Molecular genetic analysis of plant survival strategy by cell death

细胞程序性死亡是一种典型的现象，在许多生物体中早已为人所知。虽然我们对植物细胞死亡的机制细节知之甚少，但植物和动物之间的分子机制的某些方面是保守的。本研究旨在探索利用细胞死亡机制与应激生物学相关的基本策略。对细胞死亡相关基因的鉴定及其在植物抗逆性分子育种中的应用具有重要的研究意义。在这种情况下，一些调控细胞死亡的新基因引起了人们的兴趣。事实上，这些基因还能防止真菌侵袭和氧化应激。下面的例子是另一个很好的例子。过表达的水稻NADPH还原酶株系表现出对稻瘟病以及紫外线辐射、盐和淹水等多种非生物胁迫的抗性增强。这显然表明该基因在生物和非生物胁迫下通过新的途径参与植物的防御系统。大量证据表明，在生物和非生物胁迫下，H_2O_2作为一种重要的细胞介质，调节细胞的生长发育和触发细胞防御系统。在这项研究中，我们首次证明了NADPH还原酶对NADPH和NADP的氧化还原状态有反应，从而刺激整个植物的抗逆性。最后，我们提出了细胞死亡调控因子可用于抗逆性作物分子育种新工具的应用证据，这将为可持续农业提供便利。

Programmed cell death is a typical phenomenon, which has been known long time in many organisms. Although relatively little is known about the mechanistic details of cell death in plants, some aspects of the molecular machinery are conserved between plants and animals. This study was intended to find out the basic strategy to use cell death mechanism in relation to stress biology. Special interest has been paid in terms of identifying genes responsible for cell death, and application of such genes in molecular breeding of plants for stress resistance. In this context, some new genes, which regulated cell death, are intriguing. In facts, such genes also work to prevent fungus infestation as well as oxidative stress. Another good instance can be seen in the following example. The phenotype of over-expressed NADPH reductase lines of rice showed enhanced resistance to rice blast disease as well as various abiotic stresses, such as UV radiation, salt and submergence. This apparently indicates that such gene plays a role in plant defense systems via a new pathway under biotic and abiotic stress.A great deal of evidence has shown that H_2O_2 functions as an important cellular mediator regulating cell growth, development and triggering cell defense systems in both biotic and abiotic stresses. In this study, we demonstrated for the first time that NADPH reductase is responsive for redox state of NADPH and NADP, which in turn stimulate stress resistance as a whole plants. In conclusion we presented the evidence that cell death regulators can be used for the application of new tools of molecular breeding of stress resistant crops, which would be readily available for the sustainable agriculture.