Butt A, Mousley C, Morris K, Beynon J, Can C, Holub E, Greenberg J T, Buchanan-Wollaston V
Plant Molecular Biology Laboratory, Wye College, University of London, UK.
Plant J. 1998 Oct;16(2):209-21. doi: 10.1046/j.1365-313x.1998.00286.x.
The metallothionein gene, LSC54, shows increased expression during leaf senescence in Brassica napus and Arabidopsis thaliana. A number of abiotic and biotic stresses have been shown to induce senescence-like symptoms in plants and, to investigate this further, the promoter of the LSC54 gene was cloned and fused to the GUS gene and transformed into Arabidopsis. The promoter was highly induced during leaf senescence and also in response to wounding; histochemical analysis indicated that this induction was localised to a few cells close to the wound site. The transgenic Arabidopsis tissue was infected with compatible and incompatible isolates of both the fungal biotroph, Peronospora parasitica and the bacterial necrotroph, Pseudomonas syringae. Incompatible isolates induced rapid cell death (the hypersensitive response) at the site of infection and, with both pathogens, early, localised expression of the GUS gene was observed. In contrast, relatively slow induction of the GUS gene was seen in the compatible interaction and this was correlated with the appearance of senescence-like symptoms in the biotrophic interaction and cell death by necrosis that occurred in response to the necrotrophic pathogen. These results suggest that there are common steps in the signalling pathways that lead to cell death in the hypersensitive response, pathogen induced necrosis and senescence.
金属硫蛋白基因LSC54在甘蓝型油菜和拟南芥叶片衰老过程中表达增加。许多非生物和生物胁迫已被证明会在植物中诱导类似衰老的症状，为进一步研究此现象，克隆了LSC54基因的启动子并将其与GUS基因融合，然后转化到拟南芥中。该启动子在叶片衰老期间以及对伤口的反应中均被高度诱导；组织化学分析表明，这种诱导作用局限于伤口部位附近的少数细胞。用真菌活体营养型寄生霜霉和细菌坏死营养型丁香假单胞菌的亲和性和非亲和性分离株感染转基因拟南芥组织。非亲和性分离株在感染部位诱导快速细胞死亡（过敏反应），并且对于这两种病原体，均观察到GUS基因早期的局部表达。相比之下，在亲和性互作中观察到GUS基因诱导相对缓慢，这与活体营养型互作中类似衰老症状的出现以及对坏死营养型病原体反应时发生的坏死性细胞死亡相关。这些结果表明，在过敏反应、病原体诱导的坏死和衰老过程中导致细胞死亡的信号通路存在共同步骤。
