Rong L, Karcher S J, O'Neal K, Hawes M C, Yerkes C D, Jayaswal R K, Hallberg C A, Gelvin S B
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
J Bacteriol. 1990 Oct;172(10):5828-36. doi: 10.1128/jb.172.10.5828-5836.1990.
We used the transposon Mu dI1681 to identify genes on the Agrobacterium tumefaciens chromosome that are inducible by extracts from carrot roots. One such locus (picA, for plant inducible chromosomal), harbored by A. tumefaciens At156, was inducible 10- to 50-fold by these extracts. Mutation of picA had no detectable effect upon bacterial growth or virulence under laboratory assay conditions. However, A. tumefaciens cells harboring a mutated picA locus aggregated into long "ropes" when incubated with pea root tip cells. Such aggregation was not displayed by the parental strain A. tumefaciens A136. A preliminary characterization of the inducing compound in the carrot root extract suggests that the active substance is an acidic polysaccharide that is most likely derived from the pectic portion of the plant cell wall.
我们使用转座子MudI1681来鉴定根癌土壤杆菌染色体上可被胡萝卜根提取物诱导的基因。根癌土壤杆菌At156所携带的一个这样的位点（picA，即植物诱导染色体基因），被这些提取物诱导了10到50倍。在实验室检测条件下，picA突变对细菌生长或毒力没有可检测到的影响。然而，携带突变picA位点的根癌土壤杆菌细胞在与豌豆根尖细胞一起孵育时会聚集成长长的“绳索”状。亲本菌株根癌土壤杆菌A136不会出现这种聚集现象。对胡萝卜根提取物中诱导化合物的初步表征表明，活性物质是一种酸性多糖，很可能来源于植物细胞壁的果胶部分。
