赖氨酸-组氨酸转运蛋白1在黄瓜花叶病毒侵染玉米过程中的作用研究

Resistance genes mediated plant immunity is one of the most important antiviral mechanisms. It is of great theoretical and practical importance to screen and identify the resistance genes and illuminate the roles they play during virus infection. In our preliminary results, we identified the resistance gene Lysine histidine transporter 1（LHT1） for Cucumber mosaic virus （CMV） infection from the Arabidopsis mutants library through forward genetics screens and found that it showed recessive resistance during the infection. LHT1 is an important functional gene which participates in the amino acid transport and helps to maintain amino acid homeostasis. In addition, LHT1 is also involved in formatting disease symptoms and has been verified as the resistance locus rhm1 against Southern corn leaf blight. The roles of LHT1 in the infection of maize by CMV will be investigated by using over-expression of LHT1 in maize protoplasts and utilizing the maize H95rhm and H95, transcriptome sequencing will be performed to reveal the correlation between LHT1 and some known resistance pathway, other amino acid homeostasis associated genes will be determined if they are relevant to CMV infection. As a result, these efforts should be helpful to elucidate the resistance mechanism of LHT1 to CMV and provide the foundation for controlling virus disease by plant breeding.

抗性基因介导的免疫反应是植物抗病毒侵染的重要手段之一。筛选和鉴定抗性基因并解析其在病毒侵染中的作用机制具有重要的理论和现实意义。我们在前期的研究中利用正向遗传学的方法从拟南芥突变体库中筛选到了抗黄瓜花叶病毒（CMV）侵染的抗性基因赖氨酸-组氨酸转运蛋白1（LHT1），并证明LHT1在拟南芥抗CMV中具有隐性抗性。LHT1是参与氨基酸转运并维持植物体内氨基酸稳态的重要基因，LHT1还参与病害症状的形成，是玉米小斑病的重要抗性基因rhm1。我们将通过原生质体过量表达、利用玉米种质材料H95rhm及H95等方式研究LHT1在CMV侵染玉米中的功能；通过转录组测序研究玉米中LHT1基因与其它抗性途径的相关性，通过研究其他与氨基酸稳态相关的基因与CMV侵染的相关性，阐明LHT1在CMV侵染过程侵染过程中的抗性机制，为抗病育种提供理论依据。

抗性基因介导的免疫反应是植物抗病毒侵染的重要途径之一。在前期的研究中利用正向遗传学方法筛选到抗黄瓜花叶病毒（cucumber mosaic virus，CMV）的隐形抗性基因赖氨酸-组氨酸转运蛋白1（LHT1），但是其作用机制仍不清楚。本课题在此基础上，从LHTs相关基因在玉米侵染CMV后转录水平的变化、LHT的亚细胞定位、氨基酸代谢相关基因与CMV侵染的相关性以及LHTs抗病的广谱性等方面系统分析LHTs在CMV侵染中的作用。所取得的结果主要包括：（1）通过进化树分析等表明玉米中的ZmLHT2-2与AtLHT1具有最大的序列相似性并且其在CMV侵染玉米后在转录水平有明显的下调表达；（2）通过瞬时表达的方式表明ZmLHT2-2在烟草表皮细胞及玉米叶片中均定位于细胞膜中；（3）定量分析表明与氨基酸稳态相关的重要基因ZmGDU1在CMV侵染后在转录水平显著下调，ZmAAC的表达也具有显著的变化；（4）通过分析转录组数据表明LHTs同源基因以及参与氨基酸稳态的关键基因在玉米褪绿斑驳病毒及玉米褪绿斑驳病毒和甘蔗花叶病毒混合接种后在转录水平具有明显变化。以上研究结果表明LHTs家族基因在CMV侵染过程中发挥重要功能，同时阐明了氨基酸稳态与病毒侵染具有相关性，为抗病育种提供一定的理论支持。