利用GFPuv标记研究人参铜绿假单胞菌对人参根、叶片的侵染和扩展

Infection and Expansion of Ginseng Roots and Leaves by Pseudomo⁃nas aeruginosa Labelled with GFPuv

构建具有GFPuv标记的人参铜绿假单胞菌(Pseudomonas aeruginosa)PA2和AT3菌株,观察其在人参根部、叶片的侵染和扩展过程。结果表明:各标记菌株与野生型菌株的生物学特性无明显差异。接种在人参根部的各标记菌株细菌会先吸附在有伤口、裂口和皱褶的表皮处再逐渐向韧皮部及形成层扩散,其中分离自人参根部的菌株PA2-GFPuv的侵染率、扩散速度和致病力均高于分离自叶部菌株AT3-GFPuv;接种在叶部的各标记菌株细菌沿叶脉逐渐由主脉向侧脉扩展最终蔓延至叶缘,其中菌株AT3-GFPuv的侵染率、扩散速度和致病力均高于菌株PA2-GFPuv。定殖在人参根部的2菌株细菌数以较低初始量持续增长,其中PA2-GFPuv细菌数始终高于AT3-GFPuv;定殖在人参叶部的各菌株细菌数均呈先增长后下降趋势,其中AT3-GFPuv细菌数始终高于PA2-GFPuv;而在人参根际土壤中存活的2菌株细菌数均以较快速率持续下降。利用具有GFPuv标记的人参铜绿假单胞菌菌株可以直观地观察病原菌在人参根部、叶片的侵染和扩展过程,这为进一步研究病害的侵染发生规律奠定了基础。

To study the infection and expansion of Pseudomonas aeruginosa in roots and leaves of ginseng,strains PA2 and AT3 of P.aeruginosa with GFPuv labeled were constructed.The biological characteristics of the labeled strains were not significantly different from those of the original strains.When the strains were inoculated into the root of ginseng,the bacteria first colonized at the epidermis with wounds,cracks,and folds,and then gradually invaded to phloem and cambium.The infection rate,extension rate and pathogenicity of strain PA2-GFPuv isolated root were higher than those of the leaf source strain AT3-GFPuv.When inoculated in the petiole,the bacteria could extend from the main vein to the lateral vein and eventually spread to the leaf blade margin.The infection rate,ex⁃tension rate and pathogenicity of strain AT3-GFPuv isolated root were higher than those of the leaf source strain PA2-GFPuv.The number of bacteria colonized in the root of ginseng continued to in⁃crease at a lower initial amount,and that of PA2-GFPuv was higher than that of AT3-GFPuv.The number of bacteria colonized in the leaf of ginseng increased at first and then decreased,and that of AT3-GFPuv was higher than that of PA2-GFPuv.The number of colonies in the soil continued to de⁃crease at faster rate.P.aeruginosa strains expressing GFPuv gene can be used to directly observe in⁃fection and expansion of the bacteria in roots and leaves of ginseng.It provides a basis for further re⁃search about the infection and occurrence regularity of the disease.