中文摘要：

【目的】确定玉米大斑病菌（Setosphaeria turcica）黑色素合成酶基因St PKS、St3HNR、St4HNR、St SCD、St LAC1、St LAC2在基因组中的位置和基因结构,分析黑色素合成途径中6个合成酶基因在玉米大斑病菌侵染过程中从分生孢子萌发至穿透不同时期及菌丝生长时期的表达模式,明确6个基因与病菌发育和致病的关系。【方法】利用玉米大斑病菌基因组数据库,通过Blastp相似性搜索,鉴定6个基因在基因组中的定位,解析在基因组中的串联分布情况;收集玉米大斑病菌从分生孢子萌发到侵染的不同时期及菌丝生长时期的菌体材料,提取总RNA,以β-tubulin作为内参基因,根据黑色素合成6个关键酶基因序列设计引物,采用q RT-PCR技术检测基因的表达模式,对比病菌在营养生长和生殖生长时期的表达情况。【结果】在基因组数据库中,玉米大斑病菌黑色素合成酶基因St PKS、St3HNR分别位于scaffold12的正链和负链上,St4HNR、St LAC2位于scaffold11的负链上,St SCD位于scaffold1正链上,St LAC1位于scaffold7正链上,且St PKS和St3HNR在基因组中串联分布在26.9 kb范围内;6个基因的相对表达量在分生孢子诱导萌发到穿透过程的5个时期中呈上调-下调-上调或上调-下调-上调-下调两种模式;分生孢子时期,St LAC2表达量最高,明显高于其他基因,差异极显著;菌丝生长时期,St3HNR、St SCD表达量最高,明显高于其他基因,差异极显著。【结论】玉米大斑病菌6个黑色素合成酶基因中St PKS和St3HNR在基因组中位置邻近,串联在26.9 kb范围内;6个基因从分生孢子萌发至侵染的5个时期均有表达,表达量存在显著差异,但各基因的表达模式相似,说明6个基因参与了玉米大斑病菌的侵染过程,在玉米大斑病菌的致病方面具有重要作用;同时在菌丝生长时期St3HNR和St SCD发挥的作用更明显,分生孢子时期St LAC2更活跃。

英文摘要：

【Objective】The objectives of this study are to determine the location in the genome, and to investigate the structure of melanin biosynthesis genes St PKS, St SCD, St3 HNR, St4 HNR, St LAC1 and St LAC2 of Setosphaeria turcica. Furthermore, to elucidate the relationship between melanin biosynthesis enzyme genes and morphogenesis and pathogenicity of S. turcica via analyzing the expression pattern of six genes during infection progress from conidial germination to penetration and the mycelia growth period.【Method】 Based on the S. turcica genome database and genome searching with Blastp, the locations of six genes were identified and genes linkage were analyzed. Primers were designed according to the six melanin synthesis enzyme gene sequences. q RT-PCR system was used to detect the six genes expressions of S. turcica, in which total RNAs from different infectious morphogenesis stages including conidial germination to penetration were extracted and used as templates and β-tubulin as the reference gene, and the expression patterns between vegetative and reproductive growth stages were compared.【Result】In genome database, the St PKS and St3 HNR were located on the positive and negative strand of scaffold12, respectively. St4 HNR and St LAC2 were on the negative strand scaffold11. St SCD and St LAC1 located on the positive of strand scaffold1 and scaffold7, respectively. Furthermore, St PKS and St3 HNR were clustered within the 26.9 kb chromosomal region. Relative expression of six genes had two expression profiles, which was up-down- up regulation or up- down- up- down regulation at five stages from conidial germination to penetration. The St LAC2 had the highest expression in conidia, and there was a significant difference in expression. However, St3 HNR and St SCD had a higher expression level than other genes in mycelia.【Conclusion】St PKS and St3 HNR in melanin biosynthesis were clustered within a 26.9 kb chromosomal region. Six genes were whole expressed at five stages from conidial germination to