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冰核细菌是自然界中冰核活性最强的异源冰核(-1~-5℃),已成为一种重要的生物资源.大量研究证明,利用冰核细菌促冻杀虫在理论上已确凿无疑,但难以应用野生型冰核细菌冻杀田间和仓储越冬害虫,其因有二:其一,野生型冰核细菌不能在昆虫肠道内长期稳定增生定殖,易被排泄体外而丧失冻杀效果;其二,这些冰核细菌在植物体上附生定殖能力强,田间施用后易诱发霜冻害.为解决这些阻碍促冻杀虫应用中的难题,利用自行分离的细菌冰核基因iceA,构建了携带该基因、能进行接合转移和Tn5转座作用的工程质粒mob-Tn5-iceA,又利用该工程质粒将冰核基因iceA整合到阴沟肠杆菌(Enterobacter cloacae)染色体DNA上,成功地构建了在无选择压力下冰核基因仍稳定存在并有效表达冰核活性的促冻杀虫基因工程菌.经应用实验证明,解决了阻碍促冻杀虫应用中的难题,为防治我国三北地区农林果树和仓储主要越冬害虫,开辟了一条生防新途径.
Ice nucleus is the most active ice nucleus in nature, allogenic ice nuclei (-1 ~ -5 ℃), has become an important biological resources.Numerous studies have shown that the use of ice nucleotidase freeze-thaw in theory has been Indeed, but it is difficult to apply the wild-type ice-core bacteria to frost the field and storage of winter pests, because there are two: First, the wild type of ice-core bacteria can not colonize long-term stable colonization in the insect gut, easily excreted and lost to freeze Killing effect; Second, these ice nucleation bacteria in plant epigenetic colonization ability, easy to induce frost damage after field application.In order to solve these problems impede the application of freeze-thaw insecticide, the use of self-isolated bacterial ice nuclear gene iceA to construct the engineered plasmid mob-Tn5-iceA carrying this gene, capable of performing junctional transfer and Tn5 transposon, and using this engineered plasmid to integrate ice-ice gene iceA into the Enterobacter cloacae chromosomal DNA successfully To build the freeze-thaw insecticidal genetic engineering bacteria that the ice nucleus gene still exists in the absence of selective pressure and effectively expresses the activity of ice nuclei.It has been proved by application experiments that the problems in the application of freeze-thaw insecticides are solved, North region of agriculture Fruit trees and warehousing major wintering pests, biological control has opened up a new way.