能夠感染殺蟲的真菌種類達(dá)數(shù)千種，廣布于世界各地,，在昆蟲種群生態(tài)調(diào)控中發(fā)揮著重要的作用，代表性的金龜子綠僵菌（Metarhizium anisopliae）和蝗綠僵菌(M. acridum)等已經(jīng)被發(fā)展成為環(huán)境友好的真菌殺蟲劑,，取得了良好的生態(tài),、經(jīng)濟(jì)及社會效益。
1月6日《PLoS遺傳學(xué)》(PLoS Genetics)在線發(fā)表了中國科學(xué)院上海生命科學(xué)研究院植物生理生態(tài)研究所王成樹課題組關(guān)于這兩種殺蟲真菌比較基因組的研究論文,。該文章第一次測序,、分析了寄主廣譜的金龜子綠僵菌與蝗蟲專化的蝗綠僵菌的基因組組成與結(jié)構(gòu)的差異,，推測綠僵菌由植物病原真菌進(jìn)化而來,。同植物病原真菌及其他絲狀真菌相比，昆蟲病原真菌基因組中的蛋白酶、幾丁質(zhì)酶及脂酶等用于昆蟲體壁降解的基因家族存在顯著的擴(kuò)張現(xiàn)象,。相比于蝗綠僵菌,，除蛋白激酶外，廣譜性的金龜子綠僵菌基因組編碼有更多的不同蛋白基因,，尤其是后者的基因組中含有大量的轉(zhuǎn)座子基因以及丟失了重復(fù)引起點(diǎn)突變 (repeat-induced point mutation)的基因組防御功能,，從而促進(jìn)基因組進(jìn)化而適應(yīng)感染不同種類的昆蟲宿主。
RNA-seq高通量轉(zhuǎn)錄組分析表明,，金龜子綠僵菌與蝗綠僵菌在不同寄主體壁信號誘導(dǎo)下,，表達(dá)不同信號識別蛋白，誘導(dǎo)下游的MAPK和PKA的信號強(qiáng)度不同,，從而精確調(diào)控細(xì)胞分化,，決定了綠僵菌的寄主范圍。
綠僵菌基因組的測序為進(jìn)一步推動真菌殺蟲毒力基因鑒定,、昆蟲—真菌分子相互作用及遺傳改造并提高真菌殺蟲劑的應(yīng)用效率等基礎(chǔ)及應(yīng)用研究提供了良好的平臺,，同時也有利于促進(jìn)真菌進(jìn)化與生態(tài)學(xué)的研究。
此項研究成果得到了科技部,、國家自然科學(xué)基金及中科院項目的資助,。（生物谷Bioon.com）
生物谷推薦原文出處：
PLoS Genet 7(1): e1001264. doi:10.1371/journal.pgen.1001264
Genome Sequencing and Comparative Transcriptomics of the Model Entomopathogenic Fungi Metarhizium anisopliae and M. acridum
Qiang Gao1#, Kai Jin2#, Sheng-Hua Ying3#, Yongjun Zhang4#, Guohua Xiao1#, Yanfang Shang1, Zhibing Duan1, Xiao Hu1, Xue-Qin Xie3, Gang Zhou3, Guoxiong Peng2, Zhibing Luo4, Wei Huang1, Bing Wang1, Weiguo Fang5, Sibao Wang5, Yi Zhong6, Li-Jun Ma7, Raymond J. St. Leger5, Guo-Ping Zhao6, Yan Pei4, Ming-Guang Feng3*, Yuxian Xia2*, Chengshu Wang1*
1 Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China, 2 College of Bioengineering, Chongqing University, Chongqing, China, 3 College of Life Sciences, Zhejiang University, Hangzhou, China, 4 Biotechnology Research Center, Southwest University, Chongqing, China, 5 Department of Entomology, University of Maryland, College Park, Maryland, United States of America, 6 Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China, 7 The Broad Institute, Cambridge, Massachusetts, United States of America
Abstract
Metarhizium spp. are being used as environmentally friendly alternatives to chemical insecticides, as model systems for studying insect-fungus interactions, and as a resource of genes for biotechnology. We present a comparative analysis of the genome sequences of the broad-spectrum insect pathogen Metarhizium anisopliae and the acridid-specific M. acridum. Whole-genome analyses indicate that the genome structures of these two species are highly syntenic and suggest that the genus Metarhizium evolved from plant endophytes or pathogens. Both M. anisopliae and M. acridum have a strikingly larger proportion of genes encoding secreted proteins than other fungi, while ~30% of these have no functionally characterized homologs, suggesting hitherto unsuspected interactions between fungal pathogens and insects. The analysis of transposase genes provided evidence of repeat-induced point mutations occurring in M. acridum but not in M. anisopliae. With the help of pathogen-host interaction gene database, ~16% of Metarhizium genes were identified that are similar to experimentally verified genes involved in pathogenicity in other fungi, particularly plant pathogens. However, relative to M. acridum, M. anisopliae has evolved with many expanded gene families of proteases, chitinases, cytochrome P450s, polyketide synthases, and nonribosomal peptide synthetases for cuticle-degradation, detoxification, and toxin biosynthesis that may facilitate its ability to adapt to heterogenous environments. Transcriptional analysis of both fungi during early infection processes provided further insights into the genes and pathways involved in infectivity and specificity. Of particular note, M. acridum transcribed distinct G-protein coupled receptors on cuticles from locusts (the natural hosts) and cockroaches, whereas M. anisopliae transcribed the same receptor on both hosts. This study will facilitate the identification of virulence genes and the development of improved biocontrol strains with customized properties.
