Gao Ge, Jin Ruibing, Liu Di, Zhang Xin, Sun Xiaomei, Zhu Pengfang, Mao Hongyu
College of Forestry, Shenyang Agricultural University, Shenyang, China.
Key Laboratory of Forest Tree Genetics, Breeding and Cultivation of Liaoning Province, Shenyang, China.
Front Plant Sci. 2022 Apr 27;13:865607. doi: 10.3389/fpls.2022.865607. eCollection 2022.
Chrysanthemum white rust (CWR), a disease caused by the fungus Henn., seriously impairs the production and ornamental value of chrysanthemums. We previously isolated the disease-resistance gene from the chrysanthemum and generated transgenic plants. Here, we determined that -overexpressing lines of the susceptible cultivar 'Jinba' show higher defensive enzyme activity and lower HO levels than a wild type after inoculation with , indicating that positively regulates plant responses to . To further explore the mechanism underlying this effect, we performed RNA sequencing using the leaves of wild-type and -RNA interference lines of the resistant cultivar 'C029' after treatment with . We identified seven differentially expressed genes in the salicylic acid (SA) pathway, including (), encoding an important regulator of this pathway. We isolated the promoter by hiTAIL-PCR and predicted that it contains pathogen-induced W-box elements. The promoter region of was activated by in a β-glucuronidase activity assay. Yeast one-hybrid assays showed that CmWRKY15-1 binds to the promoter region to regulate its expression. Finally, we confirmed the interaction between CmWRKY15-1 and CmNPR1 in a bimolecular fluorescence complementation assay. We propose that CmWRKY15-1 interacts with CmNPR1 to activate the expression of downstream pathogenesis-related genes that enhance resistance to through the SA pathway. These findings shed light on the mechanism underlying resistance to CWR.
菊花白锈病（CWR）是由真菌柄锈菌引起的一种病害，严重损害菊花的产量和观赏价值。我们之前从菊花中分离出抗病基因并培育出转基因植株。在此，我们测定了感病品种‘津巴’的过表达株系在接种柄锈菌后比野生型表现出更高的防御酶活性和更低的过氧化氢水平，表明该基因正向调控植物对柄锈菌的反应。为进一步探究其作用机制，我们对接种柄锈菌处理后的抗病品种‘C029’的野生型和该基因RNA干扰株系的叶片进行了RNA测序。我们在水杨酸（SA）途径中鉴定出7个差异表达基因，包括编码该途径重要调控因子的基因。我们通过热不对称交错PCR（hiTAIL-PCR）分离出该基因的启动子，并预测其含有病原体诱导的W盒元件。在β-葡萄糖醛酸酶活性测定中，该基因的启动子区域被柄锈菌激活。酵母单杂交试验表明，CmWRKY15-1与该基因的启动子区域结合以调控其表达。最后，我们在双分子荧光互补试验中证实了CmWRKY15-1与CmNPR1之间的相互作用。我们提出，CmWRKY15-1与CmNPR1相互作用，通过SA途径激活下游病程相关基因的表达，从而增强对柄锈菌的抗性。这些发现揭示了菊花抗白锈病的潜在机制。
