Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA.
Fungal Genet Biol. 2012 Aug;49(8):663-73. doi: 10.1016/j.fgb.2012.05.009. Epub 2012 Jun 15.
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.
镰刀菌禾谷种和弯孢镰刀菌是具有非常不同生活史和生态特征的毁灭性谷类病原体。禾谷镰刀菌是同宗配合的，有性孢子是其生命周期的重要组成部分，负责引发疾病。弯孢镰刀菌是异宗配合的，只产生少量的产孢结构，这些结构不是接种体的重要来源。为了鉴定两种真菌产孢结构发育的转录程序中的对应差异，进行了比较表达分析，分析了六个发育阶段。为了配合转录分析，对弯孢镰刀菌的发育进行了详细的形态学描述，并与以前对禾谷镰刀菌的形态学分析进行了比较。两种真菌的形态发育相似，除了在弯孢镰刀菌的产囊体中观察到可能的三丝体，这在任何镰刀菌物种中都没有报道过。对两种真菌的 9000 多个同源基因进行了表达测量。在每个时间点对高度表达的同源基因进行功能分配，结果表明，大多数高度表达的基因属于“未分类蛋白”类别，这反映了两个物种的有性发育基因特征缺乏。同时检查形态发育和阶段特异性基因表达表明，有性发育过程中侧丝的退化是一种细胞凋亡过程。两种真菌中交配型基因的表达不同，这可能反映了它们在有性发育中所起的不同作用。总的来说，基因表达的差异反映了产孢结构在禾谷镰刀菌和弯孢镰刀菌生活史和生态学中的作用更大。
