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

尽管衰老很重要，但我们对这一过程的调控机制的了解仍然很零碎。对于模式植物拟南芥，我们先前已经证明，在叶片衰老开始期间，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控相互作用而增加。这个过氧化氢峰与衰老的开始有关，很可能是通过转录上调重要的衰老相关转录因子，如WRKY53或NAC92。在油菜中，过氧化氢在发育衰老过程中也受到上调。在这种方法中，我们将更详细地分析过氧化氢在作物油菜中参与氮化合物动员的基因表达中的作用。在这里，我们将集中于种子贮藏蛋白基因的表达，这些基因在叶片中意外表达，遵循过氧化氢的特征，可能是一种可能的临时N贮藏。这只在油菜中检测到，而在拟南芥中没有检测到。此外，我们有几条证据表明，过氧化氢形成的细胞室对其信号功能非常重要。因此，我们希望利用针对拟南芥和油菜不同细胞室的过氧化氢敏感的绿色荧光蛋白建立过氧化氢的体内成像系统，以更准确地了解其调节作用，并从长远来看，创造可以非常特异地调控衰老和氮素动员的植物。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SAGs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.