摘要
本研究以毛白杨(Populus tomentosa)和外生菌根(ectomycorrhizae, ECM)真菌——美味牛肝菌(Boletus edulis)为试验材料,设计两种模拟ECM早期共生阶段进行信号分泌、传导与识别的水培互作试验体系,分析其对候选共生相关基因表达的影响。在信号传导模拟体系中,根系4种基因(SOD、POD、PAL和APX)的表达呈缓慢上升趋势,与真菌侵染模拟体系中的表达趋势一致,说明该体系下的ECM真菌能够分泌水溶性信号因子,有效地诱导寄主共生相关基因上调表达,初步验证了信号传导模拟体系对研究ECM早期信号事件的可行性和有效性。在信号传导模拟体系的基础上,分析菌-根共生信号液以及毛白杨根系分泌物、真菌分泌物的水溶液对根系SOD、POD和CIPK2基因转录水平的影响。结果表明,信号液对CIPK2基因表达上调的诱导最为迅速,呈"双高峰"的形式保持基因表达的上调趋势; SOD基因的转录水平于12 h时呈现单峰;而POD基因的表达量在整个互作期间均处于上调状态,并且上调幅度大。通过对比分析推测,在菌-根互作体系中,双方通过信号因子的交流而感知彼此的存在后,分泌并传递水溶性共生信号,寄主感知真菌源共生信号后启动自身免疫机制,提高防御基因的表达。
In this study, Populus tomentosa and ectomycorrhizae(ECM) Boletus edulis were used as experimental materials to design two systems. In the signal transduction simulation system, the expression of four genes(SOD, POD, PAL and APX) in roots showed a slow upward trend, which was consistent with the expression trend in the fungal infection simulation system, indicating that the ECM fungi in this system could secrete water-soluble signal factors and effectively induce host symbiosis. On the basis of the signal transduction simulation system, the fungal-root symbiotic signal solution and the aqueous solution of root exudates and fungal secretions of P. tomentosa were collected and compared, and the effects on the transcription levels of SOD, POD and CIPK2 genes in roots were compared and analyzed. The up-regulation of CIPK2 expression was the most rapid, and the expression of gene expression was up-regulated as a "double peaks" mode. The transcription of SOD gene was expressed after 12 hours. While the expression level of POD gene was up-regulated during the whole interaction period, and the up-regulation range was significant. Through comparative analysis, it is believed that in the mutual system of fungal-roots, the two sides perceive each other through the communication of signal factors, secrete and transmit water-soluble symbiotic signals. Then, the host senses the symbiotic signal of the fungal source to initiate the autoimmune mechanism and improve the expression of defense gene.
引文
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