Study On The Characteristics Relating To Pesticides Of Three Marine Trichoderma Spp

Trichoderma spp.had attracted great interest as probiotics because of abundant enzymes,multiple effects and environmental friendliness,especially in the field of plant diseases biocontrol.At present,there were less reports on Trichoderma spp.in marine habitats compared with terrestrial habitats,and the abilities of Trichoderma spp.were observably affected by habitats.Therefore trichoderma strains were isolated from marine habitats,and then systematic studies of selected strains were carried out in this paper,including identification,mutagenesis,antifungi activity,plant growth-promotion and related genes.The results are as follows:1.A total of 109 Trichoderma strains were isolated from marine animals,plants and sediments with PDA,RBA,MPDA and modified TSB media,and three of which respectively named M3-2,Y5-1 and X20-1 were selected according to the inhibition abilities against Alternaria solani,Botrytis cinerea and Fusarium graminearum.Through the morphological characteristics and the constructions of phylogenetic tree,M3-2,Y5-1 and X20-1 were identified as Trichoderma reesei,Trichoderma koningiopsis and Trichoderma erinaceum,respectively.2.After the complex mutagenesis of microwave and ultraviolet rays,3 mutant strains named M3-2xy1,Y5-1xy2 and X20-1xy3 were obtained,with higher antifungal activities and the spore germinations of 3.45×108,3.10×108 and 2.55×108 cfu/cm2,which increased by 88.52%,63.16% and 180.22%,respectively,compared to original strains.Moreover,these mutants formed chlamydospore,and XG20-1 had the highest chlamydospore germination of 3.56×108 cfu/m L.3.All of the 3 mutant strains M3-2xy1,Y5-1xy2 and X20-1xy3 had strong inhibition effects on six pathogenic fungi,Alternaria solani,Botrytis cinerea,Pyricularia oryzae,Sclerotina sclerotiorum,Phytophthora infestans and Fusarium graminearum.Among them the inhibition rates against S.sclerotiorum were the highest,which were up to 92.6%,90.7% and 82.6%,respectively.In addition,the superparasitism to Alternaria solani was observed in this paper.PCR analyses showed that the 3 strains had antifungal related genes Tex1 and Nag1.4.All three strains had the abilities of releasing phosphorus and potassium,degrading cellulose,secreting siderophore,and producing phytase and indole-3-acetic acid(IAA).The productions of IAA in three strains were 2.61,1.57 and 1.92 mg/L,while the relative contents siderophore were 89.4%,87.8% and 86.4%,respectively.5.The results of potted experiment showed that the three Trichoderma spp.had obviously growth-promoting effects on cucumber and cabbage.After treatment,the seed germination,seedling height,root length,fresh weight,content of chlorophyll,reducing sugar and soluble protein had been improved in different degree.Meanwhile,significant effects of these strains on control of cucumber gray mold,powdery mildew and anthracnose disease were observed.Among them,M3-2xy1 had the highest control effect of 87.7% on powdery mildew,while Y5-1xy2 had the highest control effect on cucumber gray mold and anthracnose,up to 65.8%,75.5%,respectively.