Co-Innovation Center for Sustainable Forestry in Southern China, Key Laboratory of Forest Genetics & Biotechnology, Ministry of Education, College of Biology and the Environment, Nanjing Forestry University. Nanjing, 210037, China.
Co-Innovation Center for Sustainable Forestry in Southern China, Key Laboratory of Forest Genetics & Biotechnology, Ministry of Education, College of Biology and the Environment, Nanjing Forestry University. Nanjing, 210037, China; Jiangsu Provincial Key Construction Laboratory of Special Biomass Resource Utilization, Nanjing Xiaozhuang University, Nanjing, 211171, China.
Plant Sci. 2020 Mar;292:110379. doi: 10.1016/j.plantsci.2019.110379. Epub 2019 Dec 17.
Plant defensins have been implicated in the plant defense system, but their role in poplar immunity is still unclear. In the present study, we present evidence that PtDefensin, a putative plant defensin, participates in the defense of poplar plants against Septotis populiperda infection. After the construction of recombinant plasmid PET-32a-PtDefensin, PtDefensin protein was expressed in Escherichia coli strain BL21 (DE3) and purified through Ni-IDA resin affinity chromatography. The Trx-PtDefensin fusion protein displayed no cytotoxic activity against RAW264.7 cells but had cytotoxic activity against E. coli K12D31 cells. Analyses of PtDefensin transcript abundance showed that the expression levels of PtDefensin responded to abiotic and biotic stresses. Overexpression of PtDefensin in 'Nanlin 895' poplars (Populus × euramericana cv 'Nanlin895') increased resistance to Septotis populiperda, coupled with upregulation of MYC2 (basic helix-loop-helix (bHLH) transcription factor) related to jasmonic acid (JA) signal transduction pathways and downregulation of Jasmonate-zim domain (JAZ), an inhibitor in the JA signal transduction pathway. We speculate that systemic acquired resistance (SAR) was activated in non-transgenic poplars after S. populiperda incubation, and that induced systemic resistance (ISR) was activated more obviously in transgenic poplars after S. populiperda incubation. Hence, overexpression of PtDefensin may improve the resistance of poplar plants to pathogens.
植物防御素参与了植物防御系统，但它们在杨树免疫中的作用仍不清楚。本研究表明，PtDefensin（一种假定的植物防御素）参与了杨树植物对Septotis populiperda 感染的防御。在构建重组质粒 PET-32a-PtDefensin 后，PtDefensin 蛋白在大肠杆菌菌株 BL21（DE3）中表达，并通过 Ni-IDA 树脂亲和层析进行纯化。Trx-PtDefensin 融合蛋白对 RAW264.7 细胞没有细胞毒性，但对 E. coli K12D31 细胞具有细胞毒性。PtDefensin 转录物丰度分析表明，PtDefensin 的表达水平对非生物和生物胁迫有响应。在‘南林 895’杨树（Populus×euramericana cv 'Nanlin895'）中过表达 PtDefensin 增加了对Septotis populiperda 的抗性，同时上调了与茉莉酸（JA）信号转导途径相关的 MYC2（碱性螺旋-环-螺旋（bHLH）转录因子），并下调了 JA 信号转导途径中的抑制剂 Jasmonate-zim 结构域（JAZ）。我们推测，在 Septotis populiperda 孵育后，非转基因杨树中激活了系统获得性抗性（SAR），而在 Septotis populiperda 孵育后，转基因杨树中更明显地激活了诱导系统抗性（ISR）。因此，PtDefensin 的过表达可能提高了杨树植物对病原体的抗性。
