荧光假单胞菌PEF-5#18防控番茄枯萎病的定殖机理

通过电转法成功将EGFP表达质粒p EGFP20转入对番茄枯萎病具有优良防病效果的荧光假单胞菌PEF-5#18体内,并研究了该生防菌在番茄根际土壤与植株根、茎内部组织的定殖情况。结果表明,处理25 d后,标记型与野生型生防菌处理均能有效控制番茄枯萎病害并增加植株鲜、干重量。与病原菌阳性对照相比,野生型菌株的防治效果为76.92%,鲜重增加194.10%,干重增加564.71%;接种后的PEF-5#18能良好定殖于番茄根际土壤并扩展进入植物根茎内部生长,其分布数量呈现出根际土壤(1.05×106 CFU/g)根(6.75×104 CFU/g)茎(1.25×102 CFU/g);与病原菌阳性对照相比,接种PEF-5#18对番茄根际土壤的可培养细菌总数影响差异不显著,但可显著提高根(增幅为8.42%)、茎(增幅为14.78%)内的可培养细菌总数以及根际土壤pH(增幅为1.61%);接种PEF-5#18能显著降低根际土壤与根、茎内病原菌侵染数量;激光共聚焦镜检发现,接种25 d后,PEF-5#18能大量分布于番茄根系表面、根内木质部、根内皮层细胞、根内细胞间隙、茎内维管及其周围细胞。

Colonization of Pseudomonas fluorescens PEF-5#18 to Control Fusarium Wilt Disease on Tomato

In order to study the colonization in rhizosphere soil as well as root-stem inside,plasmid pEGFP20 expressing green fluorescens protien was transferred into wild type Pseudomonasfluorescens PEF-5#18 with great effect against Fusarium wilt disease on tomato by electrophoretic transfer method.The results indicated that both wild type and marked P.fluorescens PEF-5#18 bio-control treatments could remarkably control Fusarium wilt disease on tomato with the efficiency of 76.92％ and increase plant fresh (194.10％) or dry weight (564.71％) after 25 days,if compared with Forl positive treatment.Inoculated P fluorescens PEF-5#18 could colonize in rhizosphere soil and extend into tomato root-stem inside,and the distribution amounts ranked as:rhizosphere soil (1.05 × 106 CFU/g) ＞ root (6.75 × 104 CFU/g) ＞ stem (1.25 × 102 CFU/g).Compared with pathogen positive control,the pathogen population was remarkably reduced in rhizosphere soil and root-stem inside,the cultivable bacteria population (increased 8.42％ inside root and 14.78％ inside stem) and pH value (increased 1.61％) were remarkably increased.Confocal microscopy observation demonstrated that P.fluorescens PEF-5#18 existed on root surface,root xylem,root endodermis cells,root intercellular space,stem vascular tissue cells and the cells around.