真菌有性生殖调控与进化

Sexuality Control and Sex Evolution in Fungi

以真菌为对象的有性生殖机制研究揭示了普遍存在于真核生物中的生物学现象及规律,包括染色体倍性变化、减数分裂形成配子、交配对象识别及细胞-细胞融合形成合子等.真菌的有性生殖由交配型位点控制,除了类似其他真核生物两性生殖的异宗配合外,还包括同宗配合和次级同宗配合,部分物种的单倍体还具有交配型互换的能力.互补交配型的单倍体通过荷尔蒙及其受体进行相互识别,再经过G蛋白偶联受体介导的信号途径调控有性生殖过程及子实体发育,这一过程受多种胞内调控因子及外界环境条件的影响.不同真菌类群生殖方式的演化与物种进化仍缺少统一的规律.进一步研究揭示,真菌有性生殖的调控机制及环境诱导因子,不仅具有重要的理论意义,也有利于促进不同经济真菌子实体的人工培养及高效利用.

Fungi have been used as robust and genetic models to study the mechanisms of eukaryotic sexuality controls, which have revealed the common mechanisms including ploidy changes, the formation of gametes via meiosis, recognition of mating partner and cell-cell fusion to form zygotes. Sexuality in fungi is controlled by mating-type loci. There are three modes of sexual reproduction in fungi, heterothallism （very much like two sex mating system in other eukaryotes）, homothallism and pseudohomothallism. Different from other eukaryotic organisms, some fungal species like yeasts can perform mating-type switching. Fungal haploids with opposite mating-type locus can recognize each other by a compatible pheromone-receptor system. The sexual process and fruiting-body development are regulated by the following G-protein coupled receptor pathways. The initiation of fungal sex is also determined by multiple intracellular as well as extracellular factors. The disparity has been frequently observed in different fungal lineages in terms of the association between fungal sexual mode evolution and speciation. Future studies to unveil the environmental cues in initiating fungal sexuality will not only facilitate the understanding of myriad forms of fungal sex but also benefit the effective use of economic fungi by artificial cultivation of fungal fruiting-bodies.