Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest of China, Shaanxi Normal University, Xi'an 710062, China.
College of Life Science, Luoyang Normal University, Luoyang 471934, China.
Plant Sci. 2021 Sep;310:110993. doi: 10.1016/j.plantsci.2021.110993. Epub 2021 Jul 17.
Plant-specific SQUAMOSA promoter-binding protein-like (SPL) transcription factors play critical regulatory roles during plant growth and development. However, the functions of SPLs in Salvia miltiorrhiza (SmSPLs; a model medicinal plant) have not been reported. Here, the expression patterns and functions of SmSPL7 were characterized in S. miltiorrhiza. SmSPL7 was expressed in all parts of S. miltiorrhiza, with the highest expression level in the leaves, and could be inhibited by multiple hormones, including methyl jasmonate, auxin, abscisic acid, and gibberellin. SmSPL7 is localized within the nucleus and exhibits robust transcriptional activation activity. Transgenic lines overexpressing SmSPL7 demonstrated pronounced growth inhibition, accompanied by increased anthocyanin accumulation via the genetic activation of the anthocyanin biosynthesis pathway. However, SmSPL7 overexpression significantly decreased salvianolic acid B (SalB) production by inhibiting the transcripts of genes implicated in its biosynthesis pathway. Further analysis indicated that SmSPL7 directly binds to SmTAT1 and Sm4CL9 promoters and blocks their expression to inhibit the biosynthesis of SalB. Taken together, these results indicate that SmSPL7 is a negative regulator of SalB biosynthesis but positively regulates anthocyanin accumulation in S. miltiorrhiza. These findings provide new insights into the functionality of the SPL family while establishing an important foundation for further uncovering the crucial roles of SmSPL7 in the growth of S. miltiorrhiza.
植物特有的 SQUAMOSA 启动子结合蛋白样（SPL）转录因子在植物生长和发育过程中发挥着关键的调节作用。然而，SPL 在丹参（SmSPLs；一种模式药用植物）中的功能尚未报道。在这里，我们对丹参 SmSPL7 的表达模式和功能进行了研究。SmSPL7 在丹参的所有部位都有表达，在叶片中的表达水平最高，并且可以被多种激素抑制，包括茉莉酸甲酯、生长素、脱落酸和赤霉素。SmSPL7 定位于细胞核内，具有强大的转录激活活性。过表达 SmSPL7 的转基因株系表现出明显的生长抑制，同时通过激活花青素生物合成途径，导致花青素积累增加。然而，SmSPL7 的过表达通过抑制其生物合成途径相关基因的转录，显著降低了丹参酸 B（SalB）的产量。进一步的分析表明，SmSPL7 直接结合 SmTAT1 和 Sm4CL9 启动子，并阻断它们的表达，从而抑制 SalB 的生物合成。综上所述，这些结果表明 SmSPL7 是 SalB 生物合成的负调控因子，但正向调控丹参中花青素的积累。这些发现为 SPL 家族的功能提供了新的见解，并为进一步揭示 SmSPL7 在丹参生长中的关键作用奠定了重要基础。
