The role of hydrogen peroxide as signalling molecule in leaf senescence and its impact on senescence-induced nitrogen mobilisation

尽管衰老的重要性，我们对这一过程的调节机制的知识仍然是零碎的。对于模式植物拟南芥，我们之前已经证明，在叶片衰老开始时，叶片细胞中的过氧化氢浓度通过过氧化氢清除酶的复杂调节相互作用而增加。过氧化氢峰与衰老的发生有关，很可能是通过重要的衰老相关转录因子如WRKY53或NAC92的转录上调。在油菜中，过氧化氢在发育性衰老过程中也被上调。在这种方法中，我们将更详细地分析过氧化氢在作物植物油菜中参与氮化合物动员的基因表达中的作用。在这里，我们将重点关注种子储存蛋白基因的表达，这些基因在过氧化氢谱后意外地在叶片中表达，并可能作为假定的临时N储存。这一现象只在油菜中发现，而在拟南芥中没有发现。此外，我们有几条证据表明，过氧化氢形成的细胞隔室对其信号功能很重要。因此，我们想继续建立过氧化氢的体内成像系统，使用过氧化氢敏感的绿色荧光蛋白直接针对拟南芥和油菜的不同细胞区室，以更准确地了解其调节作用，并从长远来看，创造出可以在衰老调节和氮动员中非常具体地操纵的植物。关键词：过氧化氢作为信号分子，过氧化氢清除酶（过氧化氢酶和抗坏血酸过氧化物酶），过氧化氢在sag基因表达中的作用，体内过氧化氢成像系统

Despite the importance of senescence, our knowledge on the regulatory mechanisms of this process is still fragmentary. For the model plant Arabidopsis thaliana we have previously shown that during the onset of leaf senescence the hydrogen peroxide concentration in the leaf cells increases by a complex regulatory interplay of the hydrogen peroxide scavenging enzymes. This hydrogen peroxide peak is involved in the onset of senescence most likely by transcriptional up-regulation of important senescence-associated transcription factors like WRKY53 or NAC92. In oilseed rape, hydrogen peroxide is also up-regulated during developmental senescence. In this approach, we will analyze the role of hydrogen peroxide in the expression of genes involved in the mobilization of nitrogenous compounds in more detail in the crop plant oilseed rape. Here, we will focus on the expression of seed storage protein genes which were unexpectedly expressed in leaves following the hydrogen peroxide profiles and possibly serving as a putative interim N storage. This was detected only in oilseed rape but not in Arabidopsis. In addition, we have several lines of evidence that the cellular compartment where the hydrogen peroxide is formed is important for its signalling function. Therefore, we would like to proceed with the establishment of an in vivo imaging system for hydrogen peroxide using a hydrogen peroxide sensitive GFP directed to different cellular compartments in Arabidopsis and oilseed rape to understand its regulatory role more precisely and in the long run create plants which can be very specifically manipulated in senescence regulation and nitrogen mobilization.Keywords: Hydrogen peroxide as signalling molecule, hydrogen peroxide scavenging enzymes (catalase and ascorbate peroxidase), role of hydrogen peroxide in gene expression of SAGs, in vivo hydrogen peroxide imaging system.