【作者】 黄珊珊；

【导师】 文景芝；

【作者基本信息】 东北农业大学 ， 植物病理学， 2008， 硕士

【摘要】 本试验采用常规方法分离大豆根腐病病原菌,并从大豆根际中筛选大豆根腐病菌拮抗菌,利用磷脂脂肪酸法确定大豆根腐病菌拮抗菌的分类地位,然后利用基于16S rDNA特异性扩增的DGGE技术,结合传统方法,来研究施用种衣剂后大豆根际细菌遗传多样性和非靶标有益微生物中的主要生防菌随大豆生育期而消长变化的规律,得到了不同处理条件下的根际细菌DNA序列多样性之间的差异,分析了种衣剂对大豆根际细菌多样性及对根腐病生防菌的影响强度和影响的持续性,为大豆根际其他功能微生物的进一步研究奠定了基础。本研究获得的主要结论如下:1.大豆根际具有抑菌效果的菌株占分离菌株总数的25%,并且细菌的抑菌效果较放线菌的抑菌效果好。由鉴定结果可知,8株生防细菌中主要有枯草芽孢杆菌(Bacillus subtilis),荧光假单孢菌(Pseudomonas spp.)等,放线菌中主要起生防作用的是链霉菌(Streptomycesspp.)。2.宁南霉素、咯菌腈、甲霜灵和多克福对大豆根际细菌多样性均产生影响。试验前期,除低浓度甲霜灵外其他处理组均对大豆根际细菌产生较强的抑制作用,甲霜灵高浓度和常规浓度的抑制作用较小。试验中期,不同种衣剂对大豆根际细菌多样性的影响强度不同,3种浓度的多克福对根际细菌多样性的影响较小,接近对照水平,其他3种种衣剂至少有2种浓度对根际细菌种群结构在遗传上的影响一致。后期,宁南霉素处理组最先恢复到对照水平,然后依次是多克福和甲霜灵,咯菌腈。3.试验前期,4种种衣剂均抑制生防菌Pseudomonas sp.的生长,之后,各种种衣剂对该种生防菌稍有促进作用,最后恢复到对照水平。4种种衣剂对生防菌Bacillus sp.的影响不大,但甲霜灵在试验前期对该种生防菌具有促进作用。4.4种种衣剂在常规使用浓度下,多克福和甲霜灵药效持续到第75d。施用宁南霉素后的第61d、68d、75d、82d的土壤细菌在遗传上相近,表明宁南霉素处理从第61d开始恢复到正常水平。施用咯菌腈后的第68d和75d的根际细菌种群在遗传上较近,施药后期对大豆根际细菌的影响趋于稳定,影响较小,直至第82d无变化。更多还原

【Abstract】 Soybean root rot pathogens were isolated by conventional methods and the test screened of antagonistic bacteria and actinomyces to root rot pathogens from the soybean rhizosphere,then the antagonistic bacteria and actinomyces were identified by phospholipid fatty acid method and 16S rDNA sequencing.This experiment studied the genetic diversity of bacterial community in soybean rhizosphere and the dynamic of biocontrol bacterials against soybean root rot pathogens with DGGE,combining with dilution method after treatment with different concentrations of Metalaxyl, Carbofuran-Carbendazim-Thiram,Ningnanmycin and Fludioxonil.We gained the changes and differences of the amount of genetic diversity and biocontrol bacterial,and analyzed strength and persistent of the influence of seed coatings on the genetic diversity of bacterial and biocontrol bacterials in soybean rhizosphere,and tried to provide the reference for the research of other function microorganism.The main conclusions of this paper were as follows:1.25%of the total isolates belonged to antagonistic bacteria and actinomyces,and antibacterial effect of bacteria were better than that of actinomyces.From the identification,we could see the main bacterial strains were Bacillus subtilis and Pseudomonas spp..The main actinomyces were Streptomyces spp..2.The four kinds of seed coatings all influenced on the genetic diversity of bacterial in soybean rhizosphere.At the early period,the four kinds of seed coatings inhibited the diversity of bacterial in soybean rhizosphere except of Low-concentration of Metalaxyl,and inhibition of middle-concentration and high-concentration of Metalaxyl is smaller.At the middle of the experiment,different kinds of seed coatings had different effects on the diversity of soybean rhizospheric bacterials,the influence strength of the three concentrations of Carbofuran-Carbendazim-Thiram is smaller,closing to the normal level,at least the influence strength of two concentrations of the other seed coatings were similar.At the later period,the effects of Ningnanmycin recovered to the normal level,the influence of Fludioxonil is smaller than the others until recovered to the normal level. 3 At the 22nd day,all the treatments inhibited propagation of Uncultured Pseudomonas sp., then all the treatments promoted for propagation of it slightly,and recovered to the normal level at last.The four kinds of seed coatings influenced on Bacillus sp.very little,but at the early period, Metalaxyl promoted for propagation of Bacillus sp..4.The effect of middle-concentration of Carbofuran-Carbendazim-Thiram and Metalaxyl sustained on the 75th day.The effect of middle-concentration of Ningnanmycin sustained on the 61th day.The heredities of soybean rhizospheric bacteria were similar after treatment with Fludioxonil on the 68th day and the 75th day,the effect of Fludioxonil was stable and smaller at last until unchanged on the 82th day.更多还原