The Response Of Defense Enzymes In Populus Davidiana×P.Alba Var.Pyramidlis To Trichoderma Asperellum And Alternaria Alternate

In order to elucidate the defense mechanism of Trichoderma on poplar leaf blight,the interaction system among Populus davidiana×P.alba var.pyramidlis(Shanxin poplar),Alternaria alternata and Trichoderma asperellum and A.alternata-T.asperellum were established.The expression patterns of differential expression genes of POD,SOD,CAT,APX,GR and PPO in stems tip,leaves and roots of Shanxin poplar under different induction conditions were comparid by transcriptome sequencing which verified by qRT-PCR.Besides,the activities of defense enzymes and the changes of key difrerential expressed genes of POD and SOD at different time were detected.The main research results were listed as follows:1.The activities of defense enzymes in the stem tips,leaves and roots of Shanxin poplar were improved on the second day with rhizosphere colonization of.asperellum,which increased the resistance of Shanxin poplar against to A.alternata in a way on the sixtieth day.It was speculated that T.asperellum would enhance the disease resistance of Shanxin poplar by inducing changes of defense enzymes activities.2.489 genes related to ROS signaling pathway were screened from the transcriptome database of Shanxin poplar interacted with two fungus for 48 hours,including 39 genes from stem tip,121 genes from leaves and 138 genes from roots.Among them,the co-induction of T asperellum-A.alternata with Shanxin poplar had the most effect on the genes expression pattern related to defense enzyme.The expression of PdpapPODs and PdpapCATs in leaves,PdpapSODs in roots were influenced maiuly by A.alternata,while T.asperellum had a large influence on the expression of PapapGRs in stem tip,PdpapSODs and PdpapPPOs in leaves and PdpapGRs in roots.Besides,the co-induction of T.asperellum-A.alternata effected primarily the expression of other genes.3.There were 92 differentially expressed genes that encodes defense enzymes were screened by gene expression in different treatment groups of transcriptome database.Bioinformatics analysis showed that:most of these genes had manifested hydrophilia which may be soluble proteins except CAT.The subcellular localization prediction of proteins showed that PdpapPODs were located mostly in the secretory pathway,PdpapSODs was located mostly in mitochondrial targeted peptides,while PdpapCATs,PdpapGRs and PdpapPPOs were mostly located in chloroplast transporter peptides.These genes were located in different organelles,which implied that antioxidant function and the dynamic balance of free radicals in plants were achieved by the interaction of different organelles related to clear ROS through multiple mechanisms.Besides,there was an evolutionary affinity of the encode genes of enzyme among Shanxin poplar,P.tomentosa,Arabidopsis thaliana and Oryza sativa,and some of them were grouped together with strong support(100%),which meaned some functional similarities.4.The co-induction of T asperellum-A.alternata had a significant effect on the expression of PdpapPOD and PdpapSOD on the second day,and the expression of PdpapPOD and PdpapSOD were upregulated inducing by.asperellum on the sixtieth day.It was suggested that the expression of PdpapPOD and PdpapSOD were induced by T asperellum after a period of time.