| Trichoderma is a genus of fungi largely and widely distributed around the world.It has the important economic value and application prospects in the field of industry,agriculture and environmental protection.As an important biocontrol agent,Trichoderma is important in the prevention and control of plant diseases.In this paper,624 soil samples were collected from the agricultural ecosystems of 21 regions in Yunnan,Guizhou,Shaanxi,Sichuan provinces and Chongqing municipality,and 25996 fungal colonies were produced on the PDAm plates by using soil dilution plating method,from which 1118 Trichoderma strains were isolated.Trichoderma was dominant genus in the agricultural soil since its dominance value was 0.043(>0.02).Through the combination of DNA barcoding(ITS and TEF)and morphological observation,we identified 20 species of Trichoderma as followed:T.asperellum(458 isolates),T.harzianum(215 isolates),T.atroviride(143 isolates),T.hamatum(145 isolates),T.koningiopsis(47 isolates),T.brevicompactum(33 isolates),T.virens(27 isolates),T.tomentosum(13 isolates),T.longibrachiatum(8 isolates),T.erinaceum(7 isolates),T.gamsii(4 isolates),T.fertile(3 isolates),T.spirale(3 isolates),T.orientale(2 isolates),T.pleuroticola(2 isolates),T.viride(2 isolates),T.caerulescens(2 isolates),T.pleuroti(1 isolates),T.reesei(1 isolates),T.velutinum(1 isolates).Among these,T.asperellum,T.hamatum,T.atroviride and T.harzianum were the dominant species for their dominance(Y)values of 0.410,0.130,0.128 and 0.192.52 haplotypes from these species were obtained based on ITS sequences using DnaSP software.Among identified 20 species,T.harzianum had the most abundant haplotypes(10),followed by T.asperellum(7)and T.atroviride(7),which indicated that genetic diversity of these species was abundant.Through the Maximum Parsimony and Bayesian inference approaches the ITS sequences of 52 haplotypes were selected to gain the phylogenetic tree,which conformed to the major published ones.In addition,the geographical distribution and dominance of Trichoderma spp.in the 5 provinces(municipalities)were discussed.The Trichoderma species,quantity and dominant species vary in different provinces.Yunnan province comprised 13 species,in which T.asperellum,T.hamatum and T.harzianum were dominant.T.asperellum,T.hamatum,and T.harzianum were the dominant species among 9 species found in Guizhou.Also,14 species were identified in Sichuan and Chongqing,along with T.hamatum,T.asperellum,T.koningiopsis and T.atroviride as the dominant species.In Shaanxi province there were 12 species with T.asperellum,T.hamatum,T.koningiopsis and T.atroviride considered to be the dominant species.The dominant species distribution also showed different.T.asperellum and T.hamatum were more common in the southern region,but few in the north.T.atroviride were found only two in Guizhou Province while T.harzianum appeared in majority of these sites.Collection of Trichoderma species in different crop soils suggested significant differences.More species were isolated in the rice and maize soils rather than the wheat soil.Besides,to explore the antagonistic activity,the dual culture assays against three common phytopathogenic fungi(Fusarium oxysporum,Botrytis cinerea and Rhizoctonia solani)were carried out.The result revealed that these species showed diverse in antagonistic capability against phytopathogenic fungi and different isolates of the same species also were not same in antagonistic activities to these phytopathogenic fungi.Considering the Trichoderma’s ability of antagonism and mycoparasitism,1118 strains of Trichoderma were screened into 120 strains with the best biocontrol potential.The enzyme activity of cell wall-degrading enzymes in these biocontrol strains,such as chitinases,β-1,3-glucanase and proteases,were gained.Among these biocontrol strains,the most of them belong to dominant species. |
PDF Full Text Request