【作者】 张绍鹏；

【导师】 郑用琏；

【作者基本信息】 华中农业大学 ， 生物化学与分子生物学， 2012， 博士

【摘要】 玉米丝黑穗病是由玉米丝轴黑粉菌(Sporisorium reilianum f. sp. zeae)引起的严重威胁玉米产量的真菌病害。玉米丝轴黑粉菌在玉米苗期通过胚根的侵染进入到寄主体内,随后在玉米生长的几乎整个生育期内,长期潜伏于植株体内与寄主共存,直到抽雄期,典型的黑粉病症才会在玉米雄穗和雌穗上呈现出来。本研究以抗、感差异明显的玉米自交系Mo17和黄早四为实验试材,从转录水平上探究玉米在抵御玉米丝轴黑粉菌的苗期侵染和后期扩展过程中的基因表达差异和动态,旨在从转录组学的层面上较为系统地了解玉米全生育期抵御丝轴黑粉菌的分子机理。研究工作取得如下初步结果：(1)采用基于双酶切的数字基因表达谱技术(DGE)分析了高感材料黄早四和高抗材料Mo17的主胚根在接种病原菌后的不同侵染状态下,相关基因在转录水平上的表达变化。研究结果表明：在胚根受到的病原菌不同入侵状态下,玉米的病程相关基因在抗、感材料之间的表达模式呈现显著的表达差异；在抗、感材料分别被接种前、后的胚根中,谷胱甘肽S-转移酶的酶活变化和活性氧的积累水平也表现出显著的差异；在抗、感材料分别被接种六天后的胚根中,木质素总含量和沉积模式也表现出了显著不同的动态变化。(2)采用46K的70mer玉米寡聚核苷酸芯片平台,对接种后被病原菌入侵、潜伏并与共存的高抗材料Mo17,在四个典型的发育时期的基因转录水平的动态变化进行了表达研究。结果表明：在Mo17的发育进入到第八叶期之前,寄主和病原菌之间一直维系一种共生共存的“和谐”关系,直到进入到玉米从营养生长向生殖生长转换的过渡时期,高感材料黄早四中潜伏的菌丝会大量的分支扩增从而产生病症,而高抗材料Mo17则可以通过诱发相关基因的表达,提高黄酮类物质的积累,对生长素运输和菌丝的分支扩增进行抑制,从而表现出对体内菌丝的扩增和病症的爆发产生抗性。更多还原

【Abstract】 The head smut fungus in maize, Sporisorium reilianum f. sp. zeae, which is an important biotrophic pathogen responsible for extensive crop losses, infects maize by invading the root during the early seedling stage. Head smut is not obvious until the tassels and ears emerge. S. reilianum has a very long life cycle that spans almost the entire developmental program of maize after the pathogen successfully invades the root.In order to investigate disease-resistance mechanisms at this early seedling stage, digital gene expression (DGE) analysis, which applies a dual-enzyme approach, was used to identify the transcriptional changes in the roots of Huangzao4(susceptible) and Mo17(resistant) after root inoculation with S. reilianum. During the infection in the roots, the expression pattern of pathogenesis-related (PR) genes in Huangzao4and Mo17were significantly differentially regulated at different infection stages. The glutathione S-transferase (GST) enzyme activity and reactive oxygen species (ROS) levels also showed changes before and after inoculation. The total lignin contents and the pattern of lignin depositions in the roots differed during root colonization of Huangzao4and Mo17.In order to understand how this pathogen interacts with the host during its long life cycle at the molecular level, and how this interaction differs between susceptible and resistant varieties of maize after hyphal invasion, the maize70mer-oligonucleotide microarrays were used to investigated transcriptional changes in the resistant maize line Mo17at four developmental stages. We found that there was a lengthy compatible relationship between the pathogen and host until the early8th-leaf stage. The resistance in Mo17relied on the assignment of auxin and regulation of flavonoids in the early floral primordium during the early floral transition stage. We propose a model describing the putative mechanism of head smut resistance in Mo17during floral transition. In the model, the synergistic regulations among auxin, flavonoids, and hyphal growth play a key role in maintaining compatibility with S. reilianum in the resistant maize line.更多还原