Toxic metal tolerance of Arabidopsis arenosa inoculated with fungal endophyte Mucor sp. Gene expression study

To determine the mechanisms of improved toxic metal tolerance of A. arenosa inoculated with Mucor sp. whole gemone microarray profiling was employed. Metal toxicity altered the expression of 5169 probe sets; 2861 genes were up-regulated and 2308 down-regulated. Inoculation with the fungi induced changes in the expression of 899 probes from the above presented data set; 492 genes were up-regulated and 314 were down-regulated. The expression of 93 genes (63 and 30, up and down-regulated respectively) was affected by both treatments (Fig. 5A-B). Genes differentially expressed in E+ plants vs E- from mine dump substrate were subject to GO analysis (gene ontology) to identify enriched terms with a cut-off rate of 0.01. The majority of the genes upregulated belonged to ROS metabolism, response to biotic and abiotic stimuli, response to ion starvation and ET biosynthesis and signaling functional categories. Among down-regulated transcripts GO analysis revealed a significant enrichment in the regulation of anthocyanin biosynthesis term. Gene expression profiles of roots of A. arenosa inoculated at 2 leaf seedling stage (10 days after germination), grown in substrate from the “Bolesław”(Poland, (50°16'58"N 19°32'9"E) mine dump, polluted with Zn, Cd, Fe and Pb, not inoculated grown in the same substrate and plants not inoculated grown in commercially available soil were compared. In order to distinguish between the effect of fungi colonization and toxic metal stress on the plants transcriptome, we compared global gene expression of E- plants cultivated in control substrate (commercially available soil mixed with sand in a 2:1 v:v ratio) with E- A. arenosa grown in substrate from the mine dump. Subsequently, the obtained data set was compared to the gene expression profile of Mucor sp. inoculated plants grown in the toxic metal enriched environment (mine dump substrate).

为探究接种毛霉（Mucor sp.）后高山拟南芥（A. arenosa）对有毒金属耐受性提升的分子机制，本研究采用全基因组微阵列分析（whole genome microarray profiling）技术。金属胁迫可改变5169个探针组的基因表达，其中2861个基因上调，2308个基因下调。接种该真菌可导致上述数据集内899个探针的表达发生改变，对应492个基因上调、314个基因下调。共有93个基因（上调、下调分别为63个和30个）的表达同时受到两种处理的影响（图5A-B）。本研究对矿渣基质中带内生真菌的植株（E+）与未定植植株（E-）间的差异表达基因开展基因本体（Gene Ontology, GO）富集分析，筛选阈值设为0.01。上调表达的基因主要富集于活性氧（Reactive Oxygen Species, ROS）代谢、生物与非生物胁迫响应、离子饥饿响应以及乙烯（Ethylene, ET）生物合成与信号转导等功能类别。下调表达的转录本经GO分析后，显著富集于花青素生物合成调控功能条目。本研究对三组高山拟南芥（A. arenosa）的根系基因表达谱进行了比较：其一为于2叶龄幼苗期（萌发后10天）接种毛霉，并种植于波兰博莱斯瓦夫（50°16'58"N 19°32'9"E）受锌（Zn）、镉（Cd）、铁（Fe）、铅（Pb）污染的矿渣基质的植株根系；其二为未接种毛霉、种植于上述矿渣基质的植株根系；其三为未接种毛霉、种植于商品土壤的植株根系。为区分真菌定植与有毒金属胁迫对植物转录组的独立影响，本研究将种植于对照基质（商品土壤与沙土按2:1体积比混合）的未定植植株（E-），与种植于矿渣基质的未定植高山拟南芥（E-）的全局基因表达进行了对比。随后，将所得数据集与种植于有毒金属富集环境（矿渣基质）的毛霉接种植株的基因表达谱进行了比对分析。