烟草根系提取物及碳水化合物对拮抗菌GZYCT-4根际定殖及青枯病菌抑菌活性的影响

Effects of tobacco root extracts and carbohydrates on rhizosphere colonization of antagonistic bacteria GZYCT-4 and its antibacterial activity to Ralstonia solanacearum

在前期获得1株对青枯病菌有拮抗效果的贝莱斯芽胞杆菌GZYCT-4的基础上,通过细菌趋化性、生物膜形成及其粗脂肽抑菌活性等试验,分析抗、感病烟草根系提取物和烟草根系分泌物中的碳水化合物对活性菌株GZYCT-4根际定殖能力及抑菌活性的影响。结果表明:GZYCT-4对烟草K326根系提取物有明显的趋化反应;烟草K326根系提取物及乳糖可促进GZYCT-4生物膜的形成,其中,添加乳糖后GZYCT-4生物膜形成基因epsD、yqxM和kinC的相对表达量分别是对照组的1.64、1.28、2.06倍。此外,蔗糖及木聚糖的添加可提高GZYCT-4脂肽粗提物对烟草青枯病菌的抑菌活性,诱导bmyB、ituC、fenD等脂肽合成基因的表达,其中蔗糖处理的GZYCT-4中bmyB、ituC、fenD相对表达量分别是对照的24.83、6.67、4.76倍。综上,这一研究为进一步阐明拮抗菌株GZYCT-4在烟草植株中的定殖特征及其生防机制提供了一定的理论基础。

Bacillus velezensis strain GZYCT-4,isolated in preliminary studies,has better antibacterial activity against Ralstonia solanacearum.On this basis,the effects of tobacco root extracts from resistant or susceptible varieties and carbohydrates in tobacco root exudates on rhizosphere colonization of GZYCT-4 and its antibacterial activity to Ralstonia solanacearum were analyzed through chemotaxis,biofilm formation and lipopeptide bacteriostasis tests.The results indicated that GZYCT-4 had obvious chemotaxis to the root extracts of resistant tobacco variety K326.The K326 root extract and lactose could promote the biofilm formation of GZYCT-4,and the expressions of genes epsD,yqxM and kinC related to biofilm formation in GZYCT-4 treated with lactose were 1.64,1.28 and 2.06 times that of control,respectively.Moreover,the sucrose and xylan improved the antibacterial activity of the crude lipopeptides of GZYCT-4 against Ralstonia solanacearum,and induced the expression of synthetic related genes such as bmyB,ituC and fenD.The relative expressions of bmyB,ituCand fenDof GZYCT-4 treated with sucrose were 24.83,6.67 and 4.76 times that of control,respectively.The results provide a theoretical basis for further elucidating the colonization characteristics of antagonistic strain GZYCT-4 in tobacco plants and its biological control mechanism.