Vidović M, Morina F, Milić-Komić S, Vuleta A, Zechmann B, Prokić Lj, Veljović Jovanović S
Institute for Multidisciplinary Research (IMSI), University of Belgrade, Belgrade, Serbia.
Institute for Biological Research 'Siniša Stanković', University of Belgrade, Belgrade, Serbia.
Plant Biol (Stuttg). 2016 Jul;18(4):669-80. doi: 10.1111/plb.12429. Epub 2016 Feb 3.
Hydrogen peroxide is an important signalling molecule, involved in regulation of numerous metabolic processes in plants. The most important sources of H2 O2 in photosynthetically active cells are chloroplasts and peroxisomes. Here we employed variegated Pelargonium zonale to characterise and compare enzymatic and non-enzymatic components of the antioxidative system in autotrophic and heterotrophic leaf tissues at (sub)cellular level under optimal growth conditions. The results revealed that both leaf tissues had specific strategies to regulate H2 O2 levels. In photosynthetic cells, the redox regulatory system was based on ascorbate, and on the activities of thylakoid-bound ascorbate peroxidase (tAPX) and catalase. In this leaf tissue, ascorbate was predominantly localised in the nucleus, peroxisomes, plastids and mitochondria. On the other hand, non-photosynthetic cells contained higher glutathione content, mostly located in mitochondria. The enzymatic antioxidative system in non-photosynthetic cells relied on the ascorbate-glutathione cycle and both Mn and Cu/Zn superoxide dismutase. Interestingly, higher content of ascorbate and glutathione, and higher activities of APX in the cytosol of non-photosynthetic leaf cells compared to the photosynthetic ones, suggest the importance of this compartment in H2 O2 regulation. Together, these results imply different regulation of processes linked with H2 O2 signalling at subcellular level. Thus, we propose green-white variegated leaves as an excellent system for examination of redox signal transduction and redox communication between two cell types, autotrophic and heterotrophic, within the same organ.
过氧化氢是一种重要的信号分子，参与植物众多代谢过程的调控。光合活性细胞中H2O2的最重要来源是叶绿体和过氧化物酶体。在这里，我们利用斑叶天竺葵在最佳生长条件下，在（亚）细胞水平上表征和比较自养和异养叶片组织中抗氧化系统的酶促和非酶促成分。结果表明，两种叶片组织都有调节H2O2水平的特定策略。在光合细胞中，氧化还原调节系统基于抗坏血酸以及类囊体结合抗坏血酸过氧化物酶（tAPX）和过氧化氢酶的活性。在这种叶片组织中，抗坏血酸主要定位于细胞核、过氧化物酶体、质体和线粒体。另一方面，非光合细胞含有较高的谷胱甘肽含量，主要位于线粒体中。非光合细胞中的酶促抗氧化系统依赖于抗坏血酸-谷胱甘肽循环以及锰和铜/锌超氧化物歧化酶。有趣的是，与光合叶细胞相比，非光合叶细胞胞质溶胶中抗坏血酸和谷胱甘肽含量更高，APX活性更高，这表明该区室在H2O2调节中的重要性。总之，这些结果意味着在亚细胞水平上与H2O2信号传导相关的过程存在不同的调节。因此，我们提出绿白相间的斑叶作为一个优秀的系统，用于研究同一器官内自养和异养两种细胞类型之间的氧化还原信号转导和氧化还原通讯。
