flg22诱导的拟南芥转录组分析及芥子油苷代谢途径的变化

Transcriptome Analysis of Arabidopsis thaliana and Changes of Glucosinolates Metabolism Pathway Induced by Flg22

flg22是细菌鞭毛蛋白N端的一段保守性极高的区域,能够诱导植物天然的免疫反应,为全面了解植物在受到细菌性病原菌侵害后的系统响应,利用Illumina Hiseq2000对flg22处理和未处理的拟南芥幼苗进行转录组测序。对两组数据进行差异表达分析,共获得1 200个差异表达基因,包括290个下调基因和910个上调基因。对差异表达基因进行GO富集分析和KEGG pathway富集分析,结果显示,flg22处理后,拟南芥在能量代谢、氨基酸代谢及次生代谢产物的生物合成等方面产生了巨大变化。芥子油苷是一类在植物防御病原菌的天然免疫反应中起重要作用的次生代谢产物,因此对芥子油苷代谢途径的变化进行了深入分析。根据测序结果,Flg22处理后吲哚族芥子油苷合成途径的基因表达水平显著提高,而脂肪族芥子油苷代谢途径几乎没有变化,进一步对吲哚族芥子油苷合成途径的关键酶基因进行Real Time RT-PCR的分析,验证了测序结果的正确性,证明了吲哚族芥子油苷在植物抗病防御反应中的重要作用。这为深入理解病原菌诱导的植物防御性反应及吲哚族芥子油苷的抗病机制提供了大量参考数据。

Flg22 is a highly conserved amino acid sequence in the N terminal of bacterial flagellum protein, which can induce plant natural immune response. In order to fully understand systemic responses of plant to bacterial pathogens, two sequencing libraries of Arabidopsis seedlings treated and not treated with flg22 were constructed and sequenced using Illumina Hiseq2000. Comparison of the two samples showed 1 200 differentially expressed genes （DEGs）, including 290 down-regulated and 910 up-regulated genes. GO functional enrichment and KEGG pathway enrichment analysis revealed that the DEGs were associated with energy metabolism, amino acid metabolism and biosynthesis of secondary metabolites. Glucosinolates are important secondary metabolites involved in innate immune response against pathogen, therefore it is of necessary to analyze glucosinolates metabolism pathway. After flg22 treatment, genes involved in indolic glucosinolate biosynthesis pathway were up-regulated significantly,which is further demonstrated by Real Time RT-PCR, while aliphatic glucosinolate pathway almost had no change, indicating the important role of indolic glucosinolates in plant defense responses. This research provided numerous genetic data to deeply understand pathogen induced defense and the contribution of indolic glucosinolates.