MicroRNA转录后调控欧美杨R2R3-MYBs抗锈菌表达

MicroRNA-regulated Compatible Poplar R2R3-MYB Gene Expression Following the Infection of Virulent Melampsora larici-populina

[目的]强致病锈菌亲和型树种欧美杨适合做寄主感病分子机理研究。研究表明转录因子及其调控miRNA在杨树抗/感病过程中起重要的信号传导和调控作用,决定杨树与锈菌的亲和性。为深入研究杨树感病性,对欧美杨R2R3-MYB转录因子及其调控miRNA进行研究。[方法]构建锈菌侵染和未侵染miRNA组、降解组文库和基因表达谱文库,进行高通量测序。对基因表达谱结果进行生物信息学分析鉴定R2R3-MYBs,根据miRNA组和降解组数据确定R2R3-MYBs调控miRNA。应用定量PCR技术鉴定候选R2R3-MYBs和其调控miRNA的表达量。[结果]共鉴定到230个欧美杨R2R3-MYBs,其中55个R2R3-MYBs在锈菌侵染和未侵染叶片间表达量差异显著,其余表达量变化不显著。基于降解组,共鉴定到由22个miRNA调控18个R2R3-MYBs的86个转录后调控关系。定量PCR结果表明PC-3p-2521022_1与Pnd MYB173存在转录后负调控关系。预测的R2R3-MYB靶基因涉及水杨酸、茉莉酸、乙烯和脱落酸等多个植物激素抗性路径。[结论]E4强致病锈菌侵染导致亲和型树种欧美杨23.9%的R2R3-MYBs表达量发生变化,锈菌侵染不但可以影响R2R3-MYBs的表达量,还可以启动或关闭R2R3-MYBs的表达。欧美杨在E4强致病锈菌胁迫条件下,R2R3-MYBs转录后主要受miR159和miR858家族的miRNA调控。

The poplar ‘Robusta’, susceptible to virulent rust E4 Melampsora larici-populina, provides suitable host material for the study of the plant host resistance/susceptibility to pathogen. Previously study indicates that the transcription factor （TF） plays an important role in determining the poplar susceptibility. In this study, the authors tried to determine the R2R3-MYB TF genes driving basal disease resistance and focus on microRNAs （miRNAs） regulation.[Method]Two small RNA （sRNA） libraries, a degradome cDNA library and 2 digital gene expression libraries were constructed for rust-inoculated （Rust＋） and rust-free （Rust-） susceptible poplar ‘Robusta’ leaves through high-throughput sequencing. The expression of selected miRNA and target R2R3-MYBs were identified by RTq-PCR. [Result]Altogether, 230 R2R3-MYBs were identified. Among those R2R3-MYBs, the expression of 55 genes were suppressed/promoted following the drive straight of the rust, the others were unchanged. Based on the miRNA and degradome sequencing, 86 regulating interactions （22 miRNA to 18 R2R3-MYB） were identified. RTq-PCR of selected PC-3p-25210221 and PndMYB173 showed a negative post-transcriptional regulation. The R2R3-MYBs target genes predication indicated R2R3-MYBs related to many resistance and phytohormone pathways, such as response to salicylic acid stimulus, response to stress, response to jasmonic acid stimulus and response to abscisic acid stimulus.[Conclusion]The infection of virulent rust changed the expression of 23.9% R2R3-MYBs. The differential expression of R2R3-MYBs indicated that the rust fungi infection could not only switch on but also switch off R2R3-MYB TF genes. Under the stress of rust infection, the post-transcriptional regulation of R2R3-MYBs was regulated by the families of miR159 and miR858.