Hernández Iker, Munné-Bosch Sergi
Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, E-08028 Barcelona, Spain.
Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 643, E-08028 Barcelona, Spain
J Exp Bot. 2015 May;66(10):2889-900. doi: 10.1093/jxb/erv056. Epub 2015 Mar 4.
Plants have evolved a plethora of mechanisms to circumvent the potential damaging effects of living under low phosphorus availability in the soil. These mechanisms include different levels of organization, from root-shoot signalling at the whole-plant level to specific biochemical responses at the subcellular level, such as reductions in photosynthesis and the consequent activation of photo- and antioxidant mechanisms in chloroplasts. Some recent studies clearly indicate that severe phosphorus deficiency can lead to alterations in the photosynthetic apparatus, including reductions in CO2 assimilation rates, a down-regulation of photosynthesis-related genes and photoinhibition at the photosystem II level, thus causing potential photo-oxidative stress. Photo-oxidative stress is characterized by an increased production of reactive oxygen species in chloroplasts, which at low concentrations can serve a signalling, protective role, but when present at high concentrations can cause damage to lipids, proteins and nucleic acids, thus leading to irreversible injuries. We discuss here the mechanisms that phosphate-starved plants have evolved to withstand photo-oxidative stress, including changes at the subcellular level (e.g. activation of photo- and antioxidant protection mechanisms in chloroplasts), cellular and tissular levels (e.g. activation of photorespiration and anthocyanin accumulation) and whole-plant level (alterations in source-sink relationships modulated by hormones). Of particular importance is the current evidence demonstrating that phosphate-starved plants activate simultaneous responses at multiple levels, from transcriptional changes to root-shoot signalling, to prevent oxidative damage. In this review, we summarize current knowledge about the occurrence of photo-oxidative stress in phosphate-starved plants and highlight the mechanisms these plants have evolved to prevent oxidative damage under phosphorus limitation at the subcellular, cellular and whole-plant levels.
植物已经进化出大量机制来规避在土壤磷有效性低的环境下生存可能产生的有害影响。这些机制包括不同层次的组织，从全株水平的根-茎信号传导到亚细胞水平的特定生化反应，如光合作用的降低以及随之而来的叶绿体中光和抗氧化机制的激活。最近的一些研究清楚地表明，严重的磷缺乏会导致光合机构的改变，包括二氧化碳同化率的降低、光合作用相关基因的下调以及光系统II水平的光抑制，从而导致潜在的光氧化应激。光氧化应激的特征是叶绿体中活性氧的产生增加，低浓度时活性氧可起到信号传导和保护作用，但高浓度时会对脂质、蛋白质和核酸造成损害，从而导致不可逆转的损伤。我们在此讨论缺磷植物进化出的抵御光氧化应激的机制，包括亚细胞水平的变化（如叶绿体中光和抗氧化保护机制的激活）、细胞和组织水平的变化（如光呼吸的激活和花青素的积累）以及全株水平的变化（由激素调节的源-库关系的改变）。特别重要的是，目前有证据表明缺磷植物会激活从转录变化到根-茎信号传导的多个水平的同步反应，以防止氧化损伤。在这篇综述中，我们总结了关于缺磷植物中光氧化应激发生的现有知识，并强调了这些植物在磷限制下在亚细胞、细胞和全株水平进化出的防止氧化损伤的机制。
