was associated with the level of methylation in the 35S or OL promoters. High expression of GmIFS was negatively correlated with methylation level of 35S and OL promoter proximal regions. In 35S promoter, methylation level of the CpG sites –56 and –88 is strongly linked to GmIFS expression and is involved in the regulation of GmIFS gene. In OL promoter, the CpG site could be involved in the regulation of the GmIFS. Wheat Met3 expression varied among T0 transgenic plants. Its expression profile could explain the regulation of GmIFS transgene by methylation.