Lignin is a critical component of the closing layer of the potato (Solanum tuberosum L.) tuber during healing; however, the molecular mechanism of its formation remains poorly understood. To elucidate the molecular mechanism of tuber healing, we screened the genes encoding transcription factors that regulate lignin synthesis(StMYB24/49/105/144/168, StWRKY19/20/22/23/34) and the key genes involved in lignin monomer synthesis (PHENYLALANINE AMMONIA LYASE 5 (StPAL5) and CINNAMYL ALCOHOL DEHYDROGENASE 14 (StCAD14)) for induced expression after wounding using transcriptome data. DLR, Y1H, EMSA, and ChIP-qPCR assays revealed that StMYB168 could bind directly to the StPAL5 and StCAD14 promoters to activate their expression and that StWRKY20 enhanced this regulation with a synergistic effect. Y2H, BiFC, and Co-IP assays showed that StMYB168 interacted with StWRKY20 to form a MYB-WRKY complex. Furthermore, transient overexpression of StMYB168 and StWRKY20 in Nicotiana benthamiana leaves upregulated the expression of NbPAL and NbCAD10 and promoted lignin accumulation in the leaves. In addition, overexpression of StWRKY20 and StMYB168 together resulted in higher expression levels of NbPAL and NbCAD10 and higher levels of lignin monomer and total lignin. In contrast, silencing of StMYB168 and StWRKY20 in potato significantly reduced the lignin content of wounded tubers. In conclusion, StMYB168 and StWRKY20 are important regulators of lignin biosynthesis in potato tubers during healing and can positively regulate lignin biosynthesis by forming a complex. The elucidation of this regulatory module provides information on the regulatory mechanism of lignin monomer synthesis in wounded tubers at the transcriptional level.

中文翻译：

---

MYB168 和 WRKY20 转录因子在马铃薯块茎伤口愈合过程中协同调节木质素单体合成


木质素是马铃薯 （Solanum tuberosum L.） 块茎愈合过程中闭合层的关键成分;然而，其形成的分子机制仍然知之甚少。为了阐明块茎愈合的分子机制，我们筛选了编码调节木质素合成的转录因子的基因 （StMYB24/49/105/144/168， StWRKY19/20/22/23/34） 和参与木质素单体合成的关键基因 （苯丙氨酸解氨酶 5 （StPAL5） 和肉桂醇脱氢酶 14 （StCAD14））使用转录组数据诱导损伤后表达。DLR、Y1H、EMSA 和 ChIP-qPCR 检测显示，StMYB168 可以直接与 StPAL5 和 StCAD14 启动子结合以激活它们的表达，并且 StWRKY20 通过协同作用增强这种调节。Y2H、BiFC 和 Co-IP 检测结果显示，StMYB168 与 StWRKY20 相互作用形成 MYB-WRKY 复合物。此外，StMYB168 和 StWRKY20 在本氏烟草叶片中的瞬时过表达上调了 NbPAL 和 NbCAD10 的表达，促进了叶片中木质素的积累。此外，StWRKY20 和 StMYB168 的过表达导致 NbPAL 和 NbCAD10 的表达水平升高，木质素单体和总木质素的表达水平升高。相比之下，马铃薯中 StMYB168 和 StWRKY20 的沉默显著降低了受伤块茎的木质素含量。综上所述，StMYB168 和 StWRKY20 是马铃薯块茎愈合过程中木质素生物合成的重要调节因子，可通过形成复合物正向调节木质素生物合成。该调节模块的阐明提供了有关转录水平受伤块茎中木质素单体合成的调节机制的信息。