Molecular cloning and transcriptional analysis of WRKY and solavetivone biosynthetic genes in the hairy roots of Hyoscyamus albus

• The premnaspirodiene synthase hatps1 was cloned from Hyoscyamus albus hairy roots.
• The premnaspirodiene oxygenase hahpo1 was cloned from Hyoscyamus albus hairy roots.
• The hatps1 and hahpo1 promoters contain W-boxes, which are WRKY cis-elements.
• The class IIa WRKY hawrky1 was cloned from Hyoscyamus albus hairy roots.
• The induction pattern of hawrky1 matched that of hahpo1.

The hairy roots of Hyoscyamus albus (HAHR) produce a variety of sesquiterpene-type phytoalexins after different chemical treatments. In a previous study, solavetivone and its derivatives were produced after methyl jasmonate (MeJA) treatments, with or without copper sulfate (CuSO4), but not after treatments of only CuSO4. In this study, two putative solavetivone biosynthetic gene, H. albus terpene synthase 1 (hatps1) and H. albus Hyoscyamus premnaspirodiene oxygenase 1 (hahpo1), were cloned. The WRKY transcription factor DNA-binding element, the W-box, was identified in the hatps1 and hahpo1 promoters. The WRKY transcription factor, H. albus wrky transcription factor 1 (hawrky1), was cloned under solavetivone production conditions. From the phylogenetic analysis, hawrky1 was classified as group IIa. A transcriptional analysis showed that hawrky1 was induced by a MeJA treatment, with or without CuSO4, but not by a treatment of only CuSO4. The expression pattern of hawrky1 matched that of the hahpo1. These results indicate that hawrky1 may be an important gene that activates the production of solavetivone in H. albus.