Function of the genes specifically expressed in the genetic tumors

发根农杆菌负责形成不定根，即毛状根。该病的分子基础是Ri质粒的DNA片段（Rirol基因）转移到植物基因组中。在未转化的白烟基因组中，检测到与Rirol基因同源的Ngrol基因。我们已经报道了N. glauca（-组）和N. langsdorffii（+组）在F1植物上自发形成的遗传肿瘤组织中表达的NgrolB和NgrolC基因。在本研究中，我们发现NgORF13在遗传肿瘤中也有表达。ngrob、NgrolC和NgORF13的表达分别受植物激素、生长素、细胞分裂素和茉莉酸的调控。另一方面，转基因烟草NgORF13和NgrolC均促进了rirol介导的毛状根诱导。在35S启动子控制下，NgORF13和NgrolC的过表达引起转基因烟草的形态异常。然而，在这些植物上没有出现肿瘤。为了明确Ngrol基因是否为烟草群体的肿瘤因子，我们分别将ngrob ~ ORF14、35S-NgrolC、35S-NgORF13等嵌合基因引入到N. langsdorffii中。在这些病例中也未观察到肿瘤的形成。结果表明，Ngrol基因不是-组肿瘤形成的唯一因素。这些转基因植物对植物生长调节剂的不同反应表明，Ngrol基因可能与其他未知因子协同作用于烟草群中遗传肿瘤的形成

Agrobacterium rhizogenes is responsible for the formation of adventitious roots known as hairy roots. The molecular basis of this disease is the transfer of the DNA segments (Rirol genes) of Ri plasmid into the plant genome. In the genome of untransformed Nicotiana glauca, Ngrol genes, homologous to Rirol genes, were detected. We have already reported NgrolB and NgrolC genes expressed in the genetic tumor tissues spontaneously developed on F1 plants between N. glauca (-group) and N. langsdorffii (+group).In this study, we found NgORF13 also expressed in the genetic tumors. Furthermore, the expression of NgrolB, NgrolC and NgORF13 was found to be regulated by the plant hormones, auxin, cytokinin and jasmonic acid, respectively. On the other hand, the transgenic N. tabacum (-group) revealed both NgORF13 and NgrolC promoted the Rirol-mediated hairy root induction. Overexpression of NgORF13 and NgrolC, under the control of 35S promoter, provoked morphological abnormalities in the transgenic N. tabacum. No tumors, however, developed on these plants.To clarify whether or not the Ngrol genes are the tumor factor in group of tobacco, chimeric genes, such as NgrolB〜ORF14, 35S-NgrolC, 35S-NgORF13, were separately introduced into N. langsdorffii. The tumor formation also couldn't be observed in these cases. The results indicate that Ngrol genes aren't a unique factor of tumor formation in -group. The varied responses to plant growth regulators of these transgenic plants suggests, however, Ngrol genes cooperated with other unknown factor in -group tobacco might function on genetic tumor formation