Genome-wide Analysis Of Oomycetes And Screening Of Pathogenicity-related Proteins

Oomycetes are fungal-like microorganisms with similar morphological characteristics to filamentous fungi,and can cause pythium,phytophthora,downy mildew and white rust disease.But the relationship of oomycetes is related to heterokont,biflagellate,golden-brown algae.With the development of genomics theory and technology,a large number of oomycetes genome has been sequenced.But the molecular basis or evolution of obligate biotrophic and semibiotrophic pathogens is not perfect.In this study,the genomic structure,homology,and differential gene enrichment pathways of the whole genome sequence of oomycetes were systematically studied through various databases such as National Center for Biotechnology Information(NCBI),Ensembl Protists,and Kyoto Encyclopedia of Genes and Genomes(KEGG),by a genome-wide orthologus analysis.Base on this,the major pathways of enrichment of differential genes are ascorbic acid and metabolism,steroid biosynthetic fructose and mannose metabolism,tyrosine metabolism and so on.Detailed analysis of ABC(ATP-binding cassette)transporters,cyclophilin(CYP)and nudix proteins families,including: screening differential proteins of Phytophthora and downy mildew,and their phylogenetic relationship in each pathways,screening pathogenic genes of oomycetes from different proteins families,proteins structure analysis,phylogenetic relationship and transcriptome expression at different life stages.This study explores the effects of oocysts from necrotrophic,hemibiotrophic to obligate biotrophic lifestyles on the plant infection process,and screens for potential pathogenic genes,which may help find potential pathogenic diseases genes.It will have more or broader special roles in plant pathogens,and provide molecular basis for evalution and screening of plant-oomycete resistant resouces.The main results obtained are as follows:1.There have obvious differences of 9 oomycete species in genome size,genomic characteristics,orthologous and differential genes enrichment.And there have two independent origins in downy mildew,which many important genes are lost in the long evolution.Many gene families of Phytophthora have expanded,and these expanded genes are likely to be candidate effectors related to the pathogenicity of oomycetes.2.There have 15 proteins of 8 enrichment pathways absented in downy mildew.Among them,aldose-1-epimerase,gluconolactone enzymes and catechol O-methyltransferases may have undergone horizontal transfer from fungi or prokaryotic bacteria.These proteins may be involved in the detoxification of plant toxins or act directly on plants as pathogenic factors.They can use as candidate pathogenicity-related proteins.3.A total of 1 791 ABC transporters were identified from 22 oomycetes.And the evolution origin of ABC transporter family of oomycetes is abundant.The expression level of ABC transporters protein of oomyces at different life stages is specific.Meanwile,most ABC transporters mainly transport substrates to participate in the biological trophic stage and semi-biological trophic stage.Among them,ABCA Ⅲ,full-length ABCB Ⅳ,half-size ABCB Ⅱ,ABCD and ABCG can be used as candidate pathogenicity-related proteins.4.16 orthogroups of CYP proteins were identified from 22 oomycetes,and 6orthogroups cotain bigram proteins,which CYP-FBKP only present in Sarmenopiles and Alveolates.The phylogenetic relationship was affected by different CYP domains.At different stages of infection process,each CYP gene of Phytophthora infestans and Plasmopara halstedii have different expression,and the differential expression of CYP gene during the infection process is consistent with multiple functions of CYP proteins,and not only limited to pathogenicity.And oomc CYP06,oomc CYP07,oomc CYP09,oomc CYP12 and oomc CYP14 can be used as candidate pathogenicity-related proteins.5.16 orthogroups of nudix proteins were identified from 22 oomycetes,and 10 orthogroups contains bigram proteins.The nudix proteins of most oomycetes were ralated to fungi,and have formed multiple paralogs in evolution with different function.The nudix genes expression profies of Phytophthora sojae and Plasmopara halstedii prove the protential role of nudix proteins during infection.And oomc NUD00,oomc NUD01,oomc NUD05,oomc NUD07 and oomc NUD09 can be used as candidate pathogenicity-related proteins.In summary,we screened 18 groups’ candidate pathogenicity-related proteins from oomycetes genomes,which can be used as candidate gene libraries for later functional verification.