Vitale Luca, Vitale Ermenegilda, Bianchi Anna Rita, De Maio Anna, Arena Carmen
Institute for Agricultural and Forestry Systems in the Mediterranean (ISAFoM), National Research Council of Italy (CNR), P. le Enrico Fermi 1, Loc. Porto del Granatello, 80055 Portici, Italy.
Department of Biology, University of Naples Federico II, Via Cinthia, 80126 Naples, Italy.
Plants (Basel). 2022 Jul 18;11(14):1870. doi: 10.3390/plants11141870.
Plants are able to acclimate to environmental constraints through functional modifications that may also occur in tissues that are not directly exposed to stress. This process is termed "systemic acquired acclimation." The present study aims to evaluate the involvement of PolyADP-ribose) polymerase (PARP) protein in the acclimation process to high light (HL) stress in plants. For this purpose, some leaves located at the top of the plant, in the apical position, were directly exposed to HL ("inducing" leaves), while others on the same plant, distal from the top, continued to be exposed to growth light ("receiving" leaves) to verify the hypothesis that an "alert" message may be transferred from injured tissues to distal ones. Biochemical and eco-physiological analyses, namely PARP activity, HO and water- and fat-soluble antioxidants (i.e., ascorbic acid, tocopherol, glutathione (GSH), phenols, carotenoids, etc.) content, and chlorophyll fluorescence measurements were performed on both "inducing" and "receiving" leaves. Even if no change in PARP expression was found, its activity increased in "receiving" unstressed leaves in response to the light stress duration experimented by "inducing" leaves, while antioxidant capacity declined. When the "receiving" leaves were exposed to HL, the PARP activity returned to the control value, while antioxidant capacity photosynthetic electron transport rate (J) decreased and increased, respectively, compared to Control. Our results seem to show an acclimation pathway triggered in remote tissues not yet subjected to stress, likely involving a reactive oxygen species wave activating the PARP enzyme in a mechanism still to be clarified. In addition, the increased tolerance of plants directly exposed to HL could implicate a boosted synthesis of soluble antioxidants accompanied by a reduction of PARP activity to reduce excessive consumption of NAD(P).
植物能够通过功能修饰来适应环境限制，这些修饰也可能发生在未直接受到胁迫的组织中。这个过程被称为“系统获得性适应”。本研究旨在评估聚（ADP - 核糖）聚合酶（PARP）蛋白在植物对高光（HL）胁迫的适应过程中的作用。为此，将位于植物顶部顶端位置的一些叶片直接暴露于高光下（“诱导”叶片），而同一植物上远离顶部的其他叶片继续暴露于生长光下（“接受”叶片），以验证“警报”信息可能从受损组织传递到远端组织的假设。对“诱导”和“接受”叶片都进行了生化和生态生理分析，即PARP活性、过氧化氢酶（HO）以及水溶性和脂溶性抗氧化剂（如抗坏血酸、生育酚、谷胱甘肽（GSH）、酚类、类胡萝卜素等）含量的测定，以及叶绿素荧光测量。即使未发现PARP表达有变化，但其活性在“接受”的未受胁迫叶片中因“诱导”叶片所经历的光胁迫持续时间而增加，而抗氧化能力下降。当“接受”叶片暴露于高光下时，PARP活性恢复到对照值，而抗氧化能力和光合电子传递速率（J）分别与对照相比降低和升高。我们的结果似乎表明在尚未受到胁迫的远端组织中触发了一种适应途径，可能涉及活性氧波以一种尚待阐明的机制激活PARP酶。此外，直接暴露于高光下的植物耐受性增加可能意味着可溶性抗氧化剂的合成增加，同时PARP活性降低以减少NAD(P)的过度消耗。
