| Malus sieversii belongs to the Tertiary relict species and is a treasure trove of apple genetic resources.It is listed as a Chinese endangered secondary protected plant,but it is seriously threatened by disease.Trichoderma is recognized as an efficient and safe biocontrol factor in the world.Therefore,the use of Trichoderma to control M sieversii disease in Xinjiang region is promising.In this study,47 soil samples were collected from the root soil of the wild fruit forest in Gongliu County,Xinjiang Region,and the classification and identification of Trichoderma were carried out.Two strains of biocontrol dominant strains were screened and studied.The main results are as follows:Eight Trichoderma species were identified,including.harzianum,T.rossicum,T.asperellum,T.longibrachiatum,T.hamatum,T atroviride,T.piluliferum and.viridescens.A total of 364 strains of T rossicum,276 strains of T.viridescens,85 strains of T.asperellum,63 strains of T.harzianum,40 strains of T.atroviride,9 strains of T.piluliferum,6 strains of T.hamatum,andl strain of T.longibrachiatum were isolated.A total 844 strains of Trichoderma.are preserved in Laboratory microbiological Culture Collection,numbered NECC20362-NECC21205.The colony morphology and microstructure(conidia and conidiophores)of 8 Trichoderma species on PDA,CMA,SNA and MA media were described.The characteristics of eight species of Trichoderma were observed using a scanning electron microscope.Under different scanning electron microscopes,different Trichoderma spores were observed.The exine ornamentation on the surface of Trichoderma spores was used as the basis for morphological identification,and it may also affect the life history of Trichoderma,such as spore identification and germination.The dominant biological control Trichoderma in Gongliu County of Xinjiang was screened as.harzianum and T.rossicum.Using T.harzianum T2 and.rossicum T7 contrast test with Fusarium oxysporum and Alternaria alternata,two species of Trichoderma were found to be effective in inhibiting the growth of two pathogens.The antibacterial rate was calculated to find T.harzianum T2 against F.oxysporum.The inhibition rate was 75.47%,and the inhibition rate against A.alternata was 78.17%.The bacteriostasis rate of T.rossicum T7 against T.oxysporum was 79.66%,and the bacteriostatic rate against A.alternata was 91.53%.After treating M.sieversii seedlings in different ways,it can be found that the Trichoderma can effectively reduce the damage of the pathogenic fungal by observing the living leaves of the plants,while M.sieversii seedlings treated only with Trichoderma grow better.NBT staining of M sieversii leaves showed that the pathogenic fungal increased the active oxygen content in the leaves of plants,while the treatment of plants with Trichoderma and pathogens reduced the active oxygen content of the leaves and protected them.By observing the roots of the plants,T。harzianum T2 and.rossicum T7 all contributed to the growth of the main roots and lateral roots of.sieversii seedlings.F.oxysporum has serious damage to the roots of M sieversii seedlings,while A.alternata has little effect on the roots.The use of both Trichoderma can effectively alleviate the effects of F.oxysporum and A.alternata on the roots of M sieversii seedlings.Under the scanning electron microscope,T.harzianum T2 and T rossicum T7 that have been treated for 5 days were observed to produce dense hyphae on the root surface of M sieversii seedlings.At the same time,the spore germination of T.harzianum was observed,indicating that the control of Trichoderma was acceptable.continuous.In addition,the morphology of the exine ornamentation on the surface of the T.rossicum spores was observed to change and fuse with the hyphae.The expression levels of PR1-1,PR1-2,PDF-1 and PDF-3 genes after treatment of M.sieversii seedlings with Trichoderma and A.alternata were analyzed by gene RT-qPCR analysis.The results showed that all four genes could respond to pathogen infection.In the presence of pathogens and Trichoderma,their expression levels were higher than those of pathogens alone,and peaked after 72 hours of treatment,35.59 times,29.79 times,18.55 times and 12.35times respectively,indicating that Trichoderma can enhance the response of M.sieversii to pathogens.The response of M sieversii to pathogens.However,the effect of Trichoderma treatment on the expression of PR1-1 and PR1-2 was not obvious,they reached 2.36 times and 1.55 times respectively,but it significantly increased the expressions of PDF-1 and PDF-3,at 72 h and 72h,they reached 6.56 times and 14.85 times respectively,indicating that Trichoderma may not induce salicylic acid signaling pathway related genes.The expression is mainly through the jasmonic acid pathway to improve the disease resistance of M.sieversii.The local biocontrol dominant Trichoderma strains in Gongliu County were screened out and provided guidance for the biological control of M sieversii. |
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