【作者】 冯瑞瑞；

【导师】 单卫星；

【作者基本信息】 西北农林科技大学 ， 植物病理学， 2018， 硕士

【摘要】 卵菌是一类形态结构上类似于丝状真菌,但是在系统发育上更接近于硅藻、褐藻的不等鞭毛类的真核生物。卵菌的种类多样,占据了多个生态位,其中大部分为植物寄生菌,经常会导致作物减产甚至绝收,对人类生产活动及生态环境造成严重威胁。致病疫霉菌(Phytophthora infestans)、大豆疫霉菌(Phytophthora sojae)和辣椒疫霉菌(Phytophthora capsici)等是造成我国马铃薯、大豆和辣椒等作物生产中的重大病害的病原菌。疫霉菌分泌大量具有RXLR基序的效应蛋白来促进侵染。RXLR效应蛋白进入植物细胞通过调控靶标分子抑制植物免疫系统以促进侵染。因此,研究RXLR效应蛋白作用于植物靶标分子的机制,对解析疫霉菌致病机制至关重要。Avr3a是一个较为保守的效应蛋白,在致病疫霉菌、辣椒疫霉菌和大豆疫霉菌基因组中都存在同源蛋白,组成Avr3a家族效应蛋白。本实验室前期筛选鉴定到一个与Avr3a家族效应蛋白相互作用的靶标——肉桂醇脱氢酶CAD7。本研究通过研究Avr3a家族成员与CAD家族其他成员互作情况,发现CAD5与Avr3a家族成员互作,并进一步分析CAD5的功能,获得以下结果:(1)利用酵母双杂交(Y2H)技术、双分子荧光互补技术(Bi FC)及免疫共沉淀(Co-IP)技术,在拟南芥-辣椒疫霉菌、本氏烟-辣椒疫霉菌、本氏烟-致病疫霉菌3个植物病原互作体系中,证实CAD5与Avr3a家族效应蛋白发生相互作用。(2)利用35S启动子在拟南芥中过表达At CAD5,通过离体叶片接菌辣椒疫霉菌测试,结果表明At CAD5是拟南芥防御相关的正调控因子。(3)利用VIGS技术沉默At CAD5在本氏烟中的直系同源物Nb CAD5,通过离体叶片接种辣椒疫霉菌及致病疫霉菌,结果显示Nb CAD5的沉默促进病菌定殖,CAD5正调控植物对疫霉菌的防御反应。更多还原

【Abstract】 Oomycetes are a group of eukaryotes that are morphologically and structurally similar to filamentous fungi,their true phylogenetic affinity is with diatoms and brown algae in the kingdom Straminipila.Oomycetes are diverse,occupying a number of niches,most of which are plant parasites,and often result in severe losses in crop production,posing a serious threat to human activities and the ecological environment.Phytophthora infestans,P.sojae and P.capsici are notorious pathogens of potato,soybean and pepper,respectively.Phytophthora pathogens secrete numorous effector proteins with a RXLR motif to play a virulence role in promoting infection.Therefore,improved understanding on the modulation mechanism of RXLR effector proteins is essential for developing novel strategies for the prevention and control of plant diseases.Avr3a is an important RXLR effector protein in P.infestans,being relatively conserved across several Phytophthora species,including P.capsici and P.sojae.Avr3 a effector proteins from these Phytophthora species form Avr3 a family effector proteins.Arabidopsis thaliana cinnamyl alcohol dehydrogenase 7(At CAD7)was identified in our previous research as a target of the Avr3 a family effector proteins.In this research,I focus on the interaction between Avr3 a family members and other members of the CAD family proteins and the function of CAD5.The following results were obtained:(1)Multiple approaches with three different compatible pathosystms Arabidopsis-P.capsici,N.benthamiana-P.capsici,and N.benthamiana-P.infestans consistently showed that CAD5(At CAD5 in A.thaliana and its ortholog Nb CAD5 in N.benthamiana)proteins interact with Avr3 a family effector proteins.The three different interaction assays include Yeast two-hybrid system(Y2H),bimolecular fluorescence complementarity(Bi FC),and co-immunoprecipitation(Co-IP).(2)At CAD5 overexpression in A.thaliana and pathogenicity assays showed that At CAD5 is a positive regulator of plant immunity to P.capsici.(3)RNA silencing of the orthologous Nb CAD5 in N.benthamiana by virus induced gene silencing(VIGS)and pathogenicity assays with P.capsici and P.infestans further showed that CAD5 is a positive regulator of plant immunity to Phytophthora pathogens.更多还原