玉米茎腐病拮抗放线菌的筛选及抑菌促生活性鉴定

以禾谷镰孢菌为靶标，采用稀释培养法和平板对峙法从采集的玉米连作土壤中分离筛选出具有拮抗活性的放线菌菌株，选取1株拮抗效果最佳的菌株进行形态学、生理生化特征和系统发育分析，并对其进行抑菌活性试验，挖掘对玉米茎腐病致病菌-禾谷镰孢（Fusarium graminearum）有较高拮抗效果的根际促生菌资源。结果表明，玉米连作土壤中分离得到5株禾谷镰孢菌拮抗菌株，其中菌株G1为高效拮抗菌株。经形态学、生理生化结合16S rDNA将菌株鉴定为公牛链霉菌（Streptomyces tauricus）。拮抗菌株G1发酵液对禾谷镰孢的菌丝生长和孢子萌发均有明显的抑制作用，具有分泌吲哚乙酸和异羟肟酸型铁载体的能力。公牛链霉菌G1在由禾谷镰孢病菌引起的玉米茎腐病防治中具有良好的应用开发潜力。

Screening of Antagonistic Actinomycetes against Corn Stalk Rot Disease and Identification of Antimicrobial Activity

In order to explore the resources of rhizosphere growth-promoting bacteria that have a high antagonistic effect against Fusarium graminearum, the pathogen of corn stalk rot, Fusarium graminearum was used as the target, and the dilution culture method and the plate confrontation method were adopted. An actinomycete strain with antagonistic activity was isolated and screened from the collected corn continuous cropping soil, and a strain with the best antagonistic effect was selected for morphological, physiological and biochemical characteristics and phylogenetic analysis, and the antibacterial activity test was carried out. The results showed that five Fusarium graminearum antagonistic strains were isolated from the continuous corn cropping soil, among which strain G1 is a highly effective antagonistic strain. The strain was identified as Streptomyces tauricus through morphological, physiological, and biochemical combination of 16S rDNA. The fermentation broth of the antagonistic strain G1 has a significant inhibitory effect on the mycelial growth and spore germination of Fusarium graminearum. The antagonistic strain G1 could secrete indole acetic acid and hydroxamic acid-type siderophores. In summary, Streptomyces bull G1 has a good application and development potential in the control of corn stalk rot caused by Fusarium graminearum.