Cloning and expression analysis of a new chalcone isomerase gene during flowering in safflower

Abstract

Flowers of safflower (Carthamus tinctorius L.) have been widely used in traditional Chinese medicine because of their abilityto improve cerebral blood flow. The major active ingredients in safflower are flavonoids. To date, few flavonoid biosynthesis genes havebeen cloned from this species. In our previous research, four isoform chalcone isomerase genes were screened. In this study, a newchalcone isomerase gene (designated as CtCHI-N) was cloned from a safflower cDNA library. A 696-bp cDNA for CtCHI-N was cloned,and its sequence was subsequently analyzed. The recombinant protein was successfully expressed in a prokaryotic expression system,and the expression of CtCHI-N in different tissues and at different stages of flowering was investigated. The results showed that CtCHI-Nwas expressed in a tissue-specific manner, and the greatest expression level occurred during early flowering. In addition, flavonoids atdifferent stages of flowering were also measured, and the expression of CtCHI-N was found to correlate with flavonoid biosynthesisduring flowering. CtCHI-N was successfully cloned in the experiment, and expression analysis revealed that CtCHI-N might influenceflavonoid biosynthesis during flowering in safflower.