Campell B R, Town C D
Biology Department, Case Western Reserve University, Cleveland, Ohio 44106-7080.
Plant Physiol. 1992 Dec;100(4):2018-23. doi: 10.1104/pp.100.4.2018.
To investigate the molecular mechanisms of hormonal control of growth, we constructed a subtracted cDNA library enriched for sequences expressed more in a hormone-autonomous, radiation-induced tumor tissue line of Arabidopsis thaliana than in normal, hormone-dependent callus. Ten cDNA clones, which are expressed 1.3- to 10-fold more in the tumor line, were isolated and partially characterized. The clones differ greatly in their level of expression in tumor tissue and in their pattern of expression in plant organs. Southern blot hybridization and sequence analysis showed that this group contains three pairs of closely related clones. Northern blot analysis indicates that one pair of clones represents two members of a gene family that are expressed in different plant organs. One of the isolated sequences shows strong sequence similarity to a cDNA encoding a lipid transfer protein. Two sequences are highly similar to those of previously described membrane channel proteins but have different organ specificities. Two other cDNAs have significant sequence similarity to glycine-rich proteins and hydroxy-proline-rich glycoproteins. When used to probe Southern blots, none of the cDNAs identified polymorphisms between tumor and callus DNA, which might be expected if their overexpression were due to local genome rearrangements induced by radiation. The diversity observed among these 10 clones suggests that some are likely to be involved in tumorous growth and not simply specific to a certain cell or tissue type present in the tumor.
为了研究激素对生长控制的分子机制，我们构建了一个消减cDNA文库，该文库富集了在拟南芥的激素自主型、辐射诱导肿瘤组织系中比在正常的、激素依赖型愈伤组织中表达更多的序列。分离出了10个在肿瘤系中表达量高1.3至10倍的cDNA克隆，并对其进行了部分特征分析。这些克隆在肿瘤组织中的表达水平以及在植物器官中的表达模式差异很大。Southern杂交和序列分析表明，该组包含三对密切相关的克隆。Northern印迹分析表明，其中一对克隆代表一个在不同植物器官中表达的基因家族的两个成员。其中一个分离出的序列与编码脂质转移蛋白的cDNA具有很强的序列相似性。两个序列与先前描述的膜通道蛋白高度相似，但具有不同的器官特异性。另外两个cDNA与富含甘氨酸的蛋白和富含羟脯氨酸的糖蛋白具有显著的序列相似性。当用于探测Southern印迹时，没有一个cDNA能识别出肿瘤和愈伤组织DNA之间的多态性，如果它们的过表达是由于辐射诱导的局部基因组重排，这是可以预期的。在这10个克隆中观察到的多样性表明，其中一些可能参与肿瘤生长，而不仅仅是肿瘤中存在的特定细胞或组织类型所特有的。
