Abstract
Salvia miltiorrhiza is a renowned model medicinal plant species for which 15 SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) family genes have been identified; however, the specific functions of SmSPLs have not been well characterized as of yet. For this study, the expression patterns of SmSPL6 were determined through its responses to treatments of exogenous hormones, including indole acetic acid (IAA), gibberellic acid (GA3), methyl jasmonic acid (MeJA), and abscisic acid (ABA). To characterize its functionality, we obtained SmSPL6-ovexpressed transgenic S. miltiorrhiza plants and found that overexpressed SmSPL6 promoted the accumulation of phenolic acids and repressed the biosynthesis of anthocyanin. Meanwhile, the root lengths of the SmSPL6-overexpressed lines were significantly longer than the control; however, both the fresh weights and lateral root numbers decreased. Further investigations indicated that SmSPL6 regulated the biosynthesis of phenolic acid by directly binding to the promoter regions of the enzyme genes Sm4CL9 and SmCYP98A14 and activated their expression. We concluded that SmSPL6 regulates not only the biosynthesis of phenolic acids, but also the development of roots in S. miltiorrhiza.
Highlights
Salvia miltiorrhiza Bunge, which belongs to the Labiatae family, is a significant medicinal plant [1]
The results of quantitative reverse transcription PCR (qRT-PCR) revealed that S. miltiorrhiza SPL6 (SmSPL6) responded to indole acetic acid (IAA), GA3, methyl jasmonic acid (MeJA), and abscisic acid (ABA) treatments
Elicitors can affect phenolic acid compounds via transcription factors, which activate or repress the expression of enzyme genes that are engaged in the phenolic acid biosynthetic pathway
Summary
Salvia miltiorrhiza Bunge, which belongs to the Labiatae family, is a significant medicinal plant [1]. Lipid-soluble tanshinones and water-soluble phenolic acids are the main active ingredients of S. miltiorrhiza [1,8]. The biological activities of lipid-soluble tanshinones, such as tanshinone and tanshinol A, include cardio-cerebrovascular protection and serve as anticancer and anti-inflammatory agents [9]. Hydrophilic phenolic acids, such as salvianolic acid B (SalB) and rosmarinic acid (RA), have potent anti-oxidative, anti-coagulation, and anti-inflammatory properties [10]. As the main active ingredient of phenolic acids, SalB is designated as a primary component of Danshen in the official Chinese Pharmacopoeia [11]. In S. miltiorrhiza, the biosynthesis of RA and SalB originates from phenylpropanoid and tyrosine-derived pathways [12]. The expression of SmMYB111 can positively regulate the accumulation of phenolic acids [17]
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