目的 对虎杖中1个新的R2R3-MYB转录因子基因PcMYB1进行转录活性鉴定和表达特性分析，并在转基因拟南芥中进行功能研究。方法 利用酵母单杂交实验分析PcMYB1的转录活性；荧光定量PCR（RT-PCR）技术检测虎杖中PcMYB1的表达模式；利用Wiesner染色和溴乙酰法检测PcMYB1转基因拟南芥中的木质素含量；RT-PCR技术分析PcMYB1转基因拟南芥木质素合成相关基因的表达。结果 酵母单杂实验结果表明，PcMYB1具有转录抑制活性；RT-PCR结果显示PcMYB1在虎杖根、茎、叶中均有表达，在叶中表达量最高，并且紫外照射处理可诱导叶片中PcMYB1的表达；与野生型拟南芥相比，转基因拟南芥的株高降低了24.07%，木质部的细胞染色程度浅，转基因拟南芥木质素含量降低了14.81%，参与木质素合成的AtC4H、AtC3H、AtF5H、AtCOMT、AtCAD基因表达下调。结论 PcMYB1具有转录抑制活性，对植物木质素合成具有负调控作用。

Objective To identify the transcriptional activity and expression profile of PcMYB1, encoding a new R2R3-MYB transcription factor from Polygonum cuspidatum, and evaluate the biological functions of PcMYB1 in transgenic Arabidopsis thaliana. Methods The yeast one-hybrid system assay was conducted to test the transcriptional activity of PcMYB1. The tissue-specific expression profiles of PcMYB1 and the gene expression of P. cuspidatum leaves in response to UV-C irradiation were analyzed by RT-PCR analysis. To assess the biological functions of PcMYB1, the gene was expressed in A. thaliana under the control of CaMV 35S promoter. To obtain information about the lignin composition, cross-sections of the basal part of the inflorescence stem of wild-type and transgenic A. thaliana plants were treated with Wiesner staining, and the lignin content was measured by acetyl bromide method. RT-PCR analysis was used to determine expression levels of the genes encoding the enzymes of lignin biosynthesis. Results After expression of reporter and effector constructed in yeast, β-galactosidase assays showed that the transcriptional activation activity of VP16 domain was reduced markedly when fused to PcMYB1 protein, indicating that PcMYB1 has transcriptional repression activities. Expression pattern analysis showed that PcMYB1 was widely expressed in all tissues examined, but predominantly in leaves. PcMYB1 showed a peak of transcription at 6 h post UV-C treatment. The transgenic lines with reduction in height was 24.07% shorter than the wild-type plants. Wiesner staining of lignin in stem cross-sections revealed the typical intense red stain of secondary cell walls in wild-type plants, but less intense staining was detected in transgenic plants, and lignin accumulation was significantly decreased (about 14.81%) in transgenic plants stems. The expression of genes involved in the lignin biosynthetic pathway, including AtC4H, AtC3H, AtF5H, AtCOMT, and AtCAD, were down-regulated in transgenic lines compared to wild-type plants. Conclusion Taken together, this study provided the evidence for the biological functions of PcMYB1 as a negative regulator of lignin pathway.

R282.12

国家自然科学基金项目（81803670）；长江大学校级大学生创新训练计划项目（2019279）