Study On The Relationship Between Nitric Oxide-treated Production Of Plant Secondary Metabolite Isoflavone And DNA Methylation

Nitric oxide is an important molecule that is wide spread in plants. It regulates plants growth and development, and also mediates signal pathway that is involved in many defense responses of plants. It is known that NO could stimulate biosynthesis of secondary metabolites in plants, but the function mechanism is not very clear yet.To determine the role of NO in secondary metabolite production of plant cells, sodium nitroprusside (SNP) was utilized as the NO donor to investigate its effect on the production of isoflavone and changes in DNA methylation in Maackia amurensis cell suspension cultures. The results were as following.Firstly, NO significantly stimulated the production of isoflavone in M. amurensis cells. When treated with 50μmol/L SNP, the isoflavone content was 2.82-fold higher than the untreated. SNP-induced isoflavone production was blocked by NO specific scavenger 2-phenyl-4,4,5,5-tetramethyllimidazoline-l-oxyl-3-oxide. Secondly, NO also activated the activity of phenylalanine-ammonia lyase (PAL), and aminooxy acetic acid (AOAA), a common PAL inhibitor, strongly attenuated SNP-induced isoflavone production. It indicated that the SNP-induced isoflavone production was de novo. Thirdly, NO treatment caused DNA methylation level in M. amurensis cells higer than untreated, and the trend of DNA methylation changes was closely related to the isoflavone production. Pretreatment with DNA methyltransferase inhibitor 5-azacytidine suppressed SNP-induced isoflavone production.In conclusion, the results suggested that NO released from SNP triggered isoflavone biosynthesis in M. amurensis cells was related to DNA methylation.