Molecular genetic analysis of programmed cell death

细胞程序性死亡（PCD）是一个生理过程，是所有生物生命的一部分。在植物和动物中，PCD对于正常发育和清除受损或感染细胞至关重要。不同类型的PCD在植物细胞中被描述为对发育线索、病原体感染或非生物胁迫的反应。PCD的一个例子可能发生在病原体进入部位的受感染叶片上（所谓的“超敏反应”），以限制病原体的传播。这种反应通常与植物中特定抗病机制的诱导有关。在本研究项目中，参与细胞死亡和细胞存活途径激活和调控的早期事件和蛋白质将在植物模型拟南芥中进行表征。一种独特的遗传方法将被用来确定控制紫外线- c照射诱导的PCD的关键调节因子。这一信息将有助于了解在某些类型的植物防御反应中如何有利于细胞存活，然后可以应用于无症状抗性植物的开发。第二种方法是研究一种植物毒素诱导pcd的活性，这种植物毒素是马铃薯常见结痂病发生所必需的。我们已经证明，TA通过抑制拟南芥细胞悬浮液中的纤维素生物合成来激活PCD。我们将研究TA在整个植物中的作用，并描述激活这一细胞死亡过程的早期信号。此外，我们已经生产出植物细胞悬浮液，可以在致命浓度的TA存在下生长。将分析这些细胞中基因表达的变化，以确定这些细胞如何存活到TA。我们认为这一数据将导致植物对干扰植物细胞壁的胁迫，如TA，伤害和病原体感染的耐受性更强。

Programmed cell death (PCD) is a physiological process that is part of the life of all organisms. In plants and animals, PCD is essential for normal development and for the removal of damaged or infected cells. Different types of PCD have been described in plant cells in response to developmental cues, pathogen infection or abiotic stresses. One example of PCD may occur on infected leaves at the site of pathogen entry (the so-called "hypersensitive response") to limit pathogen spread. This response is generally associated with the induction of a specific disease resistance mechanism in the plants.         In this research program, the early events and proteins involved in the activation and regulation of cell death and cell survival pathways will be characterized in the plant model Arabidopsis thaliana. A unique genetic approach will be used to identify key regulators in the control of PCD induced by UV-C irradiation. This information will be useful to understand how cell survival may be favoured in some types of plant defence reactions and could then be applied to the development of symptom-less resistant plants.     A second approach studies the PCD-inducing activity of a phytotoxin, thaxtomin A (TA), that is essential for the development of common scab disease of potato. We have shown that TA activates PCD through inhibition of cellulose biosynthesis in Arabidopsis cell suspensions. We will examine the effect of TA in whole plants and characterize the early signals that activate this process of cell death. Moreover, we have produced plant cell suspensions that can grow in the presence of lethal concentrations of TA. Changes in gene expression in these cells will be analysed to determine how these cells can survive to TA. We think this data will lead to the development of plants that are more tolerant to stresses perturbing the plant cell wall, such as TA, wounding and pathogen infection.