Tinland B, Fournier P, Heckel T, Otten L
Institute of Plant Molecular Biology of the C.N.R.S., Strasbourg, France.
Plant Mol Biol. 1992 Mar;18(5):921-30. doi: 10.1007/BF00019206.
The T-6b gene of Agrobacterium tumefaciens strain Tm4 induces tumours on Nicotiana rustica by an as yet unknown mechanism. These tumours cannot be regenerated into normal plants. To study the effect of the T-6b gene product on normal plant cells, the T-6b gene was placed under control of the Drosophila melanogaster hsp70 heat-shock promoter and introduced into N. rustica. Progeny of an hsp70-T-6b transformant developed into normal plants. The inducibility of the hsp70-T-6b construct was shown by northern analysis and by heat-shock-dependent growth alterations on the level of whole seedlings. Upon wounding at normal temperature conditions hsp70-T-6b plants formed small tumours on leaves and stems. Grafts between transformed plants and normal plants led to a wound callus which remained limited to transformed tissues, indicating that the T-6b gene product does not diffuse. Protoplasts of hsp70-T-6b plants divided in the same way as control protoplasts under standard culture conditions. However, when protoplast cultures were started in the absence of hormones, normal cells rapidly lost their sensitivity towards hormones, whereas hsp70-T-6b cells remained sensitive for a significantly longer period. Thus, the T-6b gene product alters hormone sensitivity during the initial phases of protoplast culture.
根癌农杆菌菌株Tm4的T - 6b基因通过一种尚不清楚的机制在黄花烟草上诱导肿瘤形成。这些肿瘤无法再生为正常植株。为了研究T - 6b基因产物对正常植物细胞的影响，将T - 6b基因置于果蝇热休克蛋白70（hsp70）热休克启动子的控制之下，并导入黄花烟草。一个hsp70 - T - 6b转化体的后代发育成了正常植株。通过Northern分析以及在整株幼苗水平上热休克依赖性的生长变化，证实了hsp70 - T - 6b构建体的可诱导性。在常温条件下受伤时，hsp70 - T - 6b植株在叶片和茎上形成小肿瘤。转化植株与正常植株之间的嫁接导致伤口愈伤组织，且该愈伤组织局限于转化组织，这表明T - 6b基因产物不会扩散。在标准培养条件下，hsp70 - T - 6b植株的原生质体与对照原生质体的分裂方式相同。然而，当在无激素的情况下开始原生质体培养时，正常细胞迅速失去对激素的敏感性，而hsp70 - T - 6b细胞在显著更长的时间内仍保持敏感。因此，T - 6b基因产物在原生质体培养的初始阶段改变了激素敏感性。
