Phylogeny And Comparative Genomics Of Metarhizium And Related Genera

Metarhizium,as a group with rich morphological and ecological diversity in Clavicipitaceae,is very rich in species diversity and has a wide distribution and diverse hosts.The species in Metarhizium with simple morphology in asexual-stage have so tiny distinction that it’s difficult to distinguish.Up to now,the genus Nigelia,Keithomyces,Marquandomyces,Papiliomyces,Purpureomyces,Sungia and Yosiokobayasia have been respectively independent of Metarhizium.With the increasing species,the boundary between Metarhizium and related genera are indistinct,and the genetic relationships among species are unclear.The maximum range of sampling was conducted among genus Metarhizium and its related genera in Clavicipitaceae in the present study.We reconstructed phylogenetic framework of the family Clavicipitaceae using combined ITS and 5-gene(nr SSU,nr LSU,tef,rpb1 and rpb2)dataset in order to solve the problem that Mertarhizium,Pochonia,Metapochonia and other related genera have low support rate.Combining morphological and ecological characteristics,species from Metarhizium and its related genera and their positions were defined and determined,respectively.Besides,some species classified into wrong systematic positions and pending species were revised based on 5’tef gene sequence analysis.Combined with the second generation and third generation sequencing technology,high quality draft genome sequences of five species from Mertarhizium and its related genera were acquired.In order to establish more reliable phylogenetic tree to solve the phylogenetic problem of Mertarhizium and its related genera on genome level,the phylogenetic framework of Clavicipitaceae,Ophiocordycipitaceae and Cordycipitaceae was constructed through the comparative genomics approach.In order to reveal adaptive evolution direction of Mertarhizium species and its closely related species on genome level,M.robertsii with a wide host range was added into comparation because the host range of five species is very limited.The main results were as follows.(1)The most extensive taxon sampling was conducted among genus Metarhizium and its related genera.In ML and BI phylogenetic analyses,ITS and 5-gene sequences of 182 taxa were employed to reconstruct phylogenetic framework of the family Clavicipitaceae.The support of the clades separating Metarhizium,Pochonia,Metapochonia and other related genera did improve.(2)Based on phylogenetic analysis and the characteristics of morphology and ecology,the taxonomical statuses of 478 specimens from 35 species collected in this study were determined,of which there were 17 new species and 2 new combinations.Keys to species in Mertarhizium were constructed,and 10 new species and 1 new combination in this genus were described.The new species consist of M.aranearum H.Yu,Y.Wang,Zhu L.Yang et al.,M.giganteum H.Yu,Y.Wang,Zhu L.Yang et al.,M.hepialidicola H.Yu,Y.Wang,Zhu L.Yang et al.,M.laosense H.Yu,Y.Wang,Zhu L.Yang et al.,M.neoanisopliae H.Yu,Y.Wang,Zhu L.Yang et al.,M.porcellioum H.Yu,Y.Wang,Zhu L.Yang et al.,M.pumatense H.Yu,Y.Wang,Zhu L.Yang et al.,M.thailandicum H.Yu,Y.Wang,Zhu L.Yang et al.,M.tipulidicola H.Yu,Y.Wang,Zhu L.Yang et al.,M.yunnanense H.Yu,Y.Wang,Zhu L.Yang et al.and new combination consist of M.jiangxiense(Z.Q.Liang,A.Y.Liu & Yong C.Jiang)H.Yu,Y.Wang,Zhu L.Yang et al.(3)Based on morphological characteristics observation and phylogenetic analysis,a new genus Napialiocordyceps was established,and the 7 new species and 1 new combination were described,i.e.,N.aeruginosa H.Yu,Y.Wang,Zhu L.Yang et al.,N.furcata H.Yu,Y.Wang,Zhu L.Yang et al.,N.inflata H.Yu,Y.Wang,Zhu L.Yang et al.,K.jiangxiensis H.Yu,Y.Wang,Zhu L.Yang et al.,K.sinensis H.Yu,Y.Wang,Zhu L.Yang et al.,K.terrestris H.Yu,Y.Wang,Zhu L.Yang et al.,Pur.lepidopterorus H.Yu,Y.Wang,Zhu L.Yang et al.,N.shibinensis(T.C.Wen,J.C.Kang & K.D.Hyde)H.Yu,Y.Wang,Zhu L.Yang et al.(4)The evolution direction of Mertarhizium and its related genera in terms of morphology was discussed in this study: the asexual sporulation structure evolved from Lecanicillium-like to Paecilomyces-like;conidia evolved from globose and globose-like(ellipsoidal,ovoid,fusiform,pyriform,etc)to cylindrical;spinulose conidia came from smooth conidia.The present study revealed a directional speciation continuum for Mertarhizium species from specialists with narrow host ranges to transitional species and then to generalists that paralleled insect evolution.Correspondingly,the reproduction mode of these species in nature has evolved from sexual reproduction to asexual reproduction.(5)Phylogenetical reconstruction of Clavicipitaceae,Ophiocordycipitaceae and Cordycipitaceae was carried out based on the whole genome data.Using comparative genomics methods,phylogenetical tree of six species in four genera Metarhizium,Purpureomyces,Keithomyces and Napialiocordyceps was constructed.Their topological structures coincided with our phylogenetical framework of Clavicipitaceae based on six genes,which fully demonstrated that the phylogenetical framework constructed by multiple genes can also reflect or partly reflect the true evolutionary relationship between species and obtain correct of estimate of the species tree.The comparative genome analysis based on six species indicated that:(1)the genome size can not reflect its ability to encode proteins;(2)the adaptation of entomopathogenic fungi to the host range is related to the size and function of protein family.