Orser C, Staskawicz B J, Panopoulos N J, Dahlbeck D, Lindow S E
J Bacteriol. 1985 Oct;164(1):359-66. doi: 10.1128/jb.164.1.359-366.1985.
Epiphytic populations of Pseudomonas syringae and Erwinia herbicola are important sources of ice nuclei that incite frost damage in agricultural crop plants. We have cloned and characterized DNA segments carrying the genes (ice) responsible for the ice-nucleating ability of these bacteria. The ice region spanned 3.5 to 4.0 kilobases and was continuous over this region in P. syringae Cit7R1. The cloned fragments imparted ice-nucleating activity in Escherichia coli. Substantial increases in the nucleating activity of both E. coli and P. syringae were obtained by subcloning the DNA fragments on multicopy plasmid vectors. Southern blot analysis showed substantial homology between the ice regions of P. syringae and E. herbicola, although individual restriction sites within the ice regions differed between the two species.
丁香假单胞菌和草生欧文氏菌的附生菌群体是导致农作物遭受霜冻损害的冰核的重要来源。我们已经克隆并鉴定了携带负责这些细菌冰核形成能力的基因（ice）的DNA片段。冰核区域跨度为3.5至4.0千碱基，在丁香假单胞菌Cit7R1的该区域内是连续的。克隆的片段赋予大肠杆菌冰核形成活性。通过将DNA片段亚克隆到多拷贝质粒载体上，大肠杆菌和丁香假单胞菌的成核活性都有显著提高。Southern印迹分析表明，丁香假单胞菌和草生欧文氏菌的冰核区域之间存在显著同源性，尽管两个物种冰核区域内的个别限制性酶切位点有所不同。
