The importance of SmGRAS5 for metabolic engineering
The
biosynthesis of secondary metabolites usually involves multiple enzymes.
We can promote the accumulation of secondary metabolites by regulating
the expressions of these enzymes. Overexpression of artemisinin
biosynthesis gene FPS , CYP71AV1 , DXR significantly
increased the artemisinin content (Chen et al. , 2000; Shenet al. , 2012; Xiang et al. , 2012). Overexpressing the key
enzyme gene HMGR in the MVA pathway increased the content of
ajmalicine and catharanthine in Catharanthus roseus hairy roots
(Ayora-Talavera et al. , 2002). However, in most biosynthetic
pathways, the rate-limiting step is not limited to one or two enzymes.
TFs often target the key steps in biosynthetic pathways. Many TFs, such
as MYB, AP2/ERF, bHLH, and WRKY, have been reported to have global
regulatory functions in pharmaceutical
terpenoid
biosynthesis
(Xieet al. , 2012; Liu et al. , 2015; Lu et al. , 2016).
CrWRKY1, TcWRKY1 and AaWRKY1 can significantly improve the content of
serpentine, taxol and artemisinin biosynthesis in Catharanthus
roseus , Taxus chinensis and Artemisia annua , respectively
(Suttipanta et al ., 2011; Li et al ., 2012; Ma et
al. , 2009). Overexpression of AaORA in Artemisia annuasignificantly increased the expressions of several biosynthetic genes
including ADS , CYP71AV1 , and DBR2 , and led to a
significant increase in artemisinin production (Lu et al. , 2013).
SmGRAS5 as a positive regulator mediated GA-promoted diterpenoid
compound tanshinines biosynthesis by regulating the expression ofSmKSL1 and induce the anthocyanin, diterpenoid compound,
artemisinin, and triterpene saponins,
cannabidiolic
acid biosynthetic genes in transcriptome data (Solfanelli et
al. , 2006; Han et al. , 2013; Weiblen et al. , 2015; Guoet al. , 2016; Xiang et al. , 2012). Therefore, make full
use of TFs as a general tool to control metabolic pathways, is vital for
successful metabolic engineering.