转录组分析揭示玉米大斑病菌对解淀粉芽孢杆菌胁迫响应机制

Comparative Transcriptome Analysis of Setosphaeria turcica Revealed its Responses Mechanisms to the Biological Control Agent Bacillus amyloliquefaciens

在植物病害生物防治系统中,生防微生物的生物防治机制是关注的重点,而植物病原物如何响应并抵抗或缓解生防微生物胁迫的机制往往被忽略.本文以解淀粉芽孢杆菌(Bacillus amyloliquefaciens)和玉米大斑病菌(Setosphaeria turcica)为生防互作系统,利用RNA-seq技术研究S.turcica对B.amyloliquefaciens生防胁迫响应的分子机制,结果表明,与对照S.turcica样品比较,B.amyloliquefaciens发酵液处理的S.turcica样品中共有393个基因显著差异表达,其中168个基因上调表达,225个基因下调表达.已知解淀粉芽孢杆菌的抗菌物质一般作用于真菌细胞壁、细胞膜,通过破坏细胞壁及细胞膜的结构抑制真菌生长,因此,本研究在差异表达基因中重点分析S.turcica细胞壁、细胞膜结构相关基因,发现S.turcica上调表达细胞壁组分蛋白(1-6)-beta-D葡聚糖生物合成途径基因、麦角固醇合成途径Delta(14)甾醇还原酶基因、脂肪酸合成酶基因、抗氧化相关的抗坏血酸过氧化物酶基因、谷胱甘肽硫转移酶基因、腺苷三磷酸结合盒转运蛋白基因;下调表达调控细胞凋亡的Metacaspase基因.这说明S.turcica通过调节芽孢杆菌抗菌活性物质的靶标蛋白或合成途径的基因表达,以缓解B.amyloliquefaciens的生防胁迫作用,是一种涉及多个基因和多个信号途径共同参与调控的复杂网络.该研究结果将为研究病原真菌对生防微生物胁迫的抗性机制奠定基础.

The mechanisms of biological control of plant diseases have been intensively studied; however, how plant pathogens respond to and resist or alleviate biocontrol agents remain largely unknown. In the present study, comparative transcriptome analysis was performed to elucidate how the northern corn leaf blight pathogen, Setosphaeria turcica, responds to and resists the biocontrol agent, Bacillus amyloliquefaciens. The results showed that, compared with the control sample of S. turcica, a total of 393 genes were differentially expressed in the sample of S. turcica that was treated with B. amyloliquefaciens fermentation broth. Among these genes, 168 were up-regulated and 225 were down-regulated. Further analysis indicates that various genes related to the fungal cell wall were significantly up-regulated, including（1-6）-beta-D glucan biosynthetic pathway genes, delta（14）-sterol reductase ergosterol biosynthesis pathway genes, fatty acid synthase genes, L-ascorbate peroxidase genes related to oxidative stress, glutathione S-transferase genes, and ABC transporter genes. In contrast, metacaspase genes that regulate apoptosis were significantly down-regulated. These results suggested that S. turcica recruit numerous genes to respond to or resist the biocontrol of B. amyloliquefaciens. The present study provides a valuable resource on the mechanisms of fungal pathogen resistance to biocontrol agents.