黄芪根腐病拮抗菌的筛选及生防机制  

Screening of antagonistic bacteria and biocontrol mechanism of astragalus root rot

作　　者：许磊磊 白晓丽 李哲斐[1] XU Lei-lei;BAI Xiao-li;LI Zhe-fei(College of life science,Northwest A&F University,Yangling 712100,Shaanxi,Chian)

机构地区：[1]西北农林科技大学生命科学学院,陕西杨凌712100

出　　处：《西北师范大学学报（自然科学版）》2024年第2期77-85,共9页Journal of Northwest Normal University(Natural Science)

基　　金：国家自然科学基金资助项目(42277317);陕西省重大科技专项(2020zdzx-03-02-01)。

摘　　要：由Fusarium oxysporum引起的根腐病是制约黄芪产量和品质的重要因素之一,为了获得环境适应性强且拮抗效果好的黄芪根腐病生防菌,以病原真菌F.oxysporum为指示菌,通过稀释涂布法和平板对峙实验从黄芪根和根际土壤中共分离得到197株细菌,其中20株细菌对病原真菌有拮抗作用,且20株拮抗菌中优势菌为芽孢杆菌.7株拮抗菌对病原真菌生长抑制率超过35%,用这7株细菌进行盆栽试验,结果表明,菌株AS1对黄芪根腐病的防治效果最好,在接种病原菌第20 d时AS1对黄芪根腐病的防效达46.86%.进一步研究发现,菌株AS1基因组中含有伊枯草素、脂肽和杆菌霉素的编码基因,AS1处理后病原真菌孢子萌发率下降了74.4%.接种AS1第8 h后植物的苯丙氨酸解氨酶、几丁质酶、多酚氧化酶、过氧化物酶、脂氧合酶活性和茉莉酸含量较不接种对照分别提高了16.0%,21.5%,10.6%,12.6%,14.2%和97.3%.此外,AS1处理15 d后使黄芪的根长和株高分别增加了37.52%和12.78%.根据生理生化特征和16S rDNA测序发现菌株AS1归属于贝莱斯芽孢杆菌.因此,AS1是一株具有较大应用潜力的生防和促生菌株.Root rot caused by Fusarium oxysporum is one of the important factors restricting the yield and quality of Astragalus mongholicus.In order to obtain biocontrol bacteria with excellent environmental adaptability and antagonistic effect,a total of 197 bacterial strains were isolated from the roots and rhizosphere soil of Astragalus mongholicus via dilution coating method and plate confrontation using F.oxysporum as indicator pathogen.Twenty bacterial strains had the ability to inhibit the growth of fungal pathogenic mycelia through preliminary screening,and the dominant bacteria among the twenty strains were Bacillus.The inhibition rate of 7 antagonists to fungal mycelial growth was more than 35%,these 7 bacteria were selected to perform pot experiment.The results showed that strain AS1 had the best control effect on astragalus root rot,and the control effect was 46.86%on the 20th day after inoculation of AS1.Further studies showed that the genome of strain AS1 contained the coding genes of iturin,lipopeptide and Bacilysin.After AS1 treatment,the spore germination rate of pathogenic fungi decreased by 74.4%.The activities of phenylalanine ammonia lyase,chitinase,polyphenol oxidase,peroxidase,lipoxygenase and jasmonic acid content of plants inoculated with AS1 increased by 16.0%,21.5%,10.6%,12.6%,14.2%and 97.3%,respectively.In addition,after 15 days of AS1 treatment,the root length and plant height of astragalus increased by 37.52%and 12.78%,respectively.According to physiological,biochemical characteristics and 16S rDNA sequencing,the strain was found to belong to Bacillus velezensis.Therefore,AS1 is a biocontrol and growth promoting bacterium with great application potential.

关 键 词：黄芪根腐病 生防菌 诱导性系统抗性 贝莱斯芽孢杆菌 

分 类 号：S432.45[农业科学—植物病理学]