Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, 200032, China.
Appl Microbiol Biotechnol. 2013 Apr;97(7):2797-804. doi: 10.1007/s00253-013-4771-7. Epub 2013 Feb 23.
Ascomycete Cordyceps sensu lato consists of hundreds of species of fungi capable of infecting different insects. Species of these fungi are either valued traditional Chinese medicines or used for biocontrol of insect pests. Phylogenomic analysis indicated that fungal entomopathogenicity has evolved for multiple times, and the species of Cordyceps were diverged from the mycoparasite or plant endophyte. Relative to plant pathogens and saprophytes, Cordyceps species demonstrate characteristic genome expansions of proteases and chitinases that are used by the fungi to target insect cuticles. Only a single mating-type gene identified in the sequenced species of Cordyceps sensu lato indicates that these fungi are sexually heterothallic, but the gene structure of the mating-type loci and frequency in performing sexual cycle are considerably different between different species. Similar to the model fungus Neurospora crassa, Cordyceps and related fungi contain the full components for RNA interference pathways. However, the mechanism of repeat-induced point mutation varies between different fungi. Epigenetic rather than genetic alterations are majorly responsible for the frequent occurrence of culture degeneration in Cordyceps-related species. Future genetic and epigenetic studies of fungal sexuality controls and culture degeneration mechanisms will benefit the cost-effective applications of Cordyceps and related fungi in pharmaceuticals and agriculture.
广义虫草属的子囊菌包含了上百种能够感染不同昆虫的真菌。这些真菌的一些种被用作传统中药，一些种则被用于害虫的生物防治。系统基因组分析表明，真菌的昆虫病原性已经进化了多次，而虫草属的种则是从真菌寄生物或植物内生菌分化而来的。与植物病原菌和腐生菌相比，虫草属的种展示出了蛋白酶和几丁质酶的特征性基因组扩张，这些酶被真菌用于靶向昆虫的外骨骼。在已测序的广义虫草属的种中仅发现了一个交配型基因，这表明这些真菌是有性异宗配合的，但交配型基因座的基因结构和进行有性循环的频率在不同种之间有很大的差异。类似于模式真菌粗糙脉孢菌，虫草属和相关真菌包含了 RNA 干扰途径的完整成分。然而，重复诱导点突变的机制在不同真菌之间存在差异。在虫草属相关种中，频繁发生的培养退化主要是由表观遗传而非遗传改变引起的。对真菌有性生殖控制和培养退化机制的未来遗传和表观遗传研究将有助于虫草属和相关真菌在医药和农业中的成本效益应用。
