Isolation Of Antagonistic Actinomycetes And Diversity Analysis Of Soil Actinomycetes In Tobacco Rhizosphere Soils Of Luoyang

Tobacco is an important economic crop in China.Black shank caused by Phytophthora parasitica is a devastating soil-borne disease with widespread and serious damage in tobacco.At present,the control measures of the disease mainly include planting disease-resistant varieties,chemical control,biological control and agricultural control,among which biological control has a good application prospect for the sustainable development of tobacco production.Using antagonistic actinomycetes to control tobacco disease is one of the research hotspots in recent years.In order to identify the species of antagonistic actinomycetes in the root circumference soil of tobacco plants in luoyang tobacco region,and to preliminarily explore the diversity and community structure of soil actinomycetes.The antagonistic effects of actinomycetes from rhizospheric soils in Luoyang tobacco-growing areas and their fermentation broths against P.parasitica were determined by improved plate confrontation test and mycelial growth rate method.Dominant antagonistic strains were identified by morphological and biochemical features and 16 S rDNA analysis.Illumina MiSeq sequencing technology was used to preliminarily explore the diversity and community structure of soil actinomycetes.The research achievements as follows:(1)A total of 496 single colonies of actinomycetes were selected from the diluted coated plates of actinomycetes isolated from the root circumference soil of tobacco plants,and further separated and purified to obtain 227 single colonies of actinomycetes with different morphology or color.(2)The fermentation broth of 15 strains of antagonistic actinomyces had strong antagonistic effect on P.parasitica,in which the inhibition rates of the fermentation broths of 8 strains against P.parasitica reached 100%.(3)12 species of actinomycetes were identified by morphological and biochemical features and 16 S rDNA analysis.They were respectively Streptomyces moderatus,S.chartreusis,S.roseoflavus,S.rochei,S.fradiae,S.aureoverticillatus,S.nobilis,S.lucensis,S.coralus,S.melanosporofaciens,S.hygroscopicus and S.amritsarensis.The 12 strains all belonged to Actinobacteria,Actinobacteria,Stretomytales,Streptomycetaceae,Streptomyces.The strong inhibitory effect of S.moderatus and S.chartreusis on plant pathogenic fungi has been reported for the first time at home and abroad.(4)588 OTUs were analyzed soil actinomycetes.Based on the results of species classification,actinomycetic community belongs to 1 phyla,5 classes,15 orders,21 families,28 genera,Among them,Actinobacteria was the dominant species.(5)The results of various analyses showed that the actinomycetes in the root circumference soil of tobacco plants are abundant,and the richness of soil actinomycetes increased with organic fertilizers.In this study,the strains of actinomycetes with strong antagonistic effect on P.parasitica were screened from the root circumference soil of tobacco plants in luoyang tobacco region,and their species were identified by morphological and biochemical features and 16 S rDNA analysis,which laid a foundation for further exploring the mechanism of biocontrol and disease control of dominant antagonistic actinomycetes,and thus effectively preventing and controlling tobacco black shank.And the diversity and community structure of soil actinomycetes were preliminarily explored by Illumina MiSeq sequencing technology to provide some theoretical reference for further screening of target actinomycetes.