Vitale Luca, Vitale Ermenegilda, Costanzo Giulia, De Maio Anna, Arena Carmen
National Research Council (CNR), Department of Biology, Agriculture and Food Science (DiSBA), Institute for Agricultural and Forestry Systems in the Mediterranean (ISAFoM), P.le E. Fermi 1-Loc. Porto del Granatello, 80055 Portici (Na), Italy.
Department of Biology, University of Naples Federico II, Via Cinthia, 80126 Naples, Italy.
Plants (Basel). 2020 Sep 12;9(9):1192. doi: 10.3390/plants9091192.
The Crassulacean acid metabolism (CAM) pathway helps plants to alleviate the oxidative stress under drought, but the shift to CAM-idling may expose plants to the overproduction of reactive oxygen species causing cell damages. The facultative CAM species L., was subjected to long-term water deprivation to assess the photo-protective strategies and the poly (ADP-ribose) polymerase (PARP) activity during water stress and plant capability to recover from the stress. Measurements of titratable acidity, chlorophyll fluorescence emission, and antioxidant activity were performed during the stress and rewatering. Under water deprivation, plants shifted from C3 to CAM metabolism, reaching the CAM-idling status at the end of the stress period. The daily variation of the titratable acidity and PARP activity increased at the beginning of stress and declined with stress progression, reaching the lowest value at the end of stress treatment. HO content, superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities increased with the severity of water stress. The photochemical processes remained high during the entire stress period indicating the presence of alternative sinks to CO fixation. The elevated activity of catalase under severe water stress suggests the occurrence of photorespiration in sustaining the photosynthetic electron transport under CAM-idling condition. The overall data indicate that scavenger enzymes, photorespiration and PARP activity modulation contribute to the strong resistance of to severe water stress, preserving the functioning of photosynthetic apparatus and ensuring plant recovery with rewatering.
景天酸代谢（CAM）途径有助于植物缓解干旱胁迫下的氧化应激，但转变为CAM待机状态可能会使植物暴露于活性氧过量产生的环境中，从而导致细胞损伤。对兼性CAM植物L.进行长期缺水处理，以评估其在水分胁迫期间的光保护策略和聚（ADP-核糖）聚合酶（PARP）活性，以及植物从胁迫中恢复的能力。在胁迫和复水过程中，对可滴定酸度、叶绿素荧光发射和抗氧化活性进行了测量。在缺水条件下，植物从C3代谢转变为CAM代谢，在胁迫期结束时达到CAM待机状态。可滴定酸度和PARP活性的日变化在胁迫开始时增加，随着胁迫的进展而下降，在胁迫处理结束时达到最低值。HO含量、超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性随着水分胁迫的加剧而增加。在整个胁迫期间，光化学过程保持较高水平，表明存在替代CO固定的途径。严重水分胁迫下过氧化氢酶活性的升高表明，在CAM待机条件下，光呼吸在维持光合电子传递中发挥了作用。总体数据表明，清除酶、光呼吸和PARP活性调节有助于L.对严重水分胁迫的强大抗性，保持光合机构的功能，并确保植物在复水后恢复。
