Department of Biological Sciences; University of Lethbridge; Lethbridge, AB Canada.
Plant Signal Behav. 2013 Jul;8(7):e24760. doi: 10.4161/psb.24760. Epub 2013 Jul 8.
The role of resistance (R) genes in plant pathogen interaction has been studied extensively due to its economical impact on agriculture. Interaction between tobacco mosaic virus (TMV) and the N protein from tobacco is one of the most widely used models to understand various aspects of pathogen resistance. The transcription activity governed by N gene promoter is one of the least understood elements of the model. In this study, the N gene promoter was cloned and fused with two different reporter genes, one encoding β-glucuronidase (N::GUS) and another, luciferase (N::LUC). Tobacco plants transformed with the N::GUS or N::LUC reporter constructs were screened for homozygosity and stable expression. Histochemical analysis of N::GUS tobacco plants revealed that the expression is organ specific and developmentally regulated. Whereas two week old plants expressed GUS in midveins only, 6-wk-old plants also expressed GUS in leaf lamella. Roots did not show GUS expression at any time during development. Experiments to address effects of external stress were performed using N::LUC tobacco plants. These experiments showed that N gene promoter expression was suppressed when plants were exposed to high but not low temperatures. Expression was also upregulated in response to TMV, but no changes were observed in plants treated with SA.
由于其对农业的经济影响，抗性（R）基因在植物病原体相互作用中的作用已被广泛研究。烟草花叶病毒（TMV）与烟草 N 蛋白之间的相互作用是了解病原体抗性各个方面的最广泛使用的模型之一。由 N 基因启动子控制的转录活性是该模型中最不为人知的要素之一。在这项研究中，克隆并融合了 N 基因启动子与两种不同的报告基因，一种编码β-葡萄糖醛酸酶（N::GUS），另一种编码荧光素酶（N::LUC）。筛选转化了 N::GUS 或 N::LUC 报告基因构建体的烟草植物，以获得纯合性和稳定表达。对 N::GUS 烟草植物的组织化学分析表明，表达具有器官特异性和发育调控性。两周龄的植物仅在中脉中表达 GUS，而 6 周龄的植物也在叶片薄片中表达 GUS。在发育过程中的任何时候，根都没有表现出 GUS 表达。使用 N::LUC 烟草植物进行了研究外部应激影响的实验。这些实验表明，当植物暴露于高温而不是低温时，N 基因启动子的表达受到抑制。N 基因启动子的表达也对 TMV 作出反应而上调，但在用 SA 处理的植物中没有观察到变化。
