Dual role of the Ustilago maydis GATA transcription factor Nit2 in the control ofpathogenic development and nitrogen utilization during biotrophy

玉米黑粉菌 GATA 转录因子 Nit2 在生物营养过程中控制病原发展和氮利用的双重作用

• 批准号: 421477591
• 负责人: Professor Dr. Lars Voll
• 金额: --
• 依托单位: AG Molekulare Pflanzenphysiologie und Photobiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/421477591?language=en
• 关键词: Dual; role; Ustilago; maydis; GATA

Nitrogen represents the most limiting nutrient in agriculture and it has been shown that biotrophic eukaryotic plant pathogens are specifically adapted to the provision of selected organic nitrogen sources by the host. Successful biotrophic plant pathogens need to establish the provision of assimilates by the colonized host tissue upon penetration, which represent their sole sources of organic carbon and nitrogen. The flexible and efficient utilization of organic carbon and nitrogen sources is the key adaptation of heterotrophic microorganisms to changing environments, which is governed by carbon and nitrogen catabolite repression, CCR and NCR, respectively. Although sensors and regulators of CCR and NCR tend to be conserved in eukaryotic systems, it is only poorly understood how eukaryotic human or plant pathogens adapt to fluctuating availability of nutrients during the progress of infection. Loss of central transcriptional regulators of NCR results in reduced pathogenicity in several (hemi)biotrophic fungal phytopathogens, including the dimorphic basidiomycete Ustilago maydis, the corn smut fungus. U. maydis strains lacking the GATA transcription factor Nit2, a major positive regulator of NCR, exhibit impaired utilization of non-favoured nitrogen sources in saprophytic sporidia as well as hampered activation of filamentous phytopathogenic growth upon host contact, indicating distinct roles for Nit2 at different stages of the U. maydis life cycle. Transcriptome analyses suggest an involvement of Nit2 in the transcriptional network governing the dimorphic switch from saprophytic to pathogenic growth in U. maydis, as well as a role of Nit2 in the control of nitrogen metabolism during biotrophy. The proposed project is set out to unravel the role of Nit2 in the regulation of U. maydis growth and development at different stages of maize infection. First, we aim at resolving the molecular mechanism by which Nit2 integrates into the transcriptional control of early phytopathogenic development by targeted and untargeted approaches. Available data suggests that Nit2 is not just involved in the signalling network that triggers the onset of phytopathogenic growth, but also in the regulation of nitrogen metabolism during biotrophy. In order to better understand the role of Nit2 in host colonization, we will identify Nit2 target genes at different stages of phytopathogenic development in planta. Identification of in planta target genes that respond to the availability of organic nitrogen opens up the potential to investigate (i) the nutritional status of the pathogen in spatiotemporal resolution, (ii) the response of the pathogen to nutrient availability in planta, and (iii) the significance of this response for virulence.

氮代表农业中最具限制性的营养素，并且已经显示活体营养型真核植物病原体特异性地适应于由宿主提供所选择的有机氮源。成功的活体营养型植物病原体需要建立由定殖的宿主组织在渗透时提供同化物，这是它们唯一的有机碳和氮来源。异养微生物对有机碳源和氮源的灵活高效利用是其适应环境变化的关键，其主要机制分别是碳源降解抑制（CCR）和氮源降解抑制（NCR）。虽然CCR和NCR的传感器和调节器在真核系统中趋于保守，但对真核人类或植物病原体在感染过程中如何适应营养物质的波动性知之甚少。NCR的中央转录调节子的丢失导致几种（半）活体营养真菌植物病原体的致病性降低，包括二型担子菌玉米黑粉菌（Ustilago maydis）、玉米黑穗病真菌。联合缺乏加塔转录因子Nit 2（NCR的主要正调控因子）的玉米菌株表现出对腐殖孢子虫中非有利氮源的利用受损，以及在与宿主接触时对丝状植物病原生长的激活受阻，表明Nit 2在玉米不同阶段中的不同作用。玉米生命周期转录组分析表明，Nit2参与了调控U。玉米，以及在氮代谢的控制中的作用，氮2在生物营养。该项目旨在揭示Nit2在调节U。在玉米生长发育的不同时期感染。首先，我们的目标是解决的分子机制，Nit2整合到转录控制的早期植物病原性发展的目标和非目标的方法。现有的数据表明，Nit2不仅参与触发植物病原性生长开始的信号网络，而且还参与生物营养过程中氮代谢的调节。为了更好地了解Nit2在寄主定殖中的作用，我们将在植物病原发育的不同阶段鉴定Nit2靶基因。在植物靶基因的识别，响应有机氮的可用性开辟了潜在的调查（i）时空分辨率的病原体的营养状况，（ii）病原体的响应，营养供应在植物，和（iii）这种响应的毒力的意义。