Improving the accumulation of 18 α -and 18 β -glycyrrhizins by over-expressing GuHMGR , GuSQS 1, and GuBAS genes in Glycyrrhiza uralensis

Abstract Objective To study the influence of over-expression of three functional genes involved in GC biosynthetic pathway, GuHMGR , GuSQS 1, and GuBAS on GC production. Methods Three plant expression vectors were constructed and transformed into Agrobacterium tumefaciens EHA105, which were used to infect Glycyrrhiza uralensis hypocotyls explants. After induction, selection, differentiation, culture, and transplantation, 12, 15, and 5 regenerated plants over-expressing GuHMGR , GuSQS 1, and GuBAS , were obtained, respectively. Results RT-PCR analysis showed these transgenic regenerated G. uralensis plants had 2–6 copies of GuHMGR , GuSQS 1, or GuBAS. HPLC analysis showed the contents of 18 α - and 18 β -GC in all transgenic regenerated samples were both higher than that in the blank control. With the increase of copy numbers of GuHMGR , GuSQS 1, and GuBAS , the contents of 18 α - and 18 β -GC were both increased in most samples. The highest 18 α - and 18 β -GC contents in transgenic regenerated plants were about 3.05 times and 2.80 times higher than that in the blank control, respectively. Conclusion Over-expression of the GuHMGR , GuSQS 1, and GuBAS genes enhance the accumulation of 18 α - and 18 β -GC in the roots and rhizomes of G. uralensis . We hope this work can lay a foundation for the molecular breeding research of G. uralensis and improving the quality of the roots and rhizomes of G. uralensis cultivars.