| Trichoderma is abundant and widely distributed all over the world.As biocontrol fungus,Trichoderma has important economic value and application prospects in plant disease control.Based on ITS(internal transcribed spacer of ribosomal DNA)sequence analysis,tef1(translation elongation factor 1 alpha)and rpb2(the second-largest subunit of DNA-directed RNA polymerase Ⅱ)were used in this study.The phylogenetic trees of Trichoderma and its seven main branches were established by maximum likelihood method(ML)and maximum parsimony method(MP).3281 Trichoderma isolates were identified as 20 known species,including T.asperelliodes、T.asperellnm T,atroviride、T.capillare、T.confertum、T.croceum、T.erinaceut、T.gamsii、T.guizhouense、T.hamatum、T.harziannum,、T.longibrachiatum、T.longifaliclicum、T.orienntale、T.paratroivide、T.pleuroTicolc、T.protrudenst、T..subviride、T.virens.T.viride:at the same time,301 isolates of Trichoderma were identified as 22 suspected new species of Trichoderma.The results also showed that T.asperellum,T.atroiviride、T.virens、T.hamatum、T.harzianian and T.asperellum were the dominant Trichoderma species in the farmland ecosystem of China,and their dominance degrees were 0.063、0.116、0.198、0.224、0.235.183 isolates of Trichoderma antagonistic strains have been screened in our laboratory,and their activities of degrading enzymes for hemicellulose.、lignin、tannin and saponin have been determined.17 isolates of Trichoderma antagonistic strains have been screened through the test of seed soaking,germination inhibition and in vivo inoculation of Trichoderma,which can inhibit pathogenic bacteria,promote seed germination and protect the development of seeds to complete seedlings.Two rounds of co-culture experiments were carried out between strains and cucumber and it was found that mixed strains could promote cucumber growth to a certain extent more than single strains.17 isolates of Trichoderma fungi were tested in pot with substrate,and it was found that functional strains could induce cucumber resistance to gray mould to a certain extent and the mixed strains showed better biocontrol effectIn summary,Trichoderma isolates in farmland ecosystem in China are rich in diversity.The dominant species of Trichoderma are T.asperelum、T.hcarziamum.T.hamatum、T.virenn.s and T,atroviride.The optimum strain of Trichoderma fungi can not only promote the seed germination and plant growth of cucumber,but also induce disease resistance of cucumber. |
