Analysis of infection process and methylation-sensitive amplified polymorphism in Zea mays genome stressed by Rhizoctonia solani | 玉米纹枯病菌侵染的病理学观察及基因组甲基化敏感扩增多态性分析

Chinese. 植物基因组DNA 甲基化的变化是调节基因功能的重要手段，是生物体应对各种胁迫的表观遗传反应。本研究对玉米(Zea mays)高耐纹枯病材料R15和高感纹枯病材料478进行人工接种纹枯病病菌（Rhizoctonia solani Kühn），利用扫描电镜及数码拍照技术观察病菌侵染自交系R15的病理学变化，结果显示，菌丝主要通过叶鞘部位气孔进行侵染，病斑大小的变化表明病菌对寄主的侵染具有一定的梯度性；利用基因组甲基化敏感扩增多态性(MSAP)技术，采用24对选择性扩增引物对两个抗性不同玉米材料接菌0、6、12和24 h的DNA甲基化模式进行分析，结果显示，两个材料中半甲基化水平均呈上升趋势，且R15变化幅度较大，全甲基化水平呈现先上升后下降的趋势。本研究表明，DNA甲基化与玉米纹枯病抗性反应密切相关，在抗性反应调节系统中可能起重要的作用。

English. Plant genome DNA methylation plays an important role in regulating gene expression and epigenetic change responded to various stresses. In this study, Maize(Zea mays) of high resistance inbred line R15 and high susceptible inbred line 478 were adopted by inoculating sheath blight pathogen (Rhizoctonia solani Kühn), and pathological changes in maize inbred line R15 were observed by electronic microscope and digital camera technology. The result showed that host was infected by mycelium through the leaf sheath stomata and the change of lesion size revealed the pathogen infection on the host has a certain gradient. The patterns of methylation were analyzed in high resistant inbred line R15 and high susceptible inbred line 478 by methylation-sensitive amplified polymorphism (MSAP), which are all inoculated for 0, 6, 12 and 24 h, respectively and amplified by 24 pairs of selective primers. The results showed hemi-methylation level increased but total methylation level first increased and then decreased in both R15 and 478. However, the level of increase in R15 was higher than that of 478. In conclusion, DNA methylation is closely related with maize resistance to Rhizoctonia solani Kühn and plays an important role in regulating gene expression responded to maize resistance.