Identification Of The Anthracnose Of Camellia Oleifera Pathogen In Different Climate Zones And Gene Differential Expression Study

Camellia oleifera Abel.is a unique woody edible oil tree species in China,which is widely distributed in tropical monsoon climate,subtropical monsoon climate and temperate monsoon climate.Camellia anthracnose is the main disease of C.oleifera,which causes reduced production of camellia oil,or plant death.Consequently,it has caused enormous economic losses to growers and consumers.In this study,polygenic（ITS-GAPDH-CHS-1）phylogenetic identification and classification of C.oleifera anthracnose fungi were carried out by combining morphological and phylogenetic methods.These pathogens come from Chengmai county of Hainan Province（tropical monsoon climate）,Zengcheng city of Guangdong Province（subtropical monsoon climate）,Changsha city of Hunan Province（subtropical monsoon climate）,Xinyang city of Henan Province（temperate monsoon climate）,Guangnan county of Yunnan Province（subtropical monsoon climate）of China.The analysis of genetic diversity,biological characteristics and gene differential expression of the main pathogenic bacteria in different climatic regions were studied by Koch postulates verification,RNA-seq and other test methods or technical means.The main results are as follows:1.From April to October,2018,213 samples of anthrax were collected from various climatic regions.And 84 pure strains were isolated,Colletotrichum fructicola was the most abundant among them,totaling 33 strains.The C.fructicola strain was found in different climatic zones and identified as the main pathogen of C.oleifera anthracnose.2.Twenty haplotypes were derived from 33 C.fructicola anthrax samples.Among them,haplotype 4 is the dominant group,including nine pathogens（HNCM020 et al.）,and is the network radiation center.The representative strains of C.fructicola in different climatic regions were screened as follows:HNCM004,GDZC002,HNCS003,HNXY009,YNGN007.3.The differences of biological characteristics of C.fructicola representative strains in different regions are as follows:（1）Morphologically,the colony color is different,and the density of mycelium is not consistent with the length.（2）The rate of spore germination and appressorium formation were as follows:HNXY009>YNGN007>GDZC002>HNCS003>HNCM004.（3）The pathogenicity of the strains were summarized as:HNXY009>HNCS003>GDZC002>HNCM004>YNGN007.4.The differences of transcriptomics characteristics of C.fructicola representative strains in different regions are as follows:（1）Discrete value:YNGN007>HNCS003>GDZC002>HNXY009>HNCM004.（2）The number of differentially expressed genes:The result showed that there were 1908 differential genes between YNGN007 and HNCS003,of which 1091 were up-regulated and 817 were down-regulated.The HNCM004 and HNCS003 had a total of 1209 differential genes,of which 637 were up-regulated and 572 were down-regulated.The GDZC002 and HNCS003 had 790 differential genes,including 356 were up-regulated and 434 were down-regulated.The HNXY009 and HNCS003 had a total of 623 differential genes,of which 339 were up-regulated and 284 were down-regulated.（3）The expression of differential gene:YNGN007>HNCM004>GDZC002>HNCS003>HNXY009.（4）The results of KEGG pathway enrichment:There were no significant enrichment of HNCM004 and HNCS003,YNGN007 and HNCS003.And there were 2 enrichment pathways between GDZC002 and HNCS003,8 pathways enriched by HNXY009 and HNCS003,respectively.（5）Common differential genes:Peroxisome/Glycerophospholipid metabolism/Amino sugar and nucleotide sugar metabolism/Glycine,serine and threonine metabolism,the common differentially expressed genes in the four groups were PIPOX/PEX12,PLD1₂,CHS 1,PIPOX,respectively.The PIPOX and PEX12 genes are related to pathogenesis.The results showed that the C.fructicola strain was the main pathogen of C.oleifera in different climatic regions.The representative strains in different climatic zones differ in colony morphology,spore germination rate/appressorium formation rate,pathogenicity and gene expression.