Cloning and characterization of the PtVIP1 gene in Populus

The VirE2-interaction protein 1(VIP1)serves as a regulator of mitogen-activated protein kinase 3(MPK3)-mediated stress gene modulation under biotic stress,which in turn activates the MPK3 pathway in Arabidopsis.The mode of action of the VIP1 protein in Populus in response to biotic stress remains unknown.In this study,we cloned the full-length cDNA of the PtVIP1 gene from Populus trichocarpa(accession number of GenBank:KY793105).The VIP1 protein harboured a conserved bZIP(basic leucine zipper)domain located in the C-terminus.The VIP1 subcellular localization assay indicated that the VIP1 protein was present in the cytoplasm and nucleus under normal conditions,and that an increase in the amount of the protein in the nucleus occurred after treatment with flg22,the elicitor-active epitope of flagellin which triggers the innate immune response in plants.Transgenic Populus plants overexpressing VIP1 genes(PtVIP1 of Populus;or AtVIP1 of Arabidopsis,as positive control)were generated to investigate the role of VIP1 in vivo.The expression of poplar pathogenesis-related protein 1(PR1)genes was upregulated in transgenic-PtVIP1 or AtVIP1 poplar plants.The transgenic poplar plants overexpressing PtVIP1 or AtVIP1 also showed enhanced resistance to Brenneria salicis infection.These results suggest that the VIP1 protein accumulates in the nucleus in response to biotic stress,and that the pathogen resistance of transgenic VIP1 poplar may be associated with the induced expression of PR1 genes in response to pathogen challenge.

Natural infectious behavior of the urediniospores of Melampsora larici-populina on poplar leaves

The uredinial stage in the life cycle of Melampsora larici-populina on poplar leaves is the most important pathogenic phase. We captured partial phases of uredinial infection in the wild, aiming to reconstruct the process of uredinial ontogeny by using scanning and transmission electron microscope. At the initial infection stage, germ tubes germinated from the echinulate urediniospores. Germ tubes were frequently seen to merge with the leaf surface and cuticle breakage was observed, indicating direct hyphal penetration. Stomata penetration occurred commonly, sometimes with more than one germ tube penetrating the same stoma. Melampsora larici-populina did not form appressoria in the infection process,implying that infectious behavior of this pathogen may differ from the other rust pathogens. In general, germ tubes branched randomly, and no distinct evidence indicated that stoma could induce or orient germ tube branches. However, oriented germ tube growth has been occasionally observed in other studies. The urediniospores collapsed and finally wizened when they became nutrient stressed. At the last stage of infection, the uredinia erupted from the leaf epidermis and appeared as orange pustules on the leaf surface.

基于已知顺式元件的人工启动子响应性分析揭示烯丙异噻唑诱导系统可触发植物体内多条信号途径（英文）

目的:构建有效响应烯丙异噻唑(PBZ)诱导的人工合成启动子,了解植物体内受PBZ诱导系统触发的信号途径。创新点:通过分析包含已知顺式元件的人工合成启动子对PBZ的响应性,为构建一种基于PBZ诱导系统的新型化学诱导启动子提供了可能性,并初步揭示了除水杨酸(SA)外,茉莉酸(JA)和乙烯等多条信号途径可能共同参与了PBZ诱导的植物免疫反应过程。方法:利用已知的响应相关信号通路的顺式作用元件构建人工合成启动子,融合GUS报告基因后,稳定转化拟南芥。通过检测PBZ处理过程中GUS酶活性的变化,了解人工合成启动子对PBZ的响应性,分析PBZ诱导系统可能触发的信号途径。结论:除了SA响应元件SARE可以有效响应PBZ诱导外,利用JA和乙烯响应元件JERE和GCC,超敏反应(HR)相关的顺式元件HSRE和GST1,以及植物抗病反应中重要顺式作用元件W-box构建的人工合成启动子也均可有效响应PBZ。另外,通过人工合成启动子响应性分析的手段,初步揭示了包括SA、JA、乙烯、钙离子和丝裂原活化蛋白激酶(MAPKs)在内的多条信号通路可能共同参与了PBZ诱导植物免疫反应的过程。