Resource Collection, Identification And Biocontrol Evaluation Of Trichoderma Isolated From Southern China

As the application of Trichoderma spp. in biocontrol field of plantdiseases, Trichoderma has generallly been playing a more and moresignificant role in agricultural production. At first in our research, weintend to detect distribution and diversity of Trichoderma isolated fromdifferent types of soil in southern China and to find out how dominantTrichoderma species were distributed in different eco-regions in southernChina. Furthmore, we establish collection of Trichoderma resources andcomprehensive evaluation system towards bioncontrol function ofTrichoderma strains, and eventually we screened some efficient antifungalTrichoderma strains against soilborne disease of cucumber and maizethrough multiple methods, etc. The main results were as follows:In more than two years,886Trichoderma strains were isolated from215soil samples. Utilizing comprehensive approaches of phylogeneticanalysis by detecting molecular markers (i.e. ITS-rRNA, Tef1-α) andmorphological microscopic observation, these strains belonging to21taxawere eventually classified into species as follows: T.asperellum,T.atrioviride, T.aureovriride, T.brevicompactum, T.citrioviride,T.erinaceum, T.gamsii, T.hamatum, T.harzianum/Hypocrea1ixii,T.intricatum, T.koningii/Hypocrea koningii, T.koningiopsis,T.longibranchiatum, T.pleuroticola, T.reeseii/Hypocrea jecorina, T.spirale,T.stromaticum, T.tomentosum, T.velutinum, T.virens/Hypocrea virens,T.viride. Of these species, T.intricatum/Hypocrea intricata andT.stromaticum/Hypocrea stromatica were identified as new Chinese recordspecies. Moreover, in terms of geographic distribution of Trichoderma species, T.harzianum was the most abundant species (23.2%) distributedwidely in south of China, and followed by T.asperellum (22.5%) andT.hamatum (18.1%). Afterwards, we analyzed diversity distribution of thespecies according to their geographic origin, and conducted phylogeneticanalyses about the point of genetic evolution. Finally, a Trichodermaresources preservation center was established, i.e. Center for culturecollection of Trichoderma, Shanghai Jiao Tong University, with more thantwo thousands strains preserved. More importantly, an auto-retrievalsystem for species identification was invented on the basis ofmorphological traits among species.Furthermore, to screen high efficient biocontrol Trichoderma strainsfrom resource library, we observed the changes of characteristics ofsporulation and mycelium, and analyzed antagonistic activity againstpathogen, pathogen survival ratio rement after antagonistic microbetreatment as well as plant disease control pot test. In the study, sixbiocontrol Trichoderma strains with high activity against Fusariumoxysporum f sp. cucumerinum and Fusarium graminearum Schw. weresuccessfully screened based on results from classification of sporulationtype, dual test, spore survival measurement and pot experiment. Forinstance, root irrigation with conidiospores suspension of T.asperellumGDFS1009was able to achieve86.34%control of cucumber wilt causedby Fusarium oxysporum f sp. cucumerinum in pot experiment; similarly,application of conidiospores suspension of T.asperellum GDZQ1008totreat maize root would result in70.67%control of maize seedling stalk rotcaused by F.graminearum. In addition, we also found Trichoderma strainscould stimulate the growth of cucumber and maize seedlings, and improveboth crop vigor showing more thriving root development and morechlororphyl synthesis in leaves.The efficient screening technique of Trichoderma as biocontrolmicrobe was established through principal component analysis based onthe correlation significance of chitinase, β-1,3-glucanase, extracellular protease, peptaibols and polyketids with biocontrol efficiency. All thosebiocontrol factors were crucial for Trichoderma biocontrol ability.Particularly, the former three factors were considered to be more importantfor comprehensive evaluation of Trichoderma as biocontrol agent.