A molecular approach to analyze factors affecting the mode of conidiogenesis and its diversity.

在目前包括蘑菇和担子菌酵母在内的真菌分类中，已采用分生孢子发生模式作为高等分类群的分类标准，然而，最近大量的系统发育研究表明，其中一些并不能反映系统发育。球孢子虫就是其中的一种，它是从母细胞的雄蕊顶端产生的，成熟后排出。当研究盾叶薯蓣属(主要是大黄花属及其近缘种)同一种的种间和菌株间的分生孢子形成活性时，即使在同一物种中，也不一定反映出菌株之间的系统发育及其强度差异，表明分生孢子的形成不是一个稳定的特征。因此，这一特性不适合作为高等分类群的分类标准，在真菌系统学重建时也不宜使用。以稻瘟霉JCM 5281为材料，对形成气球分生孢子的条件(保存在实验室工作台上的培养基)和未形成气球分生孢子的条件(保存在盖紧的塑料容器中的培养基)进行了抑制消减杂交，并观察到线粒体基因的差异。荧光显微镜下的形态观察表明，具雄蕊和气球分生孢子的母细胞比营养细胞表现出更强的荧光强度。在这些母细胞和气球分生孢子中，线粒体似乎存在于细胞表面附近，有时像颗粒一样粘连在一起。根据这些观察结果，推测分生孢子的形成与线粒体的数量变化及其形态变化有关。

The mode of conidiogenesis has been employed for a taxonomic criterion of higher taxa in the present taxonomy of fungi including mushrooms and basidiomycetous yeasts, however, recent numerous phylogenetic studies showed that some of these do not reflect the phylogeny. Ballistoconidium, which is made on the tip of the sterigma from the mother cell and discharged when it matures, is a one of these. When the ballistoconidium-forming activity was studied between species and among strains belonging to the same species in the genus Dioszegia, mainly D. crocea and related species, it does not necessarily reflect the phylogeny and its strength varied among strains even in the same species, indicating that formation of ballistoconidium is not a stable characteristic. Therefore, this characteristic is not appropriate as a taxonomic criterion of higher taxa, and should not be used when the reconstruction of the systematics of fungi is made.Suppression subtraction hybridization between the ballistoconidium-forming condition (media kept on a workbench in the laboratory) and the condition under which ballistoconidium not formed (media kept in a plastic container covered tightly with a lid) was performed using Bullera oryzae JCM 5281, and the difference was observed in mitochondrial gene. The morphological observation by a fluorescence microscopy showed that the mother cells with sterigma and ballistoconidia demonstrated stronger intensity than those of vegetative cells. In such mother cells and ballistoconidia, mitochondria seemed to exist near the surface of cells and occasionally cohere like particles. Based on these observations, the formation of ballistoconidium is assumed to be related to the quantitative change of mitochondria accompanied with their morphological changes.