油茶根系与内生细菌枯草芽孢杆菌互作早期的转录组分析

Transcriptome Analysis of Camellia olefolia Root and the Endophytic Bacteria Bacillus Subtilis at the Early Stage of Their Interaction

【目的】研究油茶-内生细菌互作早期的油茶根系转录组变化规律,为阐明油茶与内生细菌互作的分子机制提供依据。【方法】构建内生细菌枯草芽孢杆菌1-L-29gfpr与油茶根系互作体系,以不同时间(0、6、12、24 h)的互作体系为研究材料,利用RNA-Seq技术对油茶根部进行转录组测序及分析。【结果】1)转录组测序共产生52958922条序列,约46.1 Gb,差异表达基因10314条(FDR<0.05且|log_(2)FC|>1)。随着互作时间的延长差异表达基因数量呈高-低-高的趋势,接种6 h后差异表达基因数量为6306个,其中显著上调3434个,显著下调2572个;接种12 h后显著上调903个,显著下调526个;接种24 h后显著上调1195个,显著下调1384个。2)GO富集分析表明:接种6 h油茶的生物学过程、分子功能方面变化最为明显,生物学过程中磷酸代谢、含磷化合物代谢、响应激素途径、茉莉酸代谢、响应细菌途径等;分子功能中萜烯合酶活性、双加氧酶活性等;细胞组分中膜固有成分等得到富集。3)KEGG通路分析中差异表达基因主要被富集到碳水化合物代谢、氨基酸代谢、信号转导、环境适应性等通路。接种6 h后富集的代谢通路与12、24 h差异较大,其中差异明显的主要有植物激素合成信号通路、植物病原互作通路、苯丙素生物合成通路。4)基因表达量变化较大的有生长素诱导蛋白编码基因(SAUR)、木葡聚糖内糖基转移酶/水解蛋白酶编码基因(XTH)、茉莉酮酸酯ZIM结构域蛋白编码基因(TIFY)、钙调蛋白编码基因(CAM2)、转录因子MYB编码基因、抗病蛋白编码基因(RPM、RPS)、呼吸爆发氧化酶编码基因(RBOHC)、过氧化物酶编码基因(POD)。【结论】利用活体互作体系对不同时间段内生细菌-油茶互作转录组进行分析表明,内生细菌可刺激植物根系生长,提高抗性,诱导免疫反应,但随后免疫反应逐渐减弱。

【Objective】This study aims to investigate the change pattern of transcriptomics of Camellia olefolia root in the early stage of its interaction with endophytic bacteria,so as to provide reference for clarifying the molecular mechanism of interaction between C.olefolia and endophytic bacteria.【Method】An interaction system between endophytic Bacillus subtilis 1-L-29 and C.olefolia root was constructed.The transcriptomes of the interaction system were sequenced and analyzed by RNA-Seq at different time periods(0,6,12,24 h).【Result】1)The transcriptome sequencing produced a total of 52958922 sequences,about 46.1 Gb,and 10314 differentially expressed genes(FDR<0.05 and|log_(2)FC|>1).With the extension of interaction time,the expression of differentially expressed genes showed a high-low-high trend.The number of differentially expressed genes at 6 h after vaccination was 6306,of which 3434 genes were significantly up-regulated and 2572 were significantly down-regulated.At 24 h,a total of 903 genes were significantly up-regulated,and 526 genes were significantly down-regulated.At 24 h,a total of 1195 genes were significantly up-regulated,and 1384 genes were significantly down-regulated.2)Go enrichment analysis showed that the biological process and molecular function of C.olefolia were changed most obviously after 6 hours of interaction.In the biological process,phosphate metabolism pathway,phosphorus-containing compound metabolism pathway,hormone response pathway,jasmonic acid metabolism pathway,bacterial response pathway,hormone-mediated signal pathway,cell response to hormone stimulation,phenylpropane biosynthesis pathway and so on were enriched.The activities of terpene synthase and dioxygenase in molecular functions were enriched.The membrane and intrinsic components of the membrane were enriched.3)KEGG pathway analysis showed that the differentially expressed genes were mainly enriched into carbohydrate metabolism,amino acid metabolism,signal transduction,environmental adaptability and other pathways.The metabolic pathways enriched at 6 h after inoculation were significantly different from those at 12 h and 24 h,among which the significant differences were mainly plant hormone synthesis signaling pathway,plant pathogen interaction pathway and phenylpropanol biosynthesis pathway.4)The genes with large changes in expression included auxin-inducible protein coding gene(SAUR),xyloglucan endoglycosyltransferase/hydrolytic protease coding gene(XTH),jasmonate ZIM domain protein coding gene(TIFY),calmodulin coding gene(CAM2),transcription factor MYB coding gene,disease resistance protein coding gene(RPM,RPS),respiratory burst oxidase coding gene(RBOHC),peroxidase coding gene(POD).【Conclusion】In this study,for the first time,the living body interaction system has been used to analyze the endophytic bacteria-C.olefolia root interaction transcriptome at different time periods.The results indicate that endophytic bacteria can stimulate plant root growth,increase resistance,and induce immune response,but then the immune response gradually weakens.The results of this study laid a theoretical foundation for the analysis of the molecular mechanism of interaction between endophytic bacteria and C.oleifera.