Sequential expression of key genes in proline, glycine betaine and artemisinin biosynthesis of Artemisia aucheri Boiss using salicylic acid under in vitro osmotic stress

Artemisia aucheri belongs to the Asteraceae family, which is known for its medicinal and aromatic properties. The present study was conducted to elucidate the influence of salicylic acid (SA) pretreatment on proline and glycine betaine (GB) metabolism as well as artemisinin biosynthesis in A. aucheri under in vitro osmotic stress (˗0.6 MPa) induced by polyethylene glycol (PEG). The expression of ∆1-pyrroline-5-carboxylate synthetase (P5CS) and betaine aldehyde dehydrogenase (BADH) genes and related enzymes were enhanced under osmotic stress. SA pretreatment improved accumulation of proline and GB and increased the expression of BADH and P5CS enzyme activity under osmotic stress. However, proline dehydrogenase (PDH) gene expression and PDH activity were not affected by osmotic stress and SA pretreatments. In addition, SA in combination with or without PEG induced expression of the key genes involved in artemisinin biosynthesis and increased artemisinin content. These findings indicated that, higher accumulation of proline and GB under osmotic stress by SA is possibly due to increasing of osmoprotectants biosynthesis. This study suggested that A. aucheri is one of the potential species for artemisinin biosynthesis under environmental stress and exogenous SA.