Study On The Mechanism Of Cotton Endophytic And Rhizosphere Antagonism Against Verticillium Wilt

Cotton is the pillar industry in Xinjiang agriculture,however,Verticillium wilt has become one of the main restrictive factors in cotton production and fiber quality in xinjiang,endophytic and rhizosphere bacteria are considered to be the most potential strains for biological control Verticillium wilt.In this study,we selected indigenous endophytic and rhizosphere antagonistic bacteria(Bacillus vanillea SMT–24,Bacillus velezensis BHZ–29,Bacillu subtilis SHT–15,Bacillus atrophaeus SHZ–24)in Xinjiang to explore their metabolic antifungal substances,extracellular enzyme,siderophore,and system–induced resistance to cotton,the aim is to clarify the mechanism of the four antagonistic bacteria against cotton verticillium wilt,and provide theoretical support for better,more targeted and more scientific control of cotton Verticillium wilt.The results are as follows:1.The active antifungal substances of SMT–24,BHZ–29,SHZ-15 and SHZ–24 strains maintain high antifungal activity at pH 5.0–9.0,UV irradiation below 8 h and below 100 °C.SMT–24,BHZ-29 strain produce protein antifungal substances,SHT-15 strain produces protein,lipopeptide,and lipid antifungal substances,SHZ-24 strain produces protein,lipid antifungal substances.2.SMT–24,BHZ–29,SHT–15,and SHZ–24 strains all produce glucanase,protease,and cellulase,and hardly produce chitinase.SHT–15 strain produces chitinase,glucanase,and protease,and produce low cellulase.3.SMT–24,BHZ–29,SHT–15,and SHZ–24 strains all produced siderophore,the type of siderophore was catechol,and the four antagonistic strains had lower ability to produce siderophore,the difference in inhibition zone size of the fermentation sterile filtrate treated with 0,10,20 ?mol/L iron ions was not significant.4.SMT–24,BHZ–29,SHT–15,and SHZ–24 strains could reduce the disease index,inhibit the growth of V.dahliae,colonize the soil well,promote the growth of cotton plants,and induce resistance to cotton systems.In summary,the four strains of antagonistic bacteria can produce antifungal substances,induce the increase of plant defense enzyme activity,and reduce the incidence of verticillium wilt.