水拉恩氏菌JZ-GX1对杨树溃疡病菌的拮抗作用

【目的】探讨根际促生细菌水拉恩氏菌(Rahnella aquatilis)JZ-GX1菌株对杨树溃疡病菌的拮抗作用。【方法】采用平板对抗、胞外代谢产物抑菌率测定、SEM电镜观察以及以‘NL895'杨(Populus×euram ericana CL‘NL895')1年生扦插苗为对象,采用茎干涂布和菌剂灌根处理等检测JZ-GX1菌株对杨树溃疡病的防治效果。【结果】水拉恩氏菌JZ-GX1菌体对杨树溃疡病菌金黄壳囊孢(Cytospora chrysosperma)和拟茎点霉(Phomopsis sp.)的抑菌效果明显,对七叶树壳梭孢(Fusicoccum aesculi)无抑制作用; 菌株胞外代谢产物对金黄壳囊孢也具有较好的抑菌效果,抑菌率达77.87%。在茎干涂布和菌剂灌根处理下,杨树盆栽苗的发病率较对照低,其中灌根法对金黄壳囊孢引起的溃疡病防效为84%。电镜观察发现,水拉恩氏菌JZ-GX1菌株发酵液能使金黄壳囊孢菌丝变稀且扭曲变形、分支增多; 抗菌物质检测可知,JZ-GX1菌株能够产生嗜铁素、纤维素酶和磷酸酯酶; 对病原菌细胞膜透性、可溶性糖和MDA有较大影响,处理后的金黄壳囊孢菌丝细胞的可溶性糖浓度(1 584.75 μmol/L)较对照降低,细胞膜透性(相对电导率达77.08%)和MDA含量(浓度达0.408 μmol/L)均高于对照,且JZ-GX1菌株能够在杨树体内定殖。【结论】水拉恩氏菌JZ-GX1菌株具有良好的对杨树溃疡病的生防潜力。

Antagonism of plant growth-promoting bacteria Rahnella aquatilis JZ-GX1 to canker in poplar

[Objective] This study is to investigate the antagonistic ability and mechanism of Rahnella aquatilis JZ-GX1 strain against pathogens causing poplar canker to improve the biocontrol of polar canker.[Method] The control efficiency of JZ-GX1 strain was studied by antagonistic testing in dural culture,determining of the extracellular metabolites inhibitory rate,observation under SEM (scanning electron microscopy) and inoculation via root pouring and stem coating on one-year-old cuttings of ‘NL 895'polar (Populus×euramericana CL‘ NL895').[Results] The results showed that R.aquatilis JZ-GX1 strain had significant antagonistic ability to C.chrysosperma and Phomopsis sp.,but not to Fusicoccum aesculi.The extracellular metabolites of JZ-GXl strain showed better antagonistic ability to Cytospora chrysosperma with 77.87％ inhibitory rate.The occurrence rate of the disease was lower than the control under root pouring and stem coating treatment,and the control efficiency of JZ-GX1 strain against C.chrysosperma was 84％.The fermented suspension of JZ-GX1 strain can change the morphology of the hyphae of C.chrysosperma to be more thinned,twisted and more branches under SEM.JZ-GX1 strain also can produce siderophore,cellulase and phosphatase,which significantly affect the cell membrane permeability,the concentration of soluble sugar and MDA.The concentration of soluble sugar (1584.75 μmol/L) decreased comparing to the control after treatment and the cell membrane permeability (with relative conductance of 77.08％) and MDA content increased MDA concentration of 0.408 μmol/L).JZ-GX1 strain can colonize in poplar.[Conclusion] Rahnella aquatilis JZ-GX1 strain had a potential to be used as bio-control agent against poplar canker.