Isolation And Identification Of Biocontral Bacteria In Zhangye Corn Seed Production Base And Analysis Of Biocontrol Effect

Zhangye City,Gansu Province is a national corn hybrid seed production base.The area of hybrid corn seed base is stable at about 1 million mu,with an annual output of 450 million kilograms of corn seeds,accounting for more than 50%of the national annual corn field.Due to the corn planting in successive years,the corn seed production base has frequent disease.Among them,corn top rot and ear rot once seriously affect the corn seed production and seed quality.The chemical control effect is not good,but also brings hidden dangers to the environment and ecology as well as human and animal safety.Biological control has the advantages of broad spectrum,high efficiency,environmental protection and safety,and has received more and more attention in recent years.In this paper,the main fungal pathogens of maize isolated from the soil and corn plants of Zhangye corn were collected in this laboratory,and the antagonistic bacteria were isolated from the soil and corn plants.Screening and identification were carried out by antagonistic morphological identification and 16S-rDNA amplification sequencing analysis.A broad-spectrum and high-efficiency Bacillus subtilis was selected to identify its effects on maize top rot and cotton verticillium,and its extracellular metabolites were analyzed.The main results are as follows:1.From the corn stalks and soil recovered from Zhangye City,Gansu Province,112 biocontrol bacteria with different 16S-rDNA sequences were isolated and identified,and their pathogens against Fusarium oxysporum were identified.Antagonism of Fusarium oxysporum,Fusarium oxysporum and the pathogen of corn ear rot,Fusarium oxysporum and Verticillium dahliae,a pathogen of cotton Verticillium dahliae,of which 20 isolates are above Pathogenic bacteria have a bacteriostatic effect.2.Select a strain of Bacillus subtilis with broad spectrum of antibacterial activity and stable antibacterial effect.The 16S-rDNA sequence is highly homologous to Bacillus subtilis strain 2KL1.This strain has very good effect on maize top rot and cotton verticillium wilt.Good control effect.It can colonize the stems and roots of corn and cotton,can resist the invasion and expansion of plant disease resistance,and can promote the growth of cotton plants and promote the early flowering of cotton.3.Bacillus subtilis 2KL1 extracellular metabolism of crude protein has a good antibacterial effect,and high thermal stability.4.The extracellular metabolites produced by the strain were analyzed by LC-MS and identified as containing various lipopeptide antibiotics such as surfactin,iturin and fengycin.