Transcriptome analyses during fruiting body formation in Fusarium graminearum and Fusarium verticillioides reflect species life history and ecology. Transcriptome analyses during fruiting body formation in Fusarium graminearum and Fusarium verticillioides reflect species life history and ecology

Fusarium graminearum and F. verticillioides are devastating cereal pathogens with very different life history and ecological characteristics. F. graminearum is homothallic, and sexual spores are an important component of its life cycle, responsible for disease initiation. F. verticilloides is heterothallic, and produces only modest numbers of fruiting bodies, which are not a significant source of inoculum. To identify corresponding differences in the transcriptional program underlying fruiting body development in the two species, comparative expression was performed, analyzing six developmental stages. To accompany the transcriptional analysis, detailed morphological characterization of F. verticillioides development was performed and compared to a previous morphological analysis of F. graminearum. Morphological development was similar between the two species, except for the observation of possible trichogynes in F. verticillioides ascogonia, which have not been previously reported for any Fusarium species. Expression of over 9000 orthologous genes were measured for the two species. Functional assignments of highly expressed orthologous genes at each time-point revealed the majority of highly expressed genes fell into the ‘‘unclassified proteins’’ category, reflecting the lack of characterization of genes for sexual development in both species. Simultaneous examination of morphological development and stage-specific gene expression suggests that degeneration of the paraphyses during sexual development is an apoptotic process. Expression of mating type genes in the two species differed, possibly reflecting the divergent roles they play in sexual development. Overall, the differences in gene expression reflect the greater role of fruiting bodies in the life cycle and ecology of F. graminearum versus F. verticillioides. Overall design: mRNA were sampled and compared from six time points across sexual reproduction in two Fusarium species

禾谷镰孢（Fusarium graminearum）与轮枝镰孢（Fusarium verticillioides，原文缩写F. verticillioides）是极具破坏性的谷类病原菌，二者的生活史与生态特征差异显著。禾谷镰孢为同宗配合（homothallic）菌，其有性孢子是生活史的重要组成部分，负责病害的初始侵染。轮枝镰孢则为异宗配合（heterothallic）菌，仅能产生少量子实体，且子实体并非重要的初侵染源。
为探究两个物种在子实体发育背后的转录调控程序中的对应差异，研究开展了比较转录组分析，对六个发育阶段的样本进行了检测。
为配合转录组分析，研究人员对轮枝镰孢的发育过程开展了详细的形态学表征，并将其与此前针对禾谷镰孢的形态学分析结果进行对比。结果显示，两个物种的形态发育整体相似，但在轮枝镰孢的产囊体中观察到了疑似受精丝（trichogynes）的结构，这是此前在任何镰孢属（Fusarium）物种中均未被报道过的现象。
研究对两个物种的超过9000个直系同源基因（orthologous genes）的表达量进行了测定。对每个时间点高表达的直系同源基因进行功能注释后发现，绝大多数高表达基因归为"未分类蛋白"类别，这反映出两个物种中参与有性发育的基因均缺乏相关功能表征。
同时对形态发育与阶段特异性基因表达的联合分析表明，有性发育过程中侧丝（paraphyses）的降解属于细胞凋亡（apoptotic）过程。两个物种的交配型基因（mating type genes）表达模式存在差异，这可能反映了二者在有性发育中发挥的功能有所分化。
总体而言，基因表达的差异体现出，相较于轮枝镰孢，子实体在禾谷镰孢的生活史与生态系统中发挥的作用更为关键。
整体实验设计：采集两个镰孢属物种有性生殖过程中六个时间点的mRNA样本并进行比较分析。