Specific communication processes of distinct conidia types during germination, early colony development, and host plant infection of the fungal maize pathogen Colletotrichum graminicola

在过去的二十年中，关于丝状真菌引起的植物感染爆发的报道增加，包括玉米，小麦，水稻和马铃薯等重要作物。禾生炭疽菌（Colletotrichum graminicola）是玉米炭疽病的病原菌，仅在美国每年的经济损失就达10亿美元。在感染过程中，两种特定的感染性真菌孢子类型调节中央致病过程。在感染的叶片上形成的镰刀形分生孢子分泌真菌孢子素衍生物到周围的粘液中。这些信号分子依赖于营养物和孢子密度抑制这种孢子类型的萌发。另一方面，椭圆形分生孢子产生信号，使年轻的胚芽协调融合。有趣的是，这两种孢子特异性信号从根本上影响这种玉米病原体的感染策略。由于这两种分泌信号在另一种孢子类型中都不存在，我们将试图解开外部刺激，生物合成和这些孢子特异性信号的详细功能。禾生菌 菌孢菌素是参与保护免受紫外线辐射的次级代谢产物，如氧化和渗透胁迫。在前期的实验中，我们发现蓝藻中与菌孢菌素生物合成有关的同源基因在C.禾生菌使用计算机模拟分析，我们进一步能够确定一个推定的次级代谢产物簇，在这种真菌中产生的真菌孢菌素。在结合特定的菌孢素衍生物的功能研究的方法中，我们将寻求确定在C.本发明涉及应用RNAseq、缺失突变体的遗传和表型分析的禾生单胞菌。基于这些发现，我们的目标是解开这些次生代谢产物的作用，孢子特异性的生活史和致病性的植物病原体。 营养细胞融合体的形成是丝状子囊菌中高度保守的过程。预计该过程通过优化营养物质的可用性和协调发育过程和生长模式来增加真菌菌落的适合度。在融合形成过程中，未来融合伴侣的细胞对话发生了：两个伴侣以交替的方式分泌一种未知的信号，引导相应的伴侣走向彼此。为了便于融合信号的识别，我们建立了一个管道，包括信号产生，隔离和评估的方法。基于这条管道，我们将应用分析方法比较椭圆形和镰刀形分生孢子产生的分泌物，以确定相应的信号，通过HPLC/MS分析。此外，我们将使用缺失突变体的遗传和表型分析来验证所获得的结果。这将另外允许确定融合信号作为C的可能毒力因子的影响。禾生菌

Within the last two decades, reports on outbreaks of plant infections caused by filamentous fungi increased, including important crop plants like corn, wheat, rice, and potato. Colletotrichum graminicola is the causal agent of corn anthracnose, a disease with the annual economic potential of about 1 billion US dollars only in the USA. During infection, two specific infectious fungal spore types regulate central pathogenicity processes. Falcate-shaped conidia formed on infected leaves secrete mycosporine derivatives into the surrounding mucilage. These signaling molecules inhibit the germination of this spore type in dependence of nutrients and spore density. Oval conidia, on the other hand, generate signals allowing the coordinated fusion of young germlings. Intriguingly, both spore-specific signals fundamentally influence the infection strategy of this maize pathogen. Since both secreted signals are absent from the other spore type, we will seek to unravel external stimuli, biosynthesis, and detailed functions of these spore-specific signals of C. graminicola. Mycosporines are secondary metabolites involved in protection from UV-radiation alike as oxidative and osmotic stress. In our pre-experiments we have found that homologous genes of the mycosporine biosynthesis in cyanobacteria are expressed in a tissue-dependent way in C. graminicola. Using in silico analyses, we were further able to identify a putative secondary metabolite cluster for the generation of mycosporines in this fungus. In an approach combining functional studies of specific mycosporine derivatives, we will seek to identify the biosynthesis pathways of mycosporines in C. graminicola applying RNAseq, genetic, and phenotypic analyses of deletion mutants. Based on these findings we aim to unravel the role of these secondary metabolites in spore-specific life-cycle and pathogenicity of this plant pathogen. Formation of vegetative cell fusions is a highly conserved process in filamentous ascomycetes. It is anticipated that this process increases the fitness of a fungal colony by optimizing nutrient availability and coordinating developmental processes and growth patterns. During the fusion formation, a cellular dialog of the future fusion partners takes place: both partners secrete a yet unknown signal in an alternate fashion, guiding the corresponding partners towards each other. To facilitate the identification of the fusion signal, we established a pipeline including methods for signal generation, isolation, and evaluation. Based on this pipeline we will apply analytical methods comparing the secretomes generated by oval and falcate conidia to identify the corresponding signal by HPLC/MS analyses. Further, we will verify the obtained results using genetic and phenotypical analyses of deletion mutants. This will additionally allow determining the impact of the fusion signal as a probable virulence factor of C. graminicola.