CORRELATION BETWEEN DNA METHYLATION OF THE CHALCONE ISOMERASE GENE IN LITHOCARPUS POLYSTACHYUS REHD. (FAGACEAE) AND PHLORIZIN ACCUMULATION

Chalcone isomerase gene (CHI) is an important gene that flavonoid biosynthesis pathway. This study aimed at investigating the effects of DNA methylation in the CHI promoter of Lithocarpus polystachyus Rehd, gene expression levels and phlorizin accumulation. Primers were designed based on the cDNA sequence of the chalcone isomerase gene (CHI) from Lithocarpus polystachyus Rehd and the promoter sequence was cloned using TAIL-PCR technology. The CpG Island of the gene promoter was predicted using online software, and the DNA methylation sites of the CHI promoter was investigated through bisulfite sequencing. QRT-PCR was used to detect the expression levels of CHI at varying DNA methylation levels and types. Ultra-pressure liquid chromatography (UPLC) was used to determine the phlorizin quantity. The full-length promoter sequence of CHI was 2141 bp, with 33 types, 138 cis-acting elements (CREs), 3 CpG islands, 16 methylation sites, and 7 DNA methylation types. DNA methylation of the CHI gene promoter region was significantly negatively correlated with gene expression and phlorizin content (p<0.01. The successfully cloning of the CHI gene promoter and its DNA methylation lays the foundation for further research on gene expression analysis and flavonoid biosynthesis in L. polystachyus.