抗生素溶杆菌13-6对玉米小斑病的生防作用机制初步研究

 玉米小斑病是玉米生产中的重要病害之一,本研究利用传统植物病理学和荧光定量PCR方法,研究抗生素溶杆菌对玉米小斑病菌(Bipolaris maydis)的生防效果和作用机制,为玉米小斑病的生物防控提供理论依据。结果显示,抗生素溶杆菌13-6对玉米小斑病菌丝生长和孢子萌发具有显著抑制作用,造成菌丝顶端生长受阻、表面粗糙,部分菌丝破裂,代谢粗提物抑制孢子萌发率高达92.19%,PI荧光染色显示病原菌孢子破裂并死亡。温室叶面喷施13-6发酵液、发酵液粗提物后显著降低玉米小斑病病情指数,相对防效分别达到42.43%和68.06%。诱导抗性实验表明:13-6对玉米小斑病的诱导防效达49.57%。玉米植株体内相关抗性基因表达结果显示,在灌根处理3 d后,抗病相关基因PR1和PR5、脂氧合酶LOX、乙烯受体ETR1均被激活表达,9 d达到最大值。研究证实抗生素溶杆菌13-6对玉米小斑病具有较好的生防效果,直接喷施可减缓玉米小斑病的发生,灌根施用使植株产生诱导抗性。

Biocontrol mechanism of Lysobacter antibioticus 13-6 on southern corn leaf blight

Southern corn leaf blight (SCLB), caused by the pathogen Bipolaris maydis, is one of the serious threats in maize production. In this study, the bacterium Lysobacter antibioticus 13-6 was used as a biocontrol agent to control the southern corn leaf blight (SCLB). Traditional plant pathology methods and fluorescence quantitative PCR were used to study the biocontrol efficacy and the mechanism of L. antibioticus 13-6 on B. maydis. The results showed that the L. antibioticus 13-6 had a significant inhibitory effect on the mycelial growth and conidial germination of B. maydis, such as blocking of the top growth of hyphae, rough surface, and rupture of part of the hyphae. The metabolic crude extract of L. antibioticus 13-6 inhibited the germination rate of conidia by 92.19%. The fluorescence staining of PI showed that the conidia of B. maydis were broken and died. After spraying the L. antibioticus 13-6 fermentation liquid or crude extract on the leaves, the disease index (DI) of SCLB was significantly reduced. The control efficacy reached up to 42.43% and 68.06%, respectively. Root irrigation assay showed that the control efficacy of of L. antibioticus 13-6 on southern corn leaf blight was 49.57%. Expression profiling of the defense-related marker genes showed that the defense-resistant genes PR1 and PR5, lipoxygenase LOX and ethylene receptor ETR1 were all activated, and reached the maximum value at 9^th day after the roots treated with L. antibioticus 13-6. The results of this study suggest that the application of the L. antibioticus 13-6 could reduce the incidence of southern corn leaf blight, and root irrigation could induce systemic resis-tance of the plants.