Search for genes involved in plant tumor and teratoma formation

根癌农杆菌是一种土壤细菌，能在多种植物上引起根癌病。肿瘤组织在培养基上表现出各种表型。我们假设在这些组织中，参与植物分化的基因可以被诱导或抑制，因此目前的计划是分离和鉴定这些基因。我们首先在烟草植株中导入生长素和细胞分裂素生物合成基因，以及调节这些植物生长物质作用的6b基因，从而在烟草植株中产生了形成芽和无组织的愈伤组织。从这些组织中合成互补DNA，并通过差异杂交和差异显示技术筛选差异表达。5个克隆和4个克隆分别在生芽愈伤组织和无组织愈伤组织中优先表达。前一个克隆与胡萝卜14KD蛋白、烟草花叶病毒侵染相关基因SAR8.2、烟草热休克蛋白、叶绿素a辅基蛋白psaB和烟草核糖核蛋白基因同源。后者与烟草几丁质酶、拟南芥核糖体蛋白L29、黑麦过敏蛋白Lolp1相似，并命名为1-22A，特别是14KD蛋白基因已被报道与胡萝卜细胞再生有关，因此我们在CaMV35S启动子的反义控制下克隆了我们的同源物，并将其导入烟草。不幸的是，由此产生的转基因植株没有表现出任何表型异常。然而，创伤诱导了该基因的表达，这表明14KD蛋白基因参与了应激反应。最后，psaB和核糖核蛋白基因似乎是叶绿体发育所必需的，需要进一步的研究来确定叶绿体和整个植物发育的关系。

A soil bacterium Agrobacterium tumefaciens induces crown gall disease on many plants. Tumorous tissues display various phenotypes on the culture medium. We assumed that in these tissues, the genes involved in plant differentiation could be induced or repressed, and thus current project is directed to isolation and characterization of such genes. We first generated shoot-forming and unorganized calli in tobacco plants upon introduction of auxin and cytokinin biosynthesis genes, and 6b gene which modulates the effects of these plant growth substances. Complementary DNA was synthesized from these tissues and screened for differential expression by differential hybridization and differential display techniques. Five clones and four clones were found to be preferentially expressed in shoot-forming callus and unorganized callus respectively. The former clones were homologous to the genes encoding 14kD protein from carrot, SAR8.2 associated with tobacco mosaic virus infection, heat shock protein, chlorophyll a apoprotein psaB,and ribonucleoprotein from tobacco. The latter clones were similar to tobacco chitinase, ribosomal protein L29 from Arabidopsis, allergenic protein Lolpl from rye, and as yet unknown clone termed 1-22A.Particularly, the 14kD-protein gene has been reported to be associated with regeneration of carrot cells, and hence we cloned our homologue under the control of CaMV35S promoter in an antisense orientation, and introduced to tabacco. Unfortunately, resulting transgenic plants did not show any phenotypic abnormality. However, the gene expression was induced by wounding, which suggest that the 14kD-protein gene is involved in stress response. Finally, the psaB and ribonucleoprotein gene seem to be required for chloroplast development, and further investigation is necessary to determine the relationship between plastid and total plant development.