水拉恩氏菌JZ-GX1对杨树溃疡病菌的拮抗作用

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

【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(1 584.75μmol/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0.408μmol/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。

【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-GX1 strain showed better antagonistic ability to Cytospora chrysosperma with77.87% 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（1 584.75μmol/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.