Analysis of CHS gene polymorphisms and function in X-ray irradiated Glycyrrhiza uralensis

Chalcone synthase (CHS) is the rate-limiting enzyme involved in the biosynthetic pathway of flavonoids in Glycyrrhiza uralensis. It plays an important role in the regulation and control of flavonoids biosynthesis. In this study, X-ray irradiated G. uralensis samples with high or low content of flavonoids were studied. The CHS gene polymorphism in these samples were analyzed, the specific haplotypes were identified, and CHS function was parsed. 109 CHS cDNA sequences with a length of 1 170 bp were cloned, 220 variable sites (116 missense mutation sites) were found and 85 haplotypes were identified, which encoded 65 amino acid sequences with 96 variable sites. aa-20 and aa-45 were the most common amino acid sequences in samples with high flavonoid content, while aa-11 was the most sequence in samples with low flavonoid content. Molecular docking results showed that the mutation sites at 383 in aa-20 and 229 in aa-45 were related to substrate binding, while the mutation sites at 383 and 229 in aa-11 were not involved. Therefore, we speculate that the two mutation sites have significant influence on the function of CHS. We analyzed a large number of CHS cDNA sequences and identified the important functional sites, which will provide a basis for further functional studies. This paper will provide ideas for further research of the molecular regulation of the flavonoid biosynthetic pathway in G. uralensis.