Establishment of clary sage ( Salvia sclarea L.) regeneration system and development of glyphosate-tolerant clary sage plants through Agrobacterium-mediated genetic transformation

Clary sage (Salvia sclarea L.) is well known as a highly aromatic herbaceous plant and is commonly used in aromatic products and medicine. The biggest problem in the cultivation of clary sage is weeds, which not only entails a great cost of labor for weeding, but also leads to a great fluctuation in the yield and quality of its products. Therefore, there is a need to breed herbicide-resistant clary sage using genetic engineering. However, the lack of suitable regeneration and genetic transformation systems for clary sage has limited the process of molecular breeding. In this study, we firstly reported the regeneration system of clary sage, where explants from hypocotyls of sage induced adventitious shoots at a rate of 22.22 % when cultured on MS medium supplemented with 2.5 mg<middle dot>L-1 6-BA, 0.15 mg<middle dot>L-1 IAA, and 0.25 mg<middle dot>L-1 VC. Rooting of adventitious shoots was achieved at a rate of 94.44 % on 1/2 MS medium containing 0.125 mg<middle dot>L-1 NAA, 0.5 mg<middle dot>L-1 IAA, and 0.1 mg<middle dot>L-1 IBA. Secondly, based on the regeneration system, an efficient and stable Agrobacterium-mediated genetic transformation system was established in this paper, and the rate of genetic transformation was determined to be in the range of 3 %-5 % by transforming the hypocotyls of clary sage with pCAMBIA1301 vector and pCAMBIA1301-GR79-GAT vector. Finally, glyphosate tolerance was obtained from GR79 and GAT co-expressed clary sage plants in this study. This study not only lays the foundation of genetic transformation for the functional gene research and in-depth investigation of various biological problems of clary sage, but also provides a feasible genetic engineering solution for its industry to solve the weed problem, as well as a promotional role for precise molecular breeding of clary sage.